lPORLtULA, DOUGH MIXING METHODS, AND KEEPING Q,UALITIES OF A SWEET YEAST RO.LL MIX

b7 BARBARA ANN ROBINS

.A. THESIS submitted to OREGON STATE OOI.I.JnE

tn partial tultillment or tbe requirements tor the degree or MASTER OF SCIENCE June 1954 qfri lrilrlr| if ,'|t&

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rtiltil{fT The writer wishes to express her sincere apprecia­ tion to Dr~ Andrea 14acUcey tor the stimulating way in which she directed this study and tor the t~e and ettort given, beyond the call ot duty, in preparation ot this manuscript. Appreciation is expressed to the author's husband, Charles s. Bobins, tor the interest and oontidence he has shown in her work and tor the many ways in which he made 1t possible. Acknowledgment is gratefully made to Belen Charley, Grace Goertz. Alta Garrison, 14er1anne Strauss and Emogene Veal tor their assistance in evaluating the products. TABLE OJ' CONTENTS

CHAPTER Page

I IBTRODUCTION • • • • • • • • • • • • • • • 1

II REVIEW OP Ll'l'EBJ.TURE • • • • • • • • • • • 5 Yeast • • • • • • • • • • • • • • • • • 5 Controlling Dough DeTelopaent • • • • • ll By'drogen-Ion Oonoentration. • • • • • • 21 Colloidal Properties ot Doughs. • • • • 24

III EIPERDIENTAL PROCEDURE • " . • • • • • • • Zl Introduotion. • • • • • • • • • • • • • 31 Ingredients • • • • • • • • • • • • • • 34 :rorm.ulas. • • • • • • • • • • • • • • • 35 Mixing Methods. • • • • • • • • • • • • 36 Handling Kethods Atter Mixing • • • • • 38 Equipment tor Preparing Rolls • • • • • 40 Equipaent tor Measurements. • • • • • • 40 Measurements to Determine Mix Properties • • • • • • • • • • • • • 41 Measurements to Determine Dough Properties • .. • • • • • • • • • • • 42 Measurements to Determine Roll Properties • • • • • • • • • • • • • 45

IV RESULTS AND DISCUSSION • • • • • • • • • • Properties ot the Mixes • • • • • • • • 47 Doughs. • • • • • • • • • • • • • • • • 57 Bolla • • • • • • • • • • • • • • • • • 66

v • • • • • • • '/7

BIBLIOGRAPHY. • • • • • • • • • • • • • • • • • • • • eo APPENDIX ••• • • • • • • • • • • • • • • • • • • • • 84 LIST or TABLES

TABLE Page 1 Methods tor Mixing Doughs • • • • • • • • • 37 2 Meaaureaents ot Mixogram Patterns in Units ot 1/~0 InOh •••••• . • • • • 49

(Appendix) I ATerage Carbon Dioxide Production, pH Values and Ratio ot Active to InactiTe Yeast Cells tor Each Mix at o, 5, and 10 eeka Storage • • • • • • • • • • • • 85

II ATerage Proofing T~ea 8Dd Fermentation Timea tor Doughs at O, 5, and 10 eeka Storage. • • • • • • • • • • • • • • • • 86 III Ezpanaib1lit7 of Doughs as Indicated by Volume Attained and Ttme Required tor Maxlmum Expansion. • • • • • • • • • • • 87 IV Average pH Values at iach Storage Period ot Standard and Mix Dougha When Firat Prepared, After lermentation, and After Proot1na • • • • • • • • • • • • • 88 v Analysis ot Variance ot Scores tor Roll Palatability •••••••••••• • • 89 VI ATer ge Soores tor Rolle ade From Rolls Made by Three Methods From Freshly Prepared Mix • • • • • • • • • • • • • • 90 VII ATerage Soores tor Rolls Jlade by- Three Methods Jrom Mixes Stored 5 eeka. • • • 91 VIII Average Scores tor Rolla Made by Three Methods From ixes Stored 10 eeks • • • 92 IX Analya1s ot Variance ot Roll Cross­ Section Areas. • • • • • • •••• • • • 93 X ATerage Cross-Section Areas ot Standard Rolls and Rolls Made by Three Methods From Mixes Stored 0, 5, and 10 Weeks •• LIST OJ' J'IGURES liGURE Page

1 Looat1on ot M1::mgr8lll Meaaurements • • • • • 48 2 Relationship ot Aot1ve-InaotiYe Yeast Oella to Extent ot Break in Mi::mgrem Patterns During Storage. • • • • • • • • 55 Relationship ot the Total Oarbon Dioxide Production to the Total J'er.mentation Time ot Eaoh Mix • • • • • • • • • • • • 55 Relationship or Total Carbon Dioxide Production to Dough Expansion at Eaoh Storage Period • • • • • • • • • • • • • &l Relationship During St.orage ot Dough Expansion to Kixogrea Measurements; . Height to Peak and Length to Peak. • • • 61 6 Relationship of Roll Cross-section Area to Mixogram Extent of Break tor Mix II at Eaoh Storage Period. • • • • • • • • • • 63 7 Relationship of Dough Expansion to Total ~ermentation Ttme at Eaoh Storage Period 63 e Relationship ot Final Dough pH to Dough Expansion tor Eaoh Mix • • • • • • • • • 65 9 Relationahip ot J'inal Dough pH to Total J'ermentat1on T~e at Eaoh Storage Period 65 10 Relationabip ot Cross-Seotion Area to Dough Expansion tor Eaoh Klx • • • • • • 11 Belat1onah1p ot Cross•Seotion Area to Total J'ermentat1on Ttme ot Bolls Prepared by lour Mixing Methods :rrom Jlixes I end II . • • . • • • • • • . • • • 12 Relationship ot Total Crumb Springiness Soorea to Total Fermentation Time of Rolla Prepared by Four Dough Mixing Methods. • • • • • • • • • • • • • • • • 71 LIST OF J'IGURBS (Coo.t.)

J'IGURB Page 13 Belat.ionshlp ot Total Crumb Oolor Sool"•• to Total Fermentation Time Gt Rolls PJ.'epared by Four Mixing Methods From. 141xe.s I end II • • • • • • • • • • • .. . 71 14 Relationship or Total Odor Scores to 'rotal F rm.e.u ...e.tion Time of Rolla Prepared 'by re't.Ul' Kixlng Methods. • • • • '14 15 Relationship ot Total 7la•or Scores to Total J'erm.entati~ul Time ot Bolle Prepared by Four Mi•lns Methods From Mixes I and III. • • .. • • , • • • • • • 11 Belat1oneh1p ot Total Odor and Flavor soores to Final ;Dough pH at Baoh Storage Period • • .. .. • .. " , • • • • • 75

(Appendix) I Bttect ot Ditterent Yeasts on t.ftxosram. Patterns • • • • • • • • • • • • • • 95 I ,I . Etteot ot Freshly Prepared Mixes on Mtxogram ~att•rna. • • • ~ • • • • • • • 96 III Etteot ot Kixes on JUxogrem. Patterns After 10 Weeks ot Stol'"age. • • • • • • • 97 · IV External end Internal Appearance ot Standard and Mix Rolls Alter 10 Weeks Storage. • • • • • • • • • • • • • • • • 98 FORMULA, DOUGH MIXING METHODS , AND KEEPING UALITIES OF A SWEET YEAST ROLL MIX

CHAPTER I

INTRODUCTION

A "mix" may be defined (16. p.l075) as an assemblage ot substances that are thoroughly diffused among one an­ other. The word "mix" when a pplied to a food product 1m­ plies an intimate blend ot ingredients or tood materials.

The current popularity of tood ready..:mixes may be attributed largely to the convenience associated with their use. M8DY . Of the ingredients necessary tor prepar­ ing the desired tood product have been assembled, measured and combined in advance. Thus, the steps involved at the time of rood preparation e.re reduced in number. The chief' object of the present investigation was to develop a yeast ready-mix formula which the homemaker could prepare and store at home. and use as a convenient shortcut for the preparation of a variety of yeast­ leavened products. Previous to this investigation, no yeast ready-mix formula had been developed. The mix here­ in reported is the first to omit flour and include yeast as an essential ingredient. It retains the aspect ot con­ venience, at the same time eliminating several problems heretofore associated with the home preparation end stor­ ase ot mixes. 2 Ot the mixes whioh haTe been developed tor home prep­ aration, ell involTe the sitting together ot the dry in­ gredients which oonsiet ot tlour, baking powder, dried milk, salt and sugar. The shortening is then blended with these combined ingredients. A cumbersome aapeot in the preparation ot these mixes ia the handling ot large quan­ tities ot dry ingredients wh1oh must be aitted together several times. Another is blending the tat into auoh quantities of dry ingredients. A further problem 1a the storage ot the completed mix. Ita large bulk introduces the necessity of finding numerous suitable containers as well as shelt or refrigerator spaoe. In oontre.at to the problema inherent in the usual home-prepared mix, the yeast ready-mix tormula described in this paper 1a easy to prepare and store. The omission ot flour reduces the bulk, thus simplifying both the preparation and storage ot the mix. The formula includes shortening, sugar, aalt, powdered egg, powdered milk end active dry yeast. These ingredients are blended together to form e. oreamy, attractive mix or smell volume. Beoaus or their many adTante.ges, mixes have won a permanent plaoe in the baking industry. They make pos­ sible real savings in labor, storage space, and time. They reduce the possibility or error by limiting the num­ ber ot ingredients that must be soaled. They help to 3

insure the uniformity and high quality ot the finished product•. Laster {24, p.ll4) states that there have been sever­ al types ot yeast bread mixes available tor use in commer­ cial bakeries. The tirst ot these mixes was designed to produce a basic sweet-yeast dough trom which a variety ot goods were made. Certain disadvantages were tound to be associated with the basic dough. It was essentially a . compromise dough yielding several products ot acceptable quality. However, none ot these were ot optimum quality. Because ot this shortcoming ot baste doughs, mixes have been developed tor 1nd.1vidua.l yeast-leavened products suoh as doughnuts and cottee cake. By adding eggs or

tlour to these mixes opt~um doughs were obtained tor still other specific products. For example, eggs added to the oottee cake mix gave an optim.um dough tor Danish pas­ try. The baker, theretore. used several mixes plus tlour and eggs in order to obtain optimum quality doughs tor all ot his products. Although the mix reported herein was developed pri­ marily .tor home preparation and use, 1ts possible commer­ cial applications should. be considered• . The yeast ready-mix formula developed 1n this inves• tigation hes been compared with Frey's (18, p.2l) commer­ cial yeast dough formulas. The ingredients other than flour and water were tound to be Yery nearly identical in proportion to tho ae 1n the lean sweet-yeast dough formula. By the atmple expedient ot varying sugar, eggs, and water, this yeast ready~1x might be adapted to the production ot lean, medium and rioh sweet-yeast doughs. It might, there­ tore, be possible tor the baker to prepare top quality doughs tor all or his sweet-yeast products trom one mix. The mix reported herewith should haTe many uaetul applications tor both tbe homemaker and the commercial baker. Sinoe this type ot mix is new, both in ita prepara­ tion and use, m&n7 quest ions ha'fe arisen oonoerning 1:ta properties and action. In deTeloping the mix formula and investigating ita storage behavior, these basio questions were seleoted tor investigation: 1. Does the mix giYe rolls ot acceptable quality? 2. How does storage in tbe preaenoe ot oonoentrated ingredients atteot yeast activity? 3. How does tbe dough mixing method atteot the aotion ot the mix? 5 OBAPT'ER II

RIVUW or LITBJU.!URB

Yeast

Charaoter1at1ca of .lctiTe Dry Yeast

Active dry yeast was used in this atudy. It is appropriate, therefore, to oonsider ao:rae of ita properties. Active dry yeast is prepared by exposing finely di­ vided compressed yeast to war.m dry air (31, p.5). The mo,iature oontent is reduced to a per cent compared with 70 per cent in the tresh yeast. A dry,, triable, relatiftly stable, but still active yeast is obtained. Active dry yeast (1 1 p.302) ia composed ot 8 per cent moisture, 56 per oent protein, 3 per oent tat, 7 per oent ash, 26 per oent nitrogen-tree extract and 0.56 per oent ergosterol. lor eaoh ounce or active dry yeast used 1n a dough, the total water in the dough tor-mula must be inoreaaed by 3 to 4 ounces (28, p.27). Two ot these merely replace the water lost in drying while the remainder is required to obtain a dough ot ideal oonsiatenoy. The a.ctive dry yeast seems, therefore, to increase the water absorption capac­ ity ot the dough. Active dry yeast ditters 1n aotion trom fresh yeast in the tollow1ng ways (28, p.28): •or the tirst hour ot 6 dough te~entation, the quantity ot gas evolved is otten less 1f1 th aotive dry yeast than with fresh yeast. The ditterenoe no longer exists after the ~irat hour ot fer­ mentation. Dry yeast doughs ha~• more tolerance to fer­ mentation, and eXhibit a smooth, silky, malleable ohar­ aoteriatio wh1oh 1s not as pronounced with treah yeast doughs. A smoother break and ,ab.Hd may be e:xpeoted trom the doughs made with active dry yeast. Many workers have reported that yeasts o:n the retail market vary considerably in their gas~produoing ability. swanson and swanson (38, p.432) reported that the loat volumes seoured from the same unif'orm lot ot flour but with different lots ot yeast ranged trom 855 ml. to 980 ml. The variation was greatest in summer and early tall months, suggesting a loss ot viability, probably due to laok ot unito:nalty in the storage conditions atter manufacture.

J'aotors Atteottns Viability ot Aotive Dry Yeast

Among the, environmental taotors that may att•ot yeast viability are: humidity, temperature, sugar oonoentration, hydrogen-ion concentration, and available oxygen. Crane, Steele, end Derf'ern (lO, p.220). state that aotive dry yeast does not represent a state ot suspended animation. The yeast is resp1rtns slowly and anything that decreases tb.e rate ot respiration without injury to 7 the cella will haTe a taTorable influence on the keeping quality ot the actiTe dry ye at. Following a study of storage conditions as they attect viability or active dry yeast, tbey stated that the three most bnportant taotors influencing lite expectancy of yeast are moisture, oxygen, and temperature. They round (10, pp.220-221) that as the moisture content ot the yeast increased above a per cent, the stability ot tbe yeast decreased end tbe dough fermen­ tation speed markedly decreased. The oisture content ot the yeast varies with the relative humidity. It has been shown (10, p.221) that active dry yeast neither gains nor loses moisture at relative humidities ot 32 per cent at 80° F. or 45 per cent at 100° F. Therefore, tbe optimum storage humidity tor active\dry yeast depends Up()n the temperature. As the active dry yeast is slowly respiring (10, p.220) the lite expectancy is significantly improved by storage 1n a substantial absence ot oxrsen, wh1ob is re­ quired tor respiration. Oyaas, Johnson end Peterson (32, p.280) stored yeast 1n glass jars 1n nitrogen containing various percentages ot oxygen. When stored act1•• dry yeast was used, the time required tor adequate dough fer­ mentation increased as the percentage ot oxrgen in the storage atmosphere increased beyond 5 per cent. The e samples paokaged in air deteriorated slowly tor the tirst three months and then the rate or deterioration gradually inoreaaed. It has been shown (10, p.222) that temperatures ot 100° l. or above rapidly weaken aotive dry yeast. A' re­ frigerator temperatu~s the yealt, though slowly deterio­ rating, was still oapable ot mak1ng a good loat atter 7 months ot storage when slower fermentation rates were used. It was found (10, p.222) that the etteot ot temperature on tbe yeast is more a matter ot the maximum temperature attained than it is or the giTen aYerage temperature ot storage. That is, it the yeast is exposed tor a short period to a relatively high temperature • for example 100° F., and the temperature is then reduoed, the etteot on the performance or the yeast will be greater then 1t exposed to the average o"t these two temperatures over the same period ot time. The etteots ot sugar oonoentration and hydrogen-ion oonoentration on the longeTi~ ot aotiTe dry yeast have not been reported. HoweTer. observations on fresh aotive yeast haTe shown that beaTf sucrose syrup solutions (27, p.481) have a protective action with regard to the longeT­ ity or active yeast cells. Lindegren (25, p.51) states 'hat when a yeast cell is suspended in a medium oontaining an excess ot carbohydrate, glyoogen 1s deposited. The 9 aooumQlated reserves generally intertere with growth, t6r­ mentat1on and respiration. When the proper reserves aoou• mulate in sutticient variety, the cell becomes dor.mant.

However, a 10 per cent sugar solution (~5, p.51} causes m~ny ot the cells to autolr~e and only a tew attain full dormancy. Mol'arlene (27, p.482) studied the ettects of differ­ ent hydrogen-ion concentrations on the viability ot fresh active yeast stored at sub-freezing temperatures. At pB

6.5 1 in the more dilute sucrose oonoentrations (5 to 20 per oent) a high percentage (Si per oent) of the yeast cells were killed while in tbe more concentrated sucrose media (30 to 50 per oent) only halt as many yeast cells were killed. At a pH ot 6.5 more oells were deetroyed than at a pH ot 5.0 in all sugar concentrations. Tb.e most destructive tor all yeast oells were pH values ot 3.6 ­ 3.7. It has been reported (20, p .. 3) that tresb. or active dry yeast will deteriorate in time regardless of the stor­ age oondi tiona. Fwm the o bservs.tiona on eotive clry y:eaa-c no ted above, it may ~· concluded that humidity, temperature, oxygen and time will artect the v1a'bil1ty ot active dry yeast. From observations on tresh aotive yeast it may be assumed that 10 s~ar concentration in rel tion to p!l m·ey als-o influence the viability ot aotive dry yeast.

Ettects ·ot Non-Viable teast Cells

About 85 per cent ot th yeast cells survive the a.rr­ tng process (10, p.220) whioh -~s that perhaps 15 per oent ot the oells ere non-viable. This latter peroentase may increase during etoraee. The presence ot non-viable yeast cells baa many dele­ terious etteots both on the doUgh properties and on the viability or the remaining cells.

Davis end Frenkel (12 1 p.lOO) tound that oommero1al aotive dry yea·sts vary oons14erably 1n the degli'fte to which they attect the phYsical oharacteristios of the dough. The inclusion ot dead cells 1n a dough batch has a pro­ nounced dough softening etteot. The dough oondition 1m.... proves somewhat during ter.mentat1on, but the deleterious effect persists throughout the bread-makiug process and "sults in tnrerior bread. These changes (35, p.l49) are due ma1nl:r to alterat1on ot the sluten 1ndu.oed by ~he dead yeast. This reaction me.y be (12, p.l09) enZ1Jile.t1o in nature or may be due to reducing substances released trom the. oells when they ere rendered Ron-vi&bile.. In addition to their efteot on the dough, non-viable oella have intluenoe on tb.e viable o•lls. The autolysate 11 ot the 4ead oells (25, p.ll) encourages the tormat1on ot tat in 'the viable cells resulting in dormancy. However, the inclusion ot dead yeast in the dough has little ettect . on the gas production or the '1"1able cells (30, p.l23).

Controlling Dough DeveloPlllent

As the dough ter.ments, changes take place which are called "ripening." Carbon dioxide is produced which leav­ ens the dough end there is en increase in acid1ty. The gluten loses some of its elasticity and tenacity. It is believed (40, p. 382) that the change in gluten is due to a change in 1tes colloidal nature as a result ot proteolytic activity. In order to make good quality bread, dough .ripen1ng must be controlled. The rate or gas evolution must be controlled so tb.at it is optimum tor the dough properties. The rate ot enzyme activity must be controlled so that the dough will be properly extensible when the dough 1a leav­ ened and ready tor baking. Means tor oontroll1ng each ot these factors must be tound.

Controllinl Rate or Gas Evolution . ­

The rate at which gas is produced 1n a dough (21, p.229) is not constant but varies as fermentation proceeds. At first it increases and then decreases. It has been 12 shown (29, p.585) that the most important factor influenc­ ing loat volume is the gas eTOlved in the latter part of the pan-proof period. The maintenance ot adequate gaa production during this period results i.n high loat volume. It is important, therefore, to oontrol the rate ot gas evolution 1n order to obtain optimum loat volume. The rate of carbon dioxide production (14, p.23) is a function of the amount and kind ot auger present, selt concentration, yeast toods, amount of yeast, soluble nitro­ genous substances, and temperature. The two major factors which may be used to oontrol gas evolution ere, tberetore, dough tormula and t mperature. Here we are concerned only with the dough formula. The rate at which gas is produced (21• p.229) and the peak ot its production vary with the proportion ot yeast used end the presence ot yeast st~ulants. There are a number of compounds which, when added to the dough, will stimulate the yeast cells to more rapid activity. When 0.6 per cent yeast is used the peak in gas production occurs atter 8 hours. 1th 2 per cent yeast, tbB peak in gas evolution oomes during tbe fourth hour. When yeast stimulants are added, the time ot maximum gas production remains the same tor each per cent ot yeast, but the quan­ tity ot gas evolved 1s tremendously increased. When other conditions are the same, the rate of gas evolution may, 13

therefore, be controlled by varying the quantity or yeast and yeast stimulants present in the dough. The emount or salt end sugar in the dough may also attect the rate of gas production. The chief function or salt is to impart flavor to the finished loat or 'bread, bat ·it has other runotions in the dough. Walden and Larmour (43, ·p.34) tound that salt ex­ hibited an over-all depressing and extending etteot on the term.enliati-on by slowing up yeast aot1on. However. it also promoted the development ot a healthy ter.mente.tion (8, p.&9) by retarding the development ot bacterial action. In so doing it aided in the control ot excessive acidity trom this source. Salt has been reported (8 1 p.69) to stimulate enzymatic activity when used in normal amounts, helping in this way to provide a medium suitable tor yeast activity. Only it it is present in amounts larger than 2 1/2 per cent will it adversely attect yeast activity. Brown (8, p.69) stated that selt exerts a definite strengthening etteot on the gluten. The binding action on the gluten by salt enables it to bold water and gas more ef'teotively and to expend without breaking, thereby in­ creasing its gas retention. Kent-Jones and Price (22, p.51) neme tlour; yeast, salt and water as the essential ingredients in bread and make no mention ot sugar. Sugar is a constituent ot tlour 14

(40, pp.371-372) and during fermentation flour diastase hydrolyzes part ot the starch to sugar when conditions of moisture and temperature are favorable. The tlour may not have enough diastatic aotiYity, however, and either malt or sugar must be added to the dough. Sugar is usually included in the bread formula tor flavor and tor sttmulation ot early yeast growth (40, ·p.379). Increasing the amount of sugar in the formula

(43, p.30) augments the initial gassing rate and d~in­ ishes and delays the fermentation attributable to sugar produced by diastase. When a great amount of sugar is used (14, p.23) it lengthens the ttme ot fermentation. Other tunotiona ot sugar in dough are discussed by Lowe (26, p.4&6). Sugar peptizes flour proteins elevating their coagulation temperature. In incre sing amounts 1t delays attenuation ot the gluten and gelatinization ot the starch. Sugar tends to increase the volume and tenderness of the baked product. Por yeast raised products, there are several formulas commonly in use. Given the same conditions, the dough containing the larger proportions ot auger, shorteniDg, milk and eggs (18, p.21} will result in a more superior product than when lesser proportions ot these enriching ingredients are used. Such products have a more appealing 15 taste, better flavor, more desirable eating qualities, e.nd tend to preserve their freshness tor a longer ttme. They will generally ter.ment at a markedly slower rate than will the leaner doughs. However, the higher proportions of in­ gredients (e, p. 53) serve as stabilizers 1n fermentation and richer doughs will have higher fermentation tolerance. Lean doughs will ripen more readily than richer doughs, but •111 laok ter.mentat1on tolerance. controlltns Do\!@ RiEenins ,

Ripening ot the dough is brought about by the enzymes in the dough and yea.st. Let us consider the important enzymes and taotors affecting their s.ot1v1ty as related to control ot dough ripening. Enzlllles .in Doy.eh: The most important enzymes 1n dough are protease, diastase, invertase, malt se, and zymase. The proteaees, present in tlour and malt (14, p.23), tunotion to soften the gluten and render 1t extensible. They exert their muimum aotivity at 120° F. at a pH ot 5.0 (8, p.55). It protease activity is properlY control­ led a oonsistenoy ideally suitable tor expansion in the oven 1s obtained. However, 1t too much proteolysis takes plaoe in the dough (21, p.225), it will become too slack and tail to retain the gas satisfactorily. Proteolytic act1on 1s most rapid during proofing and baking end e·xcess 16 proteolysis most often becomes evident at this time. One seldom discovers a soft, sticky dough at the end of dough fermentation to warn or too much proteolysis. This oom­ plioates the problem of controlling dough r 1pening. Starch is rendered soluble and is oonverte4 into sugar by the enzyme. diastase, J>resent in flour and malt (14, p.23). Thaysen and Galloway (42, p.228) point out that more susar ia needed -by the yeast d.ur.ing fermentation than ia supplied by the to~ula, and diastase activity makes available the needed additional sugar. While bish diaatatio activity is paralleled by high proteolytic aotiv·i ty, the converse is not necessarily true (8, p.55). Diaste.tio activity is readily destroyed undfitr conditions that do not atteot proteolytic activity. Since proteolytic enzymes exert their maximum activitJ at about 120° F. and the diaatatio enzymes at a higher temperature • 140- 160° F., the temperatures or the dough are more te.Torable for proteolytic aot1Tity than dtastatio aot1v1ty throughout the greeter part ot the fermentation. Only 111 the oven are temperatures reached tor maximum activitY tor either enzyme and the t~e interval at which these temper­ atur•s are operative is small, yet important. These en­ zymes are more aottve during the pan-proof and the first tew minutes in the oven than during the previous stages of' the fermentation when the temperature ot the dough is 1'1 lower. BonYer, the lower do\JSh 'emperatures are within the range ot aot1Y1ty ot these enzymes end require atten... t1on~ The inYertase and maltase ot yeast (14, p,23) convert sucrose end the maltose produced by diastase into stmple sugars. Yeast ferments tnese sugars to alcohol, carbon dioxide and other b;y-produots by meen.s of zymase.

Factors At:teottns Enzge A.ot1Y1 ~z: The most distinc­ ti.ve physical property ot bread is the large amount ot aurtaoe, external and iuternal, in proportion to tbe mass. This g1Yes (36, p.l} larae surt.e.oe areas tor the action ot the enzymes. Small ditterences in enzyme action may, therefore, have quite an ettect in ripening the dough. 'remperature, moisture content, hydrogen-ion concentration, and the kind end concentration of the substrate etteot en­ zyme aot1-v1ty. The rete of enzyme activity (42, p.230) is greatly intluenoed by temperature. SUlllner (41, p.l3) states that w~th .1n l1m1ta a rise 1n te111perature increases the velocity ot enzyme action up to the optimum.. Above this, enzyme aqtion is decreased due to enzyme destruction• .Accordine to Sumner .(41, p .16) pH also has a marked etteot on enzyme action. Each enzyme functions best at a rather definite pH value. There seems to be a difference ot opinion as to the hrdrogen-ion concentration that is 18 best 1n terms of total doll@h development but most inves­ tigators (42 1 p.24) give an optimum pH or 5.0. Some work­ ers. however, believe that there 1s a range ot pH t:rom 4.0 to, 6. o wh1ob. ls opt.tmum for fermentation. Many substances present in doughs will aooelere.te the action ot the enzymes (42 1 p.232). SUDU1er (41, p.2e) states that this is probably due to the removal ot some poison trom the enzyme. The action or these subatanoee (42, p.232) is controlled b1 the presence or absence ot I acids in the dough. The e.dd1 tion of la.ctio aoid bacteria, leoti() acid, or other acids to the dough gives a more uni· torm.ly aerated 1 better flavored bread and causes an in­ crease in fermentation as. long as the optimum. pH is ·not exceeded. The moisture oon tent of the dough is known to e.rteot enzyme action. They en and Galloway (42, p.229) state tbat an increase or 30 per oeht 1n the water content of the dough increases the fermentation power of the yeast by 6.5 per oent, perhaps beoause ot 1nore·as•d diasts:tio ac­ t ion 1n the dough. Tbe amount and kind of 1ngre41ents used 1n the doup are very important. Sumner po1nts out (41, p.l2) that eaoh enzrme has an opt1mum am.ount ot substrate. It there 1a less or more ot tbe substrate the enzyme will not aot as quickly. The optimum amount ot substrate depends upon 19 the by4rosen-1on concentration, the opt.iaum. amount being lower as the hydrogen-ion concentration approaches neutral on the acid side. Regulating EnzW!e Activity: Enzyme activity may be regulated to a certain degree by controlling the te~ent­ ing, proofing end bald.ns coaditiona. Merritt and Stem.'berg ·(28, p.2B) state that the condi­ tions for proofing doughs vary considerably, depending on the rate ot gas e"f'olut1on inside the dough and the ab111 ty ot the dough to retain gaa. "It the dough has very little strength and poor gas-holding properties" or when gas evolution is slow, "the proofing rate should be lower and a longer ttme provided. Temperature and relative humidity should be reduced." It is generally recognized (17, p.3l} that time, tem• perature, and humidity conditions in dough proofing are important taotors in determining bread quality. The lack ot proper control or these tactors is said to be among the chief causes ot interior bread. The effect ot these three factors on bread was studied by Freilich (17, pp.33-34). The results indicat• a 'tairly wide range of proot time (40 to ~0 minutes) wi~­ 111 wbioh satisfactory bread might be produced. The range ot temperature tor optimum loaf quality was 86 ~ 115° r. and in this range the spread of proof times was about 20 20 m~nutes. Though Tariation in humidity aad no significant ettects on Tolume, texture and grain, loaves proofed at the lower humidities or 35, 50, and 60 per cent had light­ e.r, duller, more spotted crusts• while those proofed at the higher humiditi•s were more unitorm looking and darker 1n color. At lower humidities doughs proofed more slowly than those at 80 - 90 per cent hUD11d1t1es. The best re ... sults were obtained within the relative narrow range of' 80 - 90 per cent humidity.

In dough conditioning (8, p.5~), the temperature ot t~e fermentation cabinet oan be controlled more easily than the dough temperature. Since temperature affects ·en• Z}'llle · aot1T1ty in the dough, temperature regulation will result in controlled dough ripening and yeast activity. The dough continues to change in the oven, and these antioipe.ted changes must be considered when judging the adequacy or dough ripeness at the end or the proof' period. Burhans and Clapp ( 9, p.l96} explain the changes which occur during baking as follows. Oven spring takes place as a result of' taster gas production, turthe!' ex­ t,nsion of' the cell structure s\lbsequen.t to the softening ot gluten by heat, and trom the rapid appearance of' numer­ ous new bubbles in the walls of' the pre-existing ones. The rise in temperature increases the amount of' carbon dioxide released trom solution and causes the gas to 21 expand. During the initial period ot baking there is also an increased production or gas due to the accelerating ettect of moderately high temperature upon zymase and di­ astase. All of these factors combine to greatly increase the gas pressure within the loat. The rise in loat temper ture during baking tirst accelerates, then slows, and finally 1nact1Tates zymase at about 65° c. (9, p.l96). lermentation then ceases, but the dough may continue to expend due to the release ot dissolved gases and vaporized alcohol and water at the higher temperatures. Terminally, the coagulation of glu­ ten and the gelatinization of starch become complete and tix the structure. Lowe (26, p.440) states that in desirable doughs, ex­ pansion ceases during the coagulation ot the gluten. In undesirable doughs expansion may be arrested before coagu­ lation of the gluten begins resulting in collapse of the cell structure, Gas evolution during the early stages of baking is, therefore, ot prime importance.

Hydrogen-Ion Concentration

It 1s well reoogn1zed (11, p.27) that the hydrogen­ ion concentration is one ot the most t.portant factors in­ fluencing the characteristics ot baked goods. Its influ­ ence of enzyme activity has already been mentioned. It 22 haa many other important roles in bread making. Bailey and Sher1r0od (3, p.624) have called attention to the taot that pH is ot importance fo,r at least the fol­ lowing reasons: The iso-eleotric point of gl.ut.en, or the point at which gluten is the most coherent and elastic, is near pH 5.0. The optimal pH values ot enzymes which have been investigated tall around pH 5.0. Yeast fermentation reaches a maximum rate near pB 5.0. lf7drogen·1on concen­ tration is known to have a definite relation (34, p.S) to tbe tlavor of bread. Too high a pH is associated with laok ot tlavor end too low a pH is associated with the characteristic odor ot old bread. !he p:a. of bread dough ( 11, p.2'1) end ot the t inished breed ia due prtMar11Y to changes occurring during fermen­ tation rather than ·to the original pH ot the dough ingre­ dients. The initial pH ot the dough (e. p.54) when treshly ·mixed is approximately 6.0 but this varies with the ingredients. Ae termentation proceeds, the hydrogen­ ion concentration increases progressively. Acid production in doughs (21, p.23l) is due to these main reactions: (1) the pl'Oduotion ot carbon dioxide by the yeast, (2) tb production ot phosphate salts by the action ot phytase upon phytin, (3) the production ot organic ao1ds by yeast end other m1oro-organisms. 23 There is some difference ot opinion emng workers as to which ot these three t ctors exerts the greatest influ­ ence on the hydrogen-ion concentration or the dough. ET1­ dence has been presented (21, p.233) to support all three. The production ot carbon dioxide is a major taotor in lowering the pH but the full ettect due to the gas is achieTed very early in ter.mentation and further pH changes are due to other factors. Brown (8, p.24} attributes much ot the obange in pH to micro-organisms other than yeast. Be states that alcohol 1s converted to acet1o aoid, and sugar is oonTerted to lactic aoid by baoteria, thus lower­ ing the pH Talue. The bacteria responsible tor the aoid in the dough (40, p.238) are identical with or related to

Bact. aciditicans lonsiss~um, Later. Brown (8, p.29) states that lactic acid baoteri end acetic acid bacteria are always present in the flour. Ot the two acids, lactic acid 1s produced in the larger amounts and ionizes to a much greater extent. Hence, it plays an appreciably larger role in dough condi­ tioning. It bas already been stated that bread dough has an initiel pH ot 6. 0 and that a pH ot around 5.0 is optimum tor dough ripening. The production ot acid in the dough is, therefore, desirable. 24

However, certain factors in the dough may prevent a drop in pH value. The emount of milk solids (11, p.27) in the formula and tbe quantity ot gluten in the dough ( 42 1 p.234}, due to their buttering action, have a marked etteot on the pH of the finished b:tee.d. It was tound that the optimum pH took longer to establish in a dough w1 th hi.gh gluten con-tent (42, p.233). Dalby (11, p.2'1) studied the effects on pH ot different per cent levels ot dry milk solids in the dough. When 3 per cent milk solids were used a pH ot 5.37 was obtained at the end ot fermentation.

1th 6 per cent mi.lk solids, a pH of 5. 58 was obtained. A. pH or ·5,68 was developed when g per oent milk solids were

used. ·.· ~ ..:

Colloidal Properties ot Doughs ' Four dQ.ugh mixing methocls were u.sed tor the work re• ported herein. 'fhe })as1o structure or yeast leavened dc>ughs will be considered w1 th regard to the possible ettect ot vary1ng..m1xing methods. When flour is mixed with ·water (33, pp.27-28) the first physical action ot bae1c importance which occurs is the wetting of the flour particles. etting involves the phenomenon of adsorption 1n which two substances exert mutually attractive foroes whioh oauae one of the eub­ etances to adhere to the other• s surface. /

25

Baker, Parker. and Mize (5, p.30) define bound water

aa that portion which "oombi~ea with the flour constitu­ ents to torm. hydr tea, or ia bound by polar groups or otherwise reacted in such a manner that it is no longer ·available aa a solvent." As more and more layers ot water molecules are bound an.d superillposed upon each other (33, I p.28) those molecules which are farther removed trom the adsorbing aurtace are less and leas strongly held until a level is reaohed when 1t is ditf'ioult to decide whether a layer ot water is to be oonaidered bound or tree. Swanson (35, p.lO) explains the tunotions ot the bound and tree water in the dough as tollowa: The proper­ ty ot gas retention is due mostly to the water tilma ad­ sorbed or bound on the filaments ot gluten and the en­ meshed starch. The continued enlargement ot the gas bubbles wbioh results in dough expansion oan take place only it the gluten strands and starch particles whioh sup­ port the water films oan slide on each other. This slid­ ing is made possible by the greater freedom in the outer layers ot water, the tree water, adsorbed on the protein or gluten strands and starch. This tree water is a aaall part ot the total water added to the dough. This is why small ditterences in the total water added in preparation ot dough, or small dif'terenoes in adsorption make such 26 large ditterencea in the consistency or plastic behaTior ot the dough. Lowe (26, p.467) states that the extent or mixing a dough may alter ita Tiacoaity or fluidity. This suggests that the amount ot water bound by gluten and starch may ditter due to mixing method. Pyler (33, p.29) deaoribea the tor.Mation ot the glu­ ten network in the dough as follows: An apparently chemi­ cal union occurs between water and the protein aaterial leading to the formation of a three dtaenaional network ot Tery tine strands. As mixing is oont1nued the gluten strands or fibrils are stretohed and rearranged into a parallel pattern. At the same time the gluten fibrils are criss-crossed and wound about the starch granules produc­ ing a honey-comb effect of minute cella tilled with starch granules and air. Swanson (35• p.ll) points out that there is a certain amount ot elasticity in the gluten strands which enables them to recoil after stretching and permanently elongate it stretching goes beyond the elastic lt.it. At the stage of mixing when the gluten particles are parallel (19, p.20l), the greatest degree or elasticity and maximum resistance to pulling are exhibited by the dough, because at this point t~e greatest number of gluten "coils" are in a position to resist elongation on the one hand, and to spring back atter elongation on the other.

Mixing beyond this stage breaks down the dough by causing the rupture of weaker spring elements tirst, tollQwed b7 slippage ot the stronger gluten oo1ls past. eaob other and their eventual break. 'fhey thereby lose their strength and the dough. whioh is now overmlxed. beoomes at1oky and runn1. Opt~um mixing (38, p.43e) produces a dough wh1oh has the best gas·reta1ning properties. Frey states (18, p.22) tha.t proper tempere.tUl"e con­ trol during mixing is ot utmost importance. Optimum glu­ t•n development will generall1 be obtained with a m1J1ng temperature range ot 76 - 82° Y. The mixing and dough handling technique• may affect the final oell st~ucture ot the dough and the bread. The origin and structure of gas cells 1n dough has been stud­ ied ohieflY b7 Baker and oo ....workers. They report t•, p.l~) that most ot the gas cells in the finished bread originate during the mixing period. Gas 1ncorporation during mixing ( 6, p.39) did not proceed at an eYen rate but was slow at tile begitul1ng and most rapid at the point when the dou!ll otterc.d its greatest resistance to m1xlng. The best bread is obtained when mixing oeases just prior to the point of most rapid gas ooolusion. Baker and Mize (6, p.39) suggest that the tine cell structure ot bread is no,t obtained by gas occlusion during mixing alone but also by the subdivision ot gas cells dur­ ing the subsequent steps ot the baking process, such as punching and molding. These steps, while they do not in­ corporate new gas ,cells into the dough, create a greatly increased number ot cells by subdividing those already present and turther deTelop the gluten and tend to make it air tigbt so that the gas cells retain their integrity. Comparison ot the cell structure ot doughs and baked bread shows that all ot the cells tound in the bread exist in the dough when plaoed in the baking pan. The ditterenoes that do exist in the bread texture as compared to the dough are attributable to the ooalescenoe ~nd breaking ot cells during molding, proofing and baking. The mixing method may, therefore, attect the volume and cell structure ot the finished product, and the tech­ nique used in punohing and shaping the rolls may haTe an etteot on the texture of the finished product. Dittering Tiews as to the role of yeast in cell for­ mation haTe been reported in the literature. Baker end M1ze (7, p.l9) state that the yeast organism is incapable ot originating gas cella in the dough. They state that the gas senerated by the yeast dittuses into pre-existing 29 gas cella introduced during mixing. A somewhat different view w1~h regard to the role ot yeast in cell formation in dough is expressed by BUl'hans and Clapp. The7 round ( 9, p.l96) that while the reaat cells do not torm the tooi ot gas cella, the fermentative aotion ot yeast is largelf re­ sponsible tor the origin and tor.mation ot the cell struc­ ture of the dough and bread. They observed that carbon dioxide produced by the yeast cell at tirat remains in solution. As more carbon dioxide is formed, the Tapor pressure ot the gas in aolut1on increases until a weak point in the gluten matrix ,gives way and a gas pocket forms. continued oarbon dioxide production enlarses exist­ ing gaa bubbles by diffusion and the resulting tension r iaea the vapor pressure to form others. Baker and Mize (6, p.39) state that the role of fer­ mentation in the deYelopment ot texture ie principally one ot imparting proper strength and extensibility to the cell walls. Under-fermented doughs will oon tain as muoh air as will properly fermented doughs since the air was incorpo­ rated in the mixing. However, the oTer-ter.mented doughs will lack the strength to prevent coalescence ot gas cells during proofing and baking so that a rather ooarse bread texture results. The under•termented doughs poaseas a eiruoture whioh ia unable to wi thatand the severe action 30 ot punob1ng and mold1ns without breaking the gas oella and g1Ting rise to ooaraer texture. It may be seen, therefore, that n.riation 1n mixing methods, rate or oarbon 410X14e prQduotion, dough he.ndllUg methods, end ripeness o:t the dough may all atteot the cell atruoture ot the t1n1she4 produot. 31 CHAPTER III

BXPERDIENT.A.t .PBOOEDUD

Introduction

The expertmental procedure .., be described in gen­ eral as follows: Active dry yeast, together with dried milk, dried eggs, sugar, salt and Tegetable shortening were oremed together to tom. a m1x. The properties or this mix were evaluated through studies ot 1ts b·aktng per• torm.anoe when used ln rolls and through measurements ot yeast activity. A yeast Wh10h had not been incorporated in a mix was used a• a standard tor comparative tests. Hereafter, this yeast or products made with it will be re­ ferred to as "standard" whereas the word "mix" will desig­ nate products made wt th a mix. Preliminary work was carried out to establish r·ormu­ las and methods, to define the problems associated w1 th use ot this type ot mix and to susgest possible solutions. During the preltmtnary work, 1t was ·observed that yeast from different lots, as indicated by Tarious expira­ tion dates, lacked un1torm1ty. The roll, though prepared with standardized teehniques, Taried in texture and Tolume when made w1 th yeasts haTing d.1fferent expiration dates. I 52 These Tariations in quality ot the rolls were greater when the yeasts had ttret been incorporated in a mix. In th1s experiment • e·mph,asis ·was placed upon t 'he de­ velopment or a mi~ and methods ror preparation ot tbe dough

't~at would resul-t in bish quality rolls despite yeast Tar• 1ab111tJ.

Three lots ot active dry yeast were used. each baYing a ditterent expiration date. Yeeat dated April 15 was used tor Mix I; that d.ated S.ue l was used tor Mix II; and that dated lune 15 was u·secl tor l41x III. Yeast dated .rue 1 was also used throughout the experiment tor the "stand­ ard" roll with which the perrormance ot the mixes was com• pared. Prel1Dl1nary work turther 1nd1oatecl that the method &Dlployed 1n prepa.x-1ng a do\lib might influence the etteo,.. ti'f'en.esa ot this type ot Dli¥ in producing good quality rolla. 4fhree dou.sh m1x1ug methode were deTeloped tor use with the mix. Tlte•e ae\hoda ar• clesoribed in detail 1n fable 1 • page Z'l • It wae considered eaaentlal to determine the mixes' keeping qual1ties and the etteot ot the concentrated in.. gredienta on the yeast. The three mixea were. theretore, tested when treshly prepared and atter atorage at 1.5 ­ 4:.5° c. (35 - 4r0° F.) tor tiYe- and ten-week periods. 33 A number ot observations as to yeast activity and viability were carried out on the yeast which had been in­ corporated in the mix. Included in this group ot measure­ menta were oounts ot active and 1naot1ve yeast cells, pH value, and carbon dioxide production ot the mix. 'actors which might be attected by yeast activity and viability were dough response during fermentation, proof­ ing and baking. Intormation as to the relationship between yeast activity end dough behavior was sought through mixo­ grem patterns, determination ot pli, measurements ot fer­ mentation and proofing ttsea, and expansibility of the dough. The quality ot the dough in turn atteoted the quality ot the rolls. The roll qualitiea were evaluated by aoores and measurements of oroas-aeotion areas. Thus, the variables studied included three yeasts, three dough mixing methods, and three storage periods. Three yeasts, each having a different expiration date were used in the yeast mix formula. These mixes were studied at three storage periods (0, 5, and 10 weeks). Their per­ formance was CCIIlpered w1 th that of a "standard." Tbree different methods were used tor preparing rolls trom each ot the mixes. Three replications were carried out at each storage period tor each mix. 54 The design ot the experiment was a 3X3X3X3 factorial 1n randomized blocks, In order to reduce experimental error, the following conditions were controlled: lt18J,-ecl1·enta, formulas, mixing methode, dough handling techniques, tern1entat1on. prooting and baking oonditiona, equ1pl.lent used 81ld the teohniques tor taking measurementJ!J.

Ingredients

All ingredients were secured in quantities to last throughout the experiment. Borden• s Starlao milk powder ., Lyden's powdered whole eggs, Crisco vegetable shortening, and Morton's non~iod1zed salt were all stored in tbe1r original containers at room teD~:ptu:ature,. Spreokle •s beet 1uger wa.s stored in a tln oarmiste·r at room temperature. Fleischmann's active drJ yeast, in the original packages, was stored in a glees jar in tl).e retrigere.tor. fhe tlour used was Fisher's Blendaoo. It was a patent grade, bleaohe4, end enriched flour. It bad good water abaorp­ t1on and good gluten properties as oan be seen in the mix• ogrem pattern, Appendix, Figure 3. 'fhe 1ngJ'ed1ent.a for all ot the doughs were weighed at the beginning or the eXpertment. lor the -"standard" :roll, the dry ingredients, except tlour which was wrapped 1n aluminum toil, were wrapped ' .

35 together in waxed paper. They were stored at room t•per­ ature. The portions of tat were wrapped in waxed paper and refrigerated in glass jars. The mixes were prepared at tbe beginning ot the ex­ periment. Sixty-eight (68.0) grsm portions were wrapped in waxed paper and s tored i lass jars under refrigera­ tion.

Formulas.

The mix formula 1nolu4ed the following: auoroae,

3?~.0 grama; shortening, $52.5 grams; powdered egg, 135.0 grama; powdered skim milk, 320.0 grema; salt, 30.0 grams; and active dry yeast, 154.5 grams, Sixty eight (68.0) grams ot thia mix were oambined with 102.0 ml. ot water and 165.0 grams ot flour to make eaoh batoh ot dough. The "standard" roll dousb was prepared w1 th the same ingredients as were used tor the "mix" rolla. It has been previoualy mentioned that, ot the three yeasts used tor the mixes, one was also used tor the "atandard" rolla. The formula :ror the "standard" roll dough and that tor the "mix" dough were developed independently, Eaoh was de­ signed to produce tine quality rolls. A comparison ot the "standard" formula with tbe "mix" roll to1'111ule. showed that the amounts ot yeast • flour end water were the same, but 36 the "standard" contained slightlY lower proportions ot all the other ingredients.

Mixing Methods

The mixes were prepared by plaoing all ot the ingredi­ ent• 1n the mixing bowl ot the Kitohen-Aid and blending them tor 7 minutes at slow ·speed (speed 2). This was just enough mixing to thoroughl.y oombine the ingredients but nQt enough to incorporate m.uoh air. All ot the mix ingre­ dients were at roam temperature when combined. •our dough mixing methods were used; one tor the "standard" dough end three tor the "mix" doughs. A de­ tailed description ot eaoh is tabulated in Table 1, page 37. It will be noted that tbe staDdard, straight, and sponge methods are nearly identical, while the unkneaded method baa little resemblance to the others. The standard and straight methods dittered only slightly. The latter used the mix to tor.m a dough while the tormer used a~ilar ingredients but not in mix to~. The sponge method re­ sembled the straight method with just one exoeption. Atter halt ot the tlour was oombined with mix and water, the mixture was fermented in the sponge method before the dough was ooapleted. lor the straight method tbe remain­ ing tlour was added to the mixture and the dough was oompleted t.mediately. 37 Table 1 Methods tor Mixing Doughs

Mixer Tlie )tethod Ste:2 Ins.£edienta Directions s:2eed lMin.l 1 l/2 ot tlour Combine 4 7 'd All water, 30°0. coF-4 All other ins. 'd s:l Combine tlour co 2 1/2 ot flour with mixture ~ Cll to form doul!! Complete by ' 3 method, p.38 1/2 ot tlour l All water. 30°0. Combine 7 ~ 68 fP'8DlS ot mix ~ Com'61ne tlour ' ~co with above F-4 2 to ~ 1/2 ot tlour mixture Cll torm. dou" • Com.p1eie-., 3 aethod, p.38 1/2 ot t1our 1 All water, 30°C. Combine 4 7 68 srama ot mix 4) flO Ferment above s:l 2 mixture 0 PI Combine with .. Cll 3 1/2 ot tlour above mixture 4 3t to torm doufm Complete as 4 standard 68 1 grams ot mix Blend together 6 4 All water 1 52° C. . Combine with 2 above mixture 2 l/6 'd 4) Ferment above 'd 3 co mixture C> s:l Kne e.d above ..!od 4 mixture 4 2 s:l p Shape into rolls and 5 complete e.a ~~~D~Aisl For the unkneaded method, the mix and water were blended and the flour was mixed in just enough to dampen it. The dough closely resembled mut:t1n batter. This m1x­ tl1re was allowed to ferment after which it was kneaded. and shaped into rolls. All ot the mixing was carried on at room temperature which was maintained at 27° C* (eo. 6° F.).

Handling Met.hods Atter Mixing

Atter mixing, the dough was tolded lengthwise and flattened, then folded crosswise and flattened. This was r•peated three times to torm a smooth ball. The. dough was placed in a bowl, flattened, ligntly sreased, and incu­ bated at 30° 0. (87° F.).. Pans ot water •ere kept in the incubator to maintain a high humidity. The position of the dougbs in the incubator was randomized. All doughs were allowed to tennent until they held an imp:rint when lightly touched with a finger. A standardized hand method was used tor dividing the dough and shaping the rolls. The dough was removed trom the bowl w.i tb three motions. It was flattened between the hands and tolded lengthwise, then crosswise. This was repeated _six times. Eaoh batch ot dough wes divided into seven portions ot 40 grams each, and three 10-gram portions. Tbe latter 39 were \.\.sed tor pH readings. One ot the 40-.gram portion~ W$s used tor a test of dough expansion while the others were made into rolls. Each roll was shaped by the tollowing method: The portion of dough was placed in the lett palm. It •as tlattened and oppos1 te end.s of the dough sheet were over­ lapped e.nd sealed. This was repeated e.rter the dough was gi'Yen a quarter turn. The dough was then turned over ancl all ot the edgee were drawn to the under side and sealed. This gave a firm, well-shaped roll. The top ot the roll was greased by rubbing in a lightly greased muffin cup. It was then placed in the cup so that it was well centered and symmetrical. The rolls were proofed at 30° C. (86° F.) until one held en imprint when lightly touched with a finger and the visual appearance indicated that they were ready tor bak­ ing. Usually, two batches ot rolls were baked at a ttme. The rolls were be.ked at 204±1° c. ( ;59~f.t2° F.) tor 12 min­ utes. After baking, the rolls were imnlediately turned out ot the pan onto a wire cooling re.ck, allowed to eool tor about one hour, end then wrapped in aluminum toil and trozen. The rolls remained trozen until a convenient 40 time tor scoring, which was within one week ot the time or baking.

Equipment tor Preparing Rolls

A torsion balance and triple-beam balance were used tor all weighing. All mixing was done with a Hobart model K4-B Kitchen-Aid mixer using the standard beater blade. Speed settings ot 2 (slow), 4 (medium), and 6 (medium tast) were used.

The doughs were te~ented in 1-quart pyrex mixing bowls. A well insulated, ther.mostatioally controlled in­ cubator was used tor fermentation and proofing. Six-cup muttin tins having a shiny, hammered surtace were used tor baking. The rolls were baked in a heavily insulated Despatch electric oven having controls tor both . top and bottom elements. It was equipped with slots in the root which could be opened to aid in oven temperature control. The rolla and pH samples were trozen in a Bevco cab­ inet model treezer.

Equipment tor Measurements

A Beckman model G glass-electrode pH meter was used in determining pH ot the doughs and mixes. 41

A Warburg Manometer apparatus and flask were used tor measuring the carbon dioxide production ot the mix. Counts of actiTe and inactiTe yeast cells in the mix were made at a magnification of 450X by means ot an A.O. Spencer Bright Line Haemacytoaeter. Leitz microscope with a binocular tube was used tor making cell counts. An American Optical Company model 735G Microacope Lamp with an iris diaphragm 100-watt bulb, and a ground glass filter was used tor all microscope work. Mixograms were made by means ot a Swanson-Working Recording Micromixer in a ther.mostatically controlled cas& Cross-section areas of the rolls were measured by means ot a compensating polar planimeter.

Measurements to Determine Mix Properties

Twenty-two and six-tenths (22.6) grams ot mix were blended with 34 ml. of water at 30° c. (66° 7.) for 4 min­ utes at speed 6. This suspension was then used tor all ot the tests made on the mix. Two 5-ml. beakers were tilled with this suspension and the pH ot each was taken. The readings were made within 5 minu.tes after the mixing was completed. The pH Talue of the mix at eaoh storage period was considered t~ be the average of six readings (two readings tor each of three replications). 42 .

Atter the pH readings were teken, a .5 ml. sample of the mix was p1petted into the center well of the arburg

anometer flask. The tlaek was ~ediately att ohed to the manometer end the first reading taken. Readings were repeated at 10-minute intervals tor 240 minutes. The pressure was released after each reading. The difference between the reading at the beginning e.nd at the end ot the 10-minute period was taken as an index to the volume ot carbon dioxide produced. The Warburg Mano­ meter was operating within 10 minutes atter the mix and water had been blended. The tlask was suspended in air at 24° c. and was protected from drafts. One slide was prepared for the cell count. bit ot mix was placed on each halt ot the Haemacytometer. A small drop ot water and a large drop ot 10 per oent Meth­ ylene Blue solution were added and blended with each b1 t ot mix. A cover glass was applied to the Haemacytometer. The number ot stained and unstained cells was immediately counted. A ratio was calculated and used as an index ot the number of active and inactive ye st cells in the mix.

Measurements to Determine Dough Propertie•

The time in minutes required tor fermentation of each dough and tor proofing the molded rolls was recorded. 43

A 40-gram portion ot the fermented dough was used to stu4J dough expansion. The sample was packed into a metal cylinder which was then slipped into a 250-ml. graduated cylinder. Tbe YOl.um.e of the douS}l in the oyl!.n4er was read at 30-minute intervale tor 240 minutes. The differ­ ence between the first reading end each succeeding reading was the dough expansion. The cylinders were kept at room temperature ·and were protected trom dratte. For determining the pH ot the douab. 10-gram samples were taken when the dough was tirst mixed, after fermenta­ tion, and atter proot1ng. The samples were wrapped in alumin\lJD. toil and t"rozen at ·1'1.'1° o. (0° F.), until a convenient time tor making the test, when they were re­ moved from t~e freezer a few at a time. Eaoh sample was blended with 10 81l. ot tap water by means ot a mortar and pestle. Some doughs blended more quickly than others eo the length ot time tor ble.nding could not be standardized. Instead, all doughs were blended until they reached approx­

~ately the same degree of dispersion. Two 5-ml. beakers were filled with the m1:.ttu·re and the pB value or the sam­ ple was taken immediately. :auxograms were made to detern1'1ne the ettect ot dit­ terent ingredients on the 4evelopment and mixing tolerance ot the gluten. M1xograms were made of the flour. flour 44 plus each yeast (three expiration dates), flour plus in­ gredients other than yeast, flour plus ingredients includ­ ing yeast, and flour plus each mix at each storage period. For all ot these mixograms the ingredients added to the tlour were used in the proportion in which they occurred in the dough. To obtain a suitable mixogram pattern it was necessary to adjust the proportion ot water to compen~ sate tor the hydrophilic properties ot certain ingredients. A spring tension ot 9, temperature ot 27° c. (80.6° F.), ttse ot 12 minutes, and 30 grams ot tlour were used tor all the mixograms. A mixogram ot the tlour with 21 ml. ot water was first made to demonstrate the behavior or the gluten in the absence ot other dough ingredients. To determine the etrect ot yeast alone on the gluten, each date or yeast was used with the flour and 23 ml. ot water. A mixogram showing the ertect ot all ot the dough in­ gredients except yeast was made, using 23 ml. ot water. The combined etreots ot the dough ingredients and each ot the dates ot yeast are then measured. These were compared with mixograms which were made using t~e three mixes. For these, 30.9 grams or the mix­ water suspension prepared tor measuring the mix properties 45 was used with 4.4 ml. ot water which brought the total water content to 23 ml.

Measurements to Determine Roll Properties

Atter the rolls were baked and cooled, a typical sam­ ple or each batch was selected and cut in halt through the center to obtain a representative cross-section. The out­ line ot each halt was traced. The area was measured by means or a compensating polar plantmeter. Your reedings were obtained tor one roll. These were averaged and used as an index to the roll volume. The remaining rolls were stored at -17.7° c. (0° F.) tor approximately one week, until needed tor judging. They were then removed tram the freezer, unwrapped,

and placed ~n wire racks. Arter one hour, they were out in halves. Four rolls, comprising a complete replication, were judged together and usually two or these groups were judged on one day, one immediately following the other. The halt rolls were arranged .in randomized order with the "standard" always placed tirst and designated as the ref­ erence sample. The samples were coded and placed on sheets or waxed paper with the out surface down. They were coTered with paper napkins until they were ludged 1* to 3 hours after remoTing trom the rreezer. By this time they had reached room temperature. 46

The rolls were scored by a panel ot siX judges, tour ot whom had previous judging experience. The judges were tam111ar1zed with the eooring procedure during the prelim­ inary work.

The rolla were soored tor odor, color ot crust, colo~ ot crumb, cell distribution, cell size, crumb moistness, crumb springiness, and flavor. The "standard" roll was assigned a value ot tive tor each characteristic.' It the other samples were better than the standard they were scored higher, and it they were poorer, they were scored lower. The highest possible score was nine, and lowest possible score was one.

Throughout the exper~ent, observations as to the dough consistency, handling properties, oven spring, and other characteristics were recorded. Analyses ot Tarianoe were used tor roll scores and volumes in testing the signitioanoe ot ditterenoes among the mixes, storage periods, and dough mixing methode in order to determine the merit ot the different treatments. 4'1

CHAPTER IV

BBSULTS AID· DISOUSSIOB

Properties ot .the 141xes

Information as to properties ot the mixes was seclU"ed through m1xogram patterns, measurements ot pH, gas-produc­ tion capacity and counts ot active and inactive yeast cells.

Mixouam.s

Mixograms are designed (34, p.l65) to give a moving picture of the mechanical development ot the dough trom the time the water starts to set the tlour through complete development down to the breakdown ot the dough. The mixo­ gram furnishes a graphic means ot determining the proper­ ties ot water absorption, optimum mixing time end mixing tolerance ( 34, p.1'11) • Measurements ot m1xogram characteristics can be made as shown in Figure 1, p.48. At point A the dough has

reached the peak ot mechani~al development as indicated by the maximutll amount ot resistance to the moving pins ot the mixer. The measure ot line AB ie an index to the strength ot the dough end is designated "height to peak." The amount ot mixing required to develop the dough to its op­

timum strength is indicated by the length of line DA, 48

Figure 1. Location of Mixogram Measurements. XY Bottom line of mixograph paper. A Center of the curve at the highest point. AB Perpendieular to XY through A. C Starting point of curve. CD Perpendicular to XY. DE Parallel to XY through A. G Center of curve 2 minutes from A. E Measured 130 units* from A. EF Parallel to AB with F on line AG. AB Equals height to peak. DA Equals distance to peak. EF Equals extent of break. *50 units equal 1 inoh. Table 2 llea•urements ot Mixogram Patterns in Unit• ot 1/SO Inch

Heightl Distanoe2 Extent3 Kixogram ot Peak to Peak ot Break (AB) (DA) (EF_}

Flour 120 7~ 28 All Ingredients + Yeast I 125 13~ 22 All Ingredients + Yeast II 125 100 23 All Ingredients + Yeast III 111 132 15 All Ingredients Without Yeast 135 161 :38 o Storage MiX I 161 138 47 Mix II 151 156 32 Mix III 156 107 42 5 Weeks Storage lUx I 166 148 47 Mix II 161 158 59 lUx III 166 129 43 10 Weeks Storage Mix I 16~ 158 42 lUx II 167 139 50 lUx III 161 142 35

1 + or - 5 units. 2 + or - 5 units. 3 + or - 2 units. 50

called "length to peak." The line EF, called "extent ot break," indicates the rate at which the dough breaks down when mixed beyond its optimum strength. A larger extent or break (34, p.l9l) indicates lese desirable dough quali­

t1ea than a ~all extent or break. hen flour and water alone were mixed, the pattern indicated the formation ot a strong doush that deTeloped quite rapidly and had good tolerance to continued mixing. hen all ot the dough ingredients except yeast were combined the strength ot the dough increased, the time re­ quired to attain maximum dough deTelopment doubled, and the mixing tolerance decreased as sbown by a large extent ot break. The prolonged mixing neceeaary tor maximum de­ velopnent may have been due ·to the sugar end skim milk powder. Swanson (34, p.l91) found that sugar had this etfect but it did not influence the other mixogran measure­ ments. Powdered skim milk has been reported (34, p.l91) to increase (1) absorption, thereby increasing the height

to peak; (2) time to reach max~um dough development and (3) resistance to breaking. The results obtained in this

exper~ent agreed with this except that the tolerance to oYermixing was reduced. Nothing was round 1n the litera­

ture that would explain this. 51

The etteot or each yeast upon the dough properties was demonstrated, Appendix, Fisure I. The over-all ett'ects

ot yeast were: shortened mixing tbne tor maximum dough de~ velopment, reduced dough strength and improved tolerance to continued m1x1ng. Though mix1nc time required tor max1m.um dough developllent was appreciably shortened when yeast was included with all the other ingredients to t'orm a dough,

the t11lle was still much greater than that required by the tlour-water dough.. The yeast used in making mix II (yeast II) reduced the mixing time much more than did the yeasts

used in making mixes I and III (yeasts I and III). Yeasts I and II reduced dough strength, as shown by measurement ot the height or }»ak, to nearly that ot the t'lour..water dough, while yeast III reduced it still further. Dough tolerance to o'Yerm.l_xing improved with the addition ot yeast to such an extent that 1t surpassed the f'lour:-wate:r

dough. Yeast III caused a considerably greater improve· ment than the other yeasts. These findings are not in. agreement with those re­ ported by swanson (34, p.l71} tor compressed yeast in t'lour-water dough•. Oom.pre$aed yeast markedly decreased the rea1stanoe to breaking, but had little ett'eot on the t1me to reach maximum dough deYelopment, or on the absorp• tion. 52

hen the ingredients oonsid red above were combined in mix torm the mixogram patterns were altered. Appendix, Figures I, II an4 III. The measurements ot these mixogrem characteristics are given in Table 2, p.49. The ettect varied w1 th mix. Tbere was no change in the strength of the dough but the time required to obtain maxilllua dough developaent increased 56 per cent when mix II was used, while mix III reduced the time 19 per oent and mix I had no etteot. All ot the mixes decreased the tol­ erance ot the dough to overmixing. The extent ot break due to extended mixing increased 39 per oent, 121 per cent and 180 per cent tor mixes II, I, and III, respectively. Differences in mixogram patterns arising trom use ot the mix cannot be explained on tbe basis ot ingredients used, since the oomposition ot the doughs was the same tor all patterns. Differences in water absorption and in tat dispersion due to the order in whioh ingredients were com­ bined may have aome bearing on the changes. The mix was blended with water betore tor..ing the dough, thus giving the dry ingredients greater opportunity to rehydrate. In spite ot this, 1t does not seem probable that the differ­ ence in patterns ettected by the mixes were due to differ­ ences in absorption. It has been reported (34, p.l90) that the height to peak varies inversely with the fllllOunt 5S ot water 1D the dough. Inoreaaed absorption by the mix 1nsred1enta would, therefore, have resulted tn an in­ oreaaed height to peak. This was not the oase. The pos­ sibility exists that the mix ohanged the water absorption oepaoity ot the dough itael.t. HoweYer, no evidanoe was round to support this postulation. A ditterenoe in tat dispersion may be an 1ntluenoing taotor. Swaneon (3'• p.2ll) states that emulsions ot tats have important etteota on aimgrem. patterns. tfhey 1n­ oreaae the tiae ot dough developaent and inoreaae the tol­ eranoe to overmixing. An eaulaion oould be formed when the mix and water are blended prior to tom1Dg the dough. It auoh were the oaae, it oould explain tbl inoreaae in mixing time. It would not explain, however, the loaa in mixing toleranoe. further tnveatigation ia needed to de­ termine the reasons tor the mix etteot. The etteot ot the Dl1xea Ohe.nged aa they were stored. lor mixes I and III the tolerance to mixing tended to im­ prove after 10 weeks or storage. Dousb.• made with mix III tended to iaprove alightl7 more than those made with mix I. Mix II doughs had quite ditterent properties. After this mix was stored 5 weeks and to a leas extent after 10 weeks the doughs demonstrated a loss ot toleranoe to overmixing. The ohange in toleranoe was tnveraely related to the ratio ot otive to lneotive· yeast oells, i.e., aa the 54

number ot actiTe yeast oella decreased during storage the extent ot break 1noreas•4 {figure 2, p.55). DaTia and frenkel (12, p.llO) state that many workers haft shown with mixograma a sot-ten1.ag etteot of dead feast on bread dough similar to the aotton at reducing substances suob as gluta­ thione, Both tena to shorten the mixing time end decrease the dough to·leranoe to •••mixing, The strenath ot th' 4&U&ht as indicated b7 the height ot peak increased somewhat all the mixes were sto:ted. K1X II eXb1b1ted a greater increase in ita dough strengthezt1na etteot than the other mtxes. Mix I also increased dough strength While mix III increased the dough st.rength quite m~rkedl7 atter c; weeks storage but lost some ot its etteot atte:r 10 weeks ot storage.

The time requi~d to develop the dough to its tull

stz1n1gth obanged as the mixes were etored, doughs made trom mixes I and III requ1l'in8 longer mixing times after 10 neka storage th811 they did at o weeks storage. Mix II doughs required shorter mixing times atter 10 weeks tb.an at 0 storage. The mixes etteoted the mixogram. patterns q\11 te marked­ ly, their etteot changing with storage. Some of the mix

etteot may l>e attribute ~ .§ 0 tl 10 140 1 •>rl +> .. · ~ ,.0 f! c: IXl o-i ,·fo.-4 o '&> ' ~ > orl 5 ~ 0 lO 12011 0 s ~ Storage - Weeks

Plpn 2 llelatioubip of ActiYe/IaactiYe Y•n Cella te lxtent .r Br..t Ia ~ Patt.ru 'Dur1nc atarac•

<1 • • 350 2)00 r:: • i ·"' • ~ ....a +> 250 .noo..,.fi u ~ 'B l: _ ...... _ 1_ ' t. ~ '1 0 ...... 150 1900. ~ ~ I D m 0 ... Mix ... flpn l lelatiiUhip et \lie lota1 CU'bea •.we rr.a.u. te tM T$1 hnl.taU• ftM .r ... Mlz 56

·carbon D1ox14e Production. pH Values, and Ao~ive ge~l gopt

Carbon 41ox1de production, pB valuee and ratio ot aot1ve to inactive yeast cella are shown in Appendix; !.ABLE I. The mixes methylene blue ate.in doea llO t ·differentiate between dead cells end dormant cell.s which are &li'V'e but not respiring. In spite of these drawbaoke (23, Chapter '1, p.3), the method has been OODside.red satisfactory by many workers. 5'7

In this experiment; the ratio ot stained to UD.atained cella Yielded 1ntome.t1on tha' appeared to be related to

other t~n4 · 1llgs. i.e., exteDt ot break ot m1XOB81l'l patterns and total carbon dioxide produotioa ot the mixes. The

mixes 41tt'e~e4 1n thej.:r oonwnt or act1Ye yeast cells whtn they were first made, end they responded differently to atore.se. When ti:rst prepared, mix III bact tbe highest pro­ portion ot active cells although mtx z-r had nearly aa maDJ., While atx I had the lowest ratio. As mix I was stored the ratio deoreaaed steadily. lfhe nUJaber ot active oella in mix III 1Dorea•ed stead117 during storage. Mix II tluotu• ate4 in aot1ye cell oount a• it was stored, showing a de­ crease a.tter 0 ...eke storage and an 1no:reaae at the end ot 10 weeks storage. fl:le b.74roaen•toD oonoent:re.tion ot eaoh Jlllx wa• aeas• ure4 at each storage period. A. sl.1&ht trend was observed toward an 1Dorea•e 1n pB Te.lue or the mix during •torage; however • tb1a may uot be •lsnltS.oan,t. It was alao found that ll1X Ill ha4 a sl1ghtl7 higher aTerase pH value than 414 mtxea I and II.

:Dougba

Prootlna !&!!• !J!d Total J'ermentat1on Time

'l'he mixes 'f'atr1•4 in their ettect on prootiua and total fer.mentation ttmes required by tbe doughs. The average proofing and fermentation times ·ar giT n in Appendix, TABLE II. The doughs made with mix 1 required long r proofing and total fer-mentation times than did the doughs made trom the other 1xes. Doughs mad trom mix II required a short­ er proof period but qualled mix III in total fermentation period required, The a.,erage proot time and fermentation t1mes in­ creased with storage both tor the standard dough, made with yeast II• rut tor doughs made w1 th the mixes. Total fer­ mentation t~es for the yeast II standard dougns may be compared with yeast II 1x doughs. The standard dough in­ creased 10 minutes in proof time and 20 minutes in total te entation ttme, while mix II increased 5 inutes 1n proot time and 25 minutes in total fermentation t~e. This leads to the conclusion th t torase in contact with the oonoentrat d mix ingredients did not adTers ly atfeqt the yeast. 1xes I end III required 10 and 20 lnutes ore proof ti e, respectively.

The total ter.mentation t~e ot doughs ade with the mixes appeared to be in? rselY related to total carbon dioxide-producing capacity ( tgure 3, p.55). That is, ae the gas-producing capacity ot the mixes deoreased the total te~entation time r quired by doughs made tram 'ham increased. The method used in preparing the dough atteoted the proof time and the total termentation time. .A.a will be recalled, the dough preparation methods employing the mixes were sponge, straight.and unkneaded methods. The standard dough made with yeast II required leas total fer­ mentation tt.e than the doughs ade with the ixes although it tended to take longer tor proofing. The unkneaded dough required leas fermentation time than doughs made by • the otber methods. Unkn aded and sponge doughs required least time to proof while the straight doughs took auoh longer to proot than the standard. Because ot the short­

er fermentation and proofing t~es, the rolla ade by the Unkneaded method were ready to ·bake before the others.

This ••7 have been the result or more rapid initial en~· activity ln this dough due to two taotora: (1) the high temperature ot the water blended with the mix which oould

at~ulate the yeast and result in more rapid enzyme aotiv­

i ty 1 ( 2) the larger amounts ot tree water present 1n the unkneaded dough which would also per.mit more rapid enzyme activity. The unkneade4 doughs were properly ripened at the ttme ot baking, as indicated by their smooth, plump appearance prior. to baking and their excellent oven spring• This aupporta the theory that enzyme activity was more 60

rapid in the unkneaded dougha. Dough deTelopment and gaa pJ'Q4uoti.on both reaoh a maxhlura at oerta1n JllODlenta during

the teraentatlon ot tbe dougb (15, p.~74) and in order to obtain the beat 'baking reaulta the momenta when these au­ 1Dla are :reaohed ahould oo1no1de. Th1a apparentlY waa the

oaae tor the unkneaded dougha under ~e oonditiona ot thia experiJijnt.

With atorase ot the 7eaat and ot the m1xea, maxtaua expana1b111tJ of all ot the 4ougha waa reduoed. Atter 5 weeka storage ot \he mtxea there waa a aharp drop 1n ex­ pana1b111~ aoooapanied by a aharp 1noreaae tn the leng~ ot tiae required to reaoh the aaxiaUIIl expansion. No fur­ ther ohange in dough expana1b111ty waa noted at the 10­ week 1torase perlo4, although tbe time required tor maxi­ au. expanaion deoreaaed aoaewhat. A poa1t1Te relationship existed between dough expan• 11on and oarbon dioxide produo1ng-ab111ty ot the mtxea aa they were stored (Fteure 4, p. 61). As the gaa produotton deoreaae4 during storage ao 414 dough expansion. Tbia 1a

ln agreement with swanson end Swanson· (39• p.43~) who atate tbet gaa retention ot a dough 1a greatly lntluenoed b7 the gaa produotion. 61

0 1~() l JSo •

N ~ 0 ..c: ....CJ ...,.. 150 1250 l 0 ~ 0 s lO Storag-t> - 'wt"(" k e l1care 4 Relationship of Total Carbon Dioxide Production to Dough Expansion at l&ch Storage Period

0 500 o 450 D 13 50 a ~ f) " f) • ..., ~ rl ..-t ..-t ~ s § I c 1300 ~ ~ 47S I 42S Ill c p., 0 ""0 ~ ..., ..., ~ ..., ..c: ..c • b!J .r: +' ~ 450 3bOO 12')P ~ ~ 0 s 10 Storqe - Week•

P1.pre S Relationship Durinc Storace ot Douch lxpanaion to Mixogr• Me&sur•ent•J Height to Peak aDd t.Dgth to Peak 62 Dough expansion was inversely related to the m1xogram patterns obtained. It was round that the stroneer dough and those requir~ng longer mixing time ElB 1nd1oe.t•d by the mtxogrem pat.tern 1fel."e the ones the.t s.howed lese expanal• b111t7 (Figure &. p .•61). The dough mixing time used thl'oughout na established at the beginning ot the exper1ment on the bae1a or optimum .dough 4•velopm.ent. Atter storage ot 'the mix••• opt1m\Uil dougb 4eTelopment required lollger mld.q, as shown by the :ra1xogrems tor mixes I and III and leas tor mix 11. Hence, at the end ot the storage period, the doughs troa mixes I and III m$1 baTe been un4erm1xed end doughs trom mtx II may have been o•ermixed. Evidence wae tound to support this oonoluaioa in regard to mix II. Swanson (34., p •.214) states ~hat overmixed doughs reault in a decrease 1n loaf volume whioh is also a1gn1t1oantly oorrelated with a large weakening engle ot the m1xog.r811. This relationship was round to exlat for mlx II rolls. Tbe1r •olume•, as illdioated by ~ross-seot10n areas; decreased as the mtx was etored. At the same tiltle the weakening angle of the mizo­ gram ;pattern tnoreaaed (ltgure 6, p .•63). This leads to the oonolusion that mix II dough$ were probably overmtxecl. Swanaon (a4, p.l95) state4, howeyer, '".Inj\U'f due to oYerm1x1as if not too severe ms:t be repa1re4 cluring tar• mentation and Ul'ldel'Dl1x1ng m.ey be oompensated for bf the 63

0 ~ ~10 29,000 H § H .. H H ~ .... ~So.. 21,000 ~ 8 ..-4 +) !' ' u '--4 0 ~ e •I iJO 2$,000 ~ +> . 0 $ 10 l3 ~ Storage - Weeks

ripre 6 Relaticubip of Roll Orosa-a.ctiCD Ana to Mixograa lxtent of Break for Mix n at Each Storage Period

0 ~ a so~ Q/0 tlJSO ~ t J ~ ­

§ '"ris . l3 1950 1)00 IQ ~ ·[ . ~ ~ E ..c:: II 6 rz.. r-1 I .!'! 17 1250 0 0 $ lO ~ · Storage - Weeks

P1cure 7 Belationahip of Doach l:lpansiOD to fetal Fer.•tation 'Hu at &acb Stora1• Period meohan1oal aotion ot expansion during fermentation." !he deoreaae 1n dough expansibility following atorase ot the atandatd yeast and mixes was probably due 'o laok ot optt.ua mixing ot the doughs and to lower gas-produoing ability or the yeasts. Doush eXpansibility and total fermentation time were iaYerael7 rela,ed (figure '1, p. 63). Aa dough expansibilitJ 4eoreaaed atter storage ot the mixes the total fermenta­ tion t~e tnoreased. The relationship may be explained on the beaia that both are 1ntl~enoed by the total gaa produo­ tion ot the mixea. final pH ot the DOUghS

The bydrogen•ion oonoentration ot •aoh dough waa taken when 1' was t1rat mixed • atter 1t had proofed• ancl alter it had ter.aente4. ~heae data are a~artzed 1n AppeD41x, 'l'ABLlt IV. The pB ot the doughs atter ter.mentation depended pe.rtlJ on ~· mix from whioh tlle dough waa made. Doughs made trom a1X I had the highest final pH •aluea while those tor 1x II doughs were slightly lower than tor mix III dougha. The final pB •aluea tor these doughs were 1nnrae17 related to the maxim.\D expansion ot the doughs (Figure 8, p.65). !he dough mixing method also atteoted the t inal pB. Unkneaded and sponge doughs tended to h••• 65

.6950 l.LOO~ • () 'i1

;I; P. 6 oM .s.: 6900 1)00 ~ l ~ 6 r-1 i 4/ 0 -'= ~ 6850 1200­l I II In Mix lipre 8 Belationehip of nul Bouch pH to Douch hpaneion for Bach Mix

q

0 A c:• roo 2150 ~ ~/ t) 0 ~• ;I; 8 p., 6900 19SO ~ .c ., l· 0 I ·rs..• r-1 ~ 6Boo ' 17~ ~ 0 s lO ... Storace - 'Weeks

P1IUft 9 · &.lationahip of JiDal Doqh pH to Total l'ena•tation 'l'iae •* laob storaa• Period · 66

lower pH va.J.ues than the standard and straight doughs. fhe lower pH ot t,n.e unkneaded douS)ls in ap1 te ot their shorter total termentation time oan be explained if the

theol"Y ot lllOl"e rapid enzyme e.otivlty in these douses is aooepted. The lower pH values of the sponge doughs can be e~lalned by their longer total te~entation ttme. The straight dougbs had htsher pH 1'&luee than any other methe>ct. At the storage periods, the final pH Talues of the doughs Clroppe4 as the total ferntenta:tion. t1Jrie increased (J'tgurt 9. p .. 65).•

Rolla oresa.Seotion Areas

S1sn1t1oent ditterenoea were found by meens ot the e.nalys1a or TU1e.nce tor orosa•seot:Lon ereas, Appendix, TM!LE IX. The volum.ea. a.• indicated by oross•seotion areas, 41tte:r•4 when rolla were made by different methods, when made with the yarious mixes, and when the mixes had been stored.. Ktx llX produoed rolls with s1gn1t1oantlY larger oross•aeot1on areas than J;"Olls made w1 th ml.~es % and II. 'l'he rolla made w1 th mix III remained about the saae throughout the etore.ge pert·od. The orosa-seotion areas et rolls made with mix I and 11 changed as the ~1xea were 67

etored, the ex.ten.t ot change differing .with tbe mtx. Atte:r 5 weeks of storage, mix I yielded smaller rolls. No cleorease took place with turther storage. Mix II :rolls

increased in area atter the m1~ was stored 5 weeks and re• main.ed unohe.nged at the 10-week period. For mixes 1 and 11 the uukneaded method gave rolls having oross•aeotion anae s111l1lar to the standari and eignittoantly larger than rolls made by the speage or straight methods. For mix III, both the straight and un­ kneaded methods z;esulted in rolls hartng larger oro as... section areas than the standard roll. The standard, in turn- was s1gn1t1cantlJ larger .in area than the sponge roll. Sterage ot tu mixes 414 not change the above­ mentioned l'elat1onships" ot. the dough pre:pat'&t1o:n methOds. In eaoh oaae, the unknea4e4 mtt'thocl reeW.ted 1n rolls eque.l in TOlume or superior to the standard. Good clougb eqan':'" s1b111ty (figure 10, p.&e), shOrt fermentation tlme

(Figure ll, p.68), and 'oleranoe t~ overm1x1ng as shown by m1xogram patterna were asaoo1ated with sood roll volume.

Palat1l?1l1)l Soores.

The scores tor eao~ ot e1.gbt ohare.oteristtoa eTalu· ated by ihe judges were analyzed separately by meens ot the analysis ot Yar1anoe, Appen41s:, T.AB.L'E V. Average 68

0 • ~ : 1;1 84'000 1300 8 ~ .• 2 ~ ' ~ - j so,~..- -~---n-~-m-..6 l2lio l Jllx P1pn lO lalatiauld.p of Cro•...S.Ctima Area To DOach hpntdoa lor laoh Jib

Q

~22 000 750 I I 0 ·II; .. 1-4 ·! q ••I) -~ /A &. i ~1.. j 20,000 :.~ . ~ .550 1ti . I I) s lk.l-4 "ri ~ ~%---~ 2 . "/18,000 • l50u : . 1 2 0 lJ ~ Method• Pi«Ure 11 ~Uauldp ot OrM8-I.oU• Ana to Tetal rm ,.,.u.aa n.. ~ loll• Prepancl b7 Pflllr lltrl. lletW• rrc. JUn• I aDd. D

• Mixinc Method 1. Standard 3. Straicht 2. Unkawded 4. SI>OIIC• 69 scores are s1ven 1n Appendix, TABLES VI, VII, and VIII. Se'f'eral ohe.racter1st1oa w re atreoted in a a1ll1lar way 'b7 the Tariablea under study and are olaeaU'1ed aooor41nsl7• _ Cell Distribution and Cell Size: The method ot prepara­ 'lon, the mix used end storage ot the mtx atteote4 the soorea tor oell size end oell distribution. The unkneaded method produced rolls scoring s1gn1tioantlr higher than those mede by the straight dough method 1 whioh in turn aoored a1gn1t1oantly higher than tba sponge rolla. The standard rolla were similar to those aade b7 the u~eaded and straight dough methods. Cell size soores giTen rolls aede tram mix III were s1gnit1oantl7 higher than tor miX I, whioh in turn were hiper than soores tor mix 11.

Aa the ~ixe s were stored, oell en atr1b ution aoores ohanpd tor rolls made trom atx 1 and II. Mix I rolls re­ oe1Ted lower soores and mix II roUe high~r aoores when made trom aix.s stored 5 weeks aa oompered wlth treahlJ prepared aix. Their scores did not change further at 10 weka storage. Mix III rolls were judged about the same throu@bout the storage period. Doty and Urban (13. p.:S4} toUDd a relationship be• tween the rate ot gas produot1on of moi.st yeast e.nd the texture and oruat obaraoteriatios Qt 'bread. In thle ex• per1ment, oell size, oell distribution aad oruat color 70 ap})4tared to be unrelated to total gas produotion. Sprirlsineaa and oistnesa: The dough mixing me·thod

atteoted the aoorea to~ these two oharaoteristioa.. The standard and UDkneaded rolla reoeived higher aoores than the sponge rolls. The atra1pt aetboel produoe4 rolla

wh1oh were judged better than tbe a~nge rolls but similar to the unlmeaded rolls. ror ,springiness, tlMI apoJl8e rolla reoe1Ted lower soorea than the straight rolls, but there was no ditterenoe 1n soores tea 1atness. Both springiness and moistness soores varied with the mix. lUx III rolls were soo.red sign1t1oantlY higher than the rolls made with mixes I and II. Storage ot th mixes did not oause · a d1tterenoe in roll aoorea tor springiness or moiatne•s and did not ohange the etteot ot the miXing m.ethodl or the aotion or the mix. Springiness and moistness soores were related to total tementation times ot the doughs. As fermentation t1Jile increased, soorea tor these roll oharaoter1st1os deoreased (Figure 1a, p.71). Cl'UJlb Color: · No sign1t1oant ditterenoe was found be­ tween the soores tor orumb oolor reoe1Ted by the standard. straight and Ullkneaded rolls. The sponge rolls reoeiTed sign1t1oantly lower soorea than the other rolls. The aoorea given rolls made from mixes I and III did not ohange s1pitioantl7 as the mixes were stored. J&lx II 71

0 () -:3 .,rl • 1-. ID 0 ;lAX) 2(X'( ) t) 30o f ~ ID 0 t)... ., ID ID ., ID ~ c: .,ID ~ c: s ~ 700 ~150 16cx> ... ~ !!.. ~ ~ · .c:, e., ~ ~ ea.. u 0 ...... 0 r; /.('(, 12(l(l !! ~ ?00 0 1) f-4. 1 a 3 4 f-4 f-4 Mixing Met hod * Figure 12 Relationohi.p ot Total Craab Springiness Scores to Total J'emeotation n.e ol BoU. Prepe.Nd. 'b7 roar Doqh Mix1nc Method•

JOO 750 .. 0 .,

10 ~~f-4 •• .s.., s.. 0 B • 0 t) ...... ll ~ ~-a 8 .. 26o 55fl ~ "' · H n4 C:H .QH CIH . ~ I .,f I OH f&.H rl. ~i4 .:!r-ill ., ~., b E-• ~ 220 150 ~~ 1 2 'I 4 Mixing Method * J'icure 13 Relationahip ot Total Cruab Color Scorea to Total Fe:naentatiOD Tille ot Bolla Prepared b7 Four M1x1q Methode tl"aa Mixea I ADd II

* Jlfixing Method

1. Standard 3. ~ traie!'lt " . UnknNded u . Sponr,e '12

rolla scored s1gn1t1oantlf higher atter the m1.x was stc,.red

{ I 10 weeks than they did when the mix was freshly prepared. The erumb oolor scores received by rolls prepared from mixes I and II (all llliXinS meth.ods combined) decreased atsnttloantlJ as the dough t•:rmentatton t1m.e iaoreased (Figure 13, p.'11). 'fhe oolor of orlll'b (22, p.ll9) 1s Ulatn•

17 controlled by tbe oolor ot the .flour, but 1 t oan be 1n­ tlueaoe4 'by the fermentation treataent. Over•ripeness. tor exuple• tends to gift a du.ll grey tinge. The teJilper• ature ot fermentation was held constant throughout, so that aa the temen\ation time increased more extensive en­ zyme eot1Y1ty occurred, Tbe judges, men tto:ned the tollowing tra1ts ot rolls made 'by the straipt method tl'oa miea I end II; ooaree cell a1ze, sogglaeaa. yellow er\Dlb, 11wet taste and red orliat. 'l'heae oharaoterlstioa (l&, p.2'1) 118,7 result from an under-ripe dough. The following oomments were made about the apoage method rolls ma4e from all mixes: yellow orust, greyish or brownish orumb• oompaot cells, and laok or odor and tlavo:r. All these oharaoterist1os .(22, pp.86• 8'1) llay result from over-ripe doughs. 'l'h• probable oaue '· ot the latter may be too loas a total fermentation t~e.

Odozo:, f .lavor e~d Crust Color: Bolls made from mix III were eoored s1gn1ticantl7 bette·l' 1n odor and flavor than tho.ae m.ad.e from mixes X or II. lUx I rolls did not ditter '13

in the •• oharaoteristica troa the mtx II rolla. Oruat oolor 414 not 4itter due to mix uaed. Storage ot the mixea taTorably attected the flavor, odor and ·crust color scores tor the rolls. These scorea were signit1cantl7 higher atter· the mixes had been stored 10 weeks than ther were when the mixes were freshly pre­ pared. The mixing method used produoed aome ditterenoe in scores. The standard and untneaded methods produced rolla aoor1ng a1gnit1cantly higber tor odor and crust color than rolla made bJ the straight and sponge methods. -!here was no real 41tterenoe between the aoorea received bJ rolla made by the unkneaded ·an4 standard methods. nor was there a difference between the etralght and eponp methocla. ror mlxea I end II• the Ul'llmeaded method produced rolla with a1gn1t1cantl1 hlghel' aoores tor flavor. o particular method appeared to be beat tor m1x III. Odor aoores tor the rolla made bJ different a1x1ns methods were inversely related to their total ter..enta­ tion time (Figure 1•. P•'•>• as were their flavor scores when mixes I and II were used (Figure 1&, p.?4). The iaprovemen t 1n odor end tla-.or durins storage was related to the drop in t:lnal pB values of the ctougha (J'igure 16, p.'11). 74 <3...... ~ 800. 2000 E 0 A "· "I! s... ~ c" () ~ ~ 0 "'"" -rl I 750 16oo ~ s... ..~ 0 '­ (g • A/ E" t> r-4 s. ~- 0 A/ r-1.. f--<700 ~ 1200 0 1 2 3 . !.. f-< .Mlximc Mathod • Fi«ure 14 R.elationship ot Total Odor Scores to Total Feraentation Tiae ot •11• Prepared by .Four Mixing Methods • .. . . ~ 11:1 .300 ~ E .. " H f:!O H c • 0 c: ~i

'S:H .. sso tlH .,E I ~H

~ IQ t ~ ~ - 35o...... ,o__...... - .....--_..200 ~ 1 • 2 J. 4 ~ 1'1ixing Method • .,. · Relationship o! Total n.&Tor Scores to Total rera•tatiCIID T1ae ot Bolls Prepared by Four M1xing Method• ~ Mixes I aDd II

· • Mi.xi:nc Method

1 . Standard 2. Unkneaded 3. Straicht l. Sponge ?5

0

7000

I J-4 0 &:= "01000 i J-4 0 ---·

·F1pre 16 a.l&tiClllabip of Total Odor. aDd n.uor Scores to Pinal Doach pH at lach Storace Period '16

Oruat oolo:r (22• p.ll8) 1a most17 conditioned br the amount ot sugar remaining in the 4ouah whtn 1 t te pu._ 1n­ to the ov•n and b7 the oven oond1t1oaa. Though tbe aaount ot sugar in the dough deoreaaes as te~entation 1s pro­ longed, aoores tor crust oolor obtained in tbi.s expexoiaent had no apparent relationship to the total teaen,at1on ~,... '17 OJJAP.rltR Y

SliOIAlll' AND OONOLVSIONS

A readr·mix whtoh may be prepared and stored tor the future preparation at s•••·t ..yeaet•leaven·ed goods has been developed. The yeast 1s blen4ed W1th the dry ingredient• 1nclud1ns shorten1ag.• suga:r;", dehydrated m1lk, 4ehyclrate4 eggs a4 aalt. Plour is omitted 1"roa tht• blend. The purpos.e ot this ia-reattsation wae to detel"Dline wh•ther (1) the mix p:roduoe4 pod.s ot satlstaotorJ qual1• ,,., (2) storage atteotecl the a'otton ot the mix• (3) one dough preparation method woud be bettel" than another 1n using the mix and (4) yeast var1a'b111 ~1 would alter the etteot1veness ot the mtz. To this en4 the tol'Jilula wea prepared us1QS three dates ot feast. The three mixes were then stored in the retr1serator. Atter the mixea were treellly prepared, atter a 5-week storage period end again after a lO•week storage period, portions ot these mix·•• were used tor the · preparation ot sweet-yee.at...leavened :rolla. Three doqh preparation aethods were uae4 •1th eaCh mix at each ator• age period. Performance ot the mix was eTaluated thl'ough studies ot 't;he (1) yeast • ( 2) doughs• and ( 3) tlnished rolls. The doughs and t1nished rolls n~e compar·ed with the 78

pertor.manoe ot aot1Te dry yeast whiob had not been incor­ porated in a a1x but which was stored tn the refrigerator.

The yeas~ incorporated in tbt mixes waa studied as follows; fhe proportion ot T1able to non-Tiable cella na determined by miorosoopic obaerYation and oounta; gas pro• duction waa measured on the Warburg manoaeter; pH measure­ ments were taken. The quality ot the doughS was studied by means ot pH measurements, fermenting and prooting times, measurements of maximum expansion, and mtxosram patt.erns.

the quality of the rolls was e'feluated by means of judges• soores and through measurements of the cross­ section area. The mixes were found to differ in their aot1on due to yeast Tariab111ty. The reaats Tar1ed 1n their carbon dioxide producing oapaoity and their ratio ot aotiTe to inactiTe yeast oellah This oauaed d1tferences in the dough properties aa shown by the mixogram patterns, fer­ mentation and proofing times and dough expanaibility.

Despite this Yariabilit7 1 all three mixes, when freahlJ prepared end when sto~d at refrigerator tempera­ ture up to 10 weeks, produced l:'olls of good quality. Storage or the mixes and or the standard yeast re­ sulted 1n a decrease in total carbOn dioxide production whioh was reflected in: an increased total fermentation 79

t1Dle and time 1iO reach max1JDum. douah expaxut icD.; deo:reaae in dough expana1bil1ty; deoreaae in oro.ss... seotioa areas or rolls; and lowered final dough pl. Changes wb.iob. occurred 1n tbe performance ot the standard yeast and mlx II made with the aame yeast wel"e similar • 1n~1oa't ing that storage 1n mix to:rm d1d not htrte a deleterious etteot on the teast, Under the ooudi.tiona maintalned in this experiment. the straight and eponse 4ouah pl"tlparatton metl»da. produoecl rolla ot acceptable quality. The UDkneaded method pro~ duoed rolla ot superior qual1tr for all mixes throughout storage, These rolls were scored s1sn1f1oantly high 1D. odor, color ot crust, oell dtatr1but1ou end cell size. They required aborter prootlns e.:nd total fermentation times. The s1mplio1ty ot this method and its shorter total term.entat ion t1ae "WOuld probablJ appeal to 'he home­ maker. so BIBLIOGRAPJIY

1. American medical association. ccepted roods and their nutritional significance. Chicago., The ssociation, 1939. 492p. 2. Anderson, J. Ansel (ed.). Enzymes and their role in wheat technology. Edited tor the American association ot cereal chemists. N.Y.; Inter­ science, 1946. 37lp, 3. Bailey• c. H .• and R. c. Sherwood. The march or hydrogen-ion concentration in bread dough. Industrial and engineering chemistry 15:624-627. 4. Baker, J. c. The structure ot. tbe gas cell in bread dough. Cereal chemistry 18:34•41. 1941. 5. Baker, J. c., B. D. Parker and M.D. Mize. The dis­ tribution or water in dough. Cereal chemistry 23:30-38. 1946. 6. Baker, J. c. and M. D. Mize. Gaa occlusion during dough mixing. Cereal ohemistrr 23:39-51. 1946. 7. Baker, J. c. and M. D. 1ze. The origin ot the gas cell in bread doughs. Cereal chemistry 18:19­ 34. 1941. 8. Brown, Elmer B. Controlled dough fermentation. Baker's digest 21:53·56,69. 1947. ' 9. Burhans, M•.E. and J'ohn Clapp. A microscopic study ot bread and dough. Cereal chemistry 19:196-216. 1942. 10. Crane, John c. ·, Harold K. Steele and Sutton Dertern. Technique for estimating the stability ot tood products: Active dry yeast. Food technology 6:220-224. 1952. 11. Dalby, Gaston. pH control in bread and cake baking. Baker's digest 23:27•28. 1949. 12. Davis, c. F. and Gisela Frenkel. A study ot the be­ havior or nonviable dry yeast in bread dough. Cereal chemistry 24:100-110. 1947. 81

Doty, J~ • and w, R. Urban. The pressuremeter in the study ot ' yeast. Cereal chemistry 17:44-54. 1940, 14. Eokstedt, G. H. Fermentation tundamentals in the production ot bread. Baker's digest 23:23-27. 194~. 15. Elion, E , The importance or gas-production and gas­ retention measurements during the fermentation ot dough. Cereal chemistry 17:573-581. 194.0. 16. Emery, H. G. and K. G. Brewster (eds.). The new cen­ tury dictionary ot the English language, vol. 1. N.Y., Appleton-Century-Croft, 1952. 1344p. 17. Frei1ioh, J. Ttme, taDperature .and humidity tactors in dough prooting. Baker's digest 23:31-34. 1949. . 18. Frey, Walter. Retrigeration ot sweet yeast doughs. Baker's digest 22:21-24. 1948. 19. Halton, P. and G. • Scott Blair. A study ot some physical properties ot tlour doughs in relation to their breadmak1ng qualities. Cereal chem­ istry 14:201-217. 1937. 20. Johnston, William R. Fermentation characteristics ot active dry and compressed yeast. N.Y., Standard brands, inc., 1951. 8p. (Paper delivered at annual meeting or national home demonstration agents' assoc., Fort Worth, Texas, NoT. 6, 1951.) 21. Kent-jones, D. • and A. J. Amos. Modern cereal chemistry. 4th ed. Liverpool, Northern, 1950. 65lp. 22. Kent-Jones, D. • and John Price. The practice and science ot bread-making. 2d ed. Liverpool, Northern; 1951. 278p. 23. Latar, Franz. Technical mioology V-II Eumycetio ter­ mentation. London, Charles Gr1ttin, 1911. 558p. 24. Laster, Robert. Prepared mixes in commercial baking. Baker's digest 22:112-114,125. 1948. \

82

25, .Lindegren, Carl c. The yeast oell•its genetics and oytoloQ. Chapter a, Saint Louis, Educational pub., 1949. pp.l-28, 26.. Lowe, Belle, Experimental cookery trom the ohem.ioal and physJ.oal standpoint. 3d ed. N~ Y,, John iley, 1943. 6llp. 27. Mcfarlane, Vernon H. Behavior or microorganisms at subfreezing temperatures III. Influence ot sucrose and hydrogen-ion concentration. Food research 6:481•492. 1941. 28. Merritt, Paul P. and Olot E. Stamberg, Active dry yeast, its characteristics and possibilities. Baker's digest 21:27-29. · 1947. 29. Miller. H., J. Edgar and A. G. o. hiteside. Ettect ot gassing rate on Tolume. Cereal chemistry 231579-565. 1946. 30. Morse, Boy E, and William B. Esselen Jr. Triphenyl­ tetrazolium chloride as a vital stain tor dried baker's yeast. Food research 14:123•130. 1949. 31. Nordsick, Frederick w. Baker's yeast-unique product. N.Y., McGraw-Hill, 1952. (Standard brands, inc., Research service dept. special tood industries report.) 32. Oyaas, J. • M. J. Johnson and W. H, Peterson. ttect ot oxyge.n on rttention ot aot1v1ty by commerci,al dried baker's yeast. Industrial and engineering obem1atry 40:280·287. 1948. 33. Pyler, E. J. The colloidal properties ot dough. Baker's digest 24:27-30. 1950. 34. Selman, Roland w. The sign1t1cance ot pH in baking. Baker•s digest 22:8-9. 1948. 35. Swanson, C. o. Tbe elastic properties ot dougbs. Baker• s digest 17: S-12. 1943. 36. Swanson, C. O. Physical properties or doughs. Minneapolis, Burgess, 1943. 257p. 83

3'1 ,. Swanson, C.., 0.• and A~ 0.•. Andrews.- Ettects ot papain, yeast, water, cysteine, and glutatheone on glu­ ten dispersion or on disintegration as indicated by gluten reooTery and by mixogram patterns.• Cereal chemistry 22: 134,..149.. 1945. 38. Swanson, Emery C. and c. o. Swanson.- Gas production and gas retention ot dough as attected by type or tlour, baking tormula and amount ot mixing. Cereal chemistry 22:432-439. 1946. 39. Swanson, Emery c. and c. o. Swanson. odttication ot the gas production and gas retention properties ot dough by some surface active reducing and oxidizing agents. Cereal chemistry 23:590-600. 1946. 40. Sweetman, Marion Deyoe. Food preparation. 2d ed. N.Y., John Wiley, 193'1. 449p. 41. Sumner, James B. and G. Fred Somers. Chemistry and methods ot enzymes. N.Y., Academic, 1943. 365p. 42. Thaysen, A. c. and L. D. Galloway. The microbiology ot ste.roh and sugars. London, Oxford u., 1930. 336p. 43. alden, o. c. and R. K. Larmour. Studies on experi­ mental baking tests IV Combined ettects or yeast, salt and sugar on gassing rates. Cereal chem­ istry 25:30-40. 1948. 44. Zaehringer, Mary V• ., Helen L. Me.ytield and Lura Mae Odland. The ettect ot certain variations 1n tat, yeast and liquid on the trozen storage ot yeast doughs. Food research 16:353-359. 1951. 84

,.···-'t'o 85

TABLE I AYerage Carbon-Dioxide Production, pH Values and Ratio ot AotiYe to Inactive Yeast Cella tor Eaoh Kix at o, 5, and 10 We•ka Storase

Cell Count Mix Storage Ratio ot AotiYe pH C02 to InaotiYe Cella Production Mix I 0 3.38 6.23 98.2 5 1,60 6.Sl 45.7 10 0.97 6.47 46.3

Mix II 0 6.21 6.27 133.0 5 1.38 6.29 81.2 10 2.75 6.42 57.8

Mix III 0 1.35 6.40 80.9 5 2.78 6.41 66.5 10 7.77 6.39 92.7 TABLE II Average Prooting Times and Fermentatioa T1DJ.es4 tor Doughs at O, 5, and 10 Weeks Storage

______~- Storage Method o Weeks 5 Wiilta- ~-~-~------~O~Weeks rermentation PrOOfing - J'ermeritat ion~Pro-otlng- u"l'ermin tat-ton--Proofing T~ T~ T~ T~ T~ T~ Standard 125 66 126 66 135 6'1 Jlix I Straight 144 '10 202 10$ 228 113 Sponge 184 50 235 '14 261 '13 Unkneaded 156 68 li5 '13 18'7 '10 - Standard 125 62 142 '14 150 81 Mix II Straight 156 81 142 '10 168 82 Sponge 212 61 190 65 183 66 lJnkneaded 138 55 138 56 165 '12

Standard 1$0 '12 160 81 155 '15 Mix III Straight 128 68 166 92 1'14 89 Sponge 1'16 53 211 10'1 216 '11 Unlmeaded 122 55 154 51 155 '15

'All Ttmes in Minutes.

(l) 0 TABLE III Bxpans1b111ty ot Doughs as lnd1eated by Volume Attained an4 'lime Required tor Jlu1mum Expansion

- ~-Storagt- - - -·- -·. --­ t -~ . ___ -- -- ~ - - · - ·~------·-­ Jlethod 0 Weeks 5 Weeks -----~10 Weeii---~. - Volume · !'lie Vc:Jlume Tlii ··Volume · TiDli o.o llln. oo lf1n. oo JUn.

Standard uo 120 112 150 ll' 180

141x I Straight l1Z 210 93 150 85 150 ~-. Sponge 119 210 91 120 89 150 Unkneaded .ll& 150 8'1 120 lOS 150

Stan4ar4 125 180 12.2 180 107 150 Jllx li Straight 100 150 uo 210 107 180 Sponp t1 90 113 180 lO.S 150 Unkneaded ;3 120 97 120 107 180

Standard 130 120 114 180 104 150 Mix III Straight 125 210 116 210 112 150 Sponge 10'1 150 102 150 112 120 Unlmeade4 95 120 ll5 150 122 180

CD ~ TABLE IV ATerage pH Values at Each Storage Period ot Standard end lUx Doughs When Piret Prepared, After Per,mentation, and Atter Proofing

Stora&! 0 'lee:is 5 l'eeke IO Weeks Method Uter Ifter Attar Itter Itter After First J'eraan• Proot­ 11rat :re:rmen­ Proot· Jirat '•:rm•n­ Proot­ Mixed tatton lng Jlixed tat1on 1y Mi:zed tatlon 1ng

Standard 6.2'1 5.97 5.'19 &.11 5.86 5.74 5.9'1 5.'13 5.6~ lUx I Straight 6.22 6.02 6.01 6.23 5.88 5.87 6.21 5.98 5.75 Sponge S.99 6.07 5.8'1 5.96 5.80 5.70 5.92 5.'16 5.63 Unkneaded 6.38 5.89 5.97 6.26 5.89 5.66 6.11 5.87 5.61

Standard 6.15 5.91 5.84: 6.15 5.95 5.'18 6.02 5.76 5.'10 Mix II Straight 6.23 6.0'1 5.9-l 6.26 5.8'1 5.'11 6.23 5.85 5.'17 Sponge 6.06 5.91 5.82 5.98 5.84: 5.74. 5.96 5.76 5.69 Unkneaded 6.21 5.91 5.80 6.31 5.91 5.62 6.14: 5.88 5.77

Standard 6.U 6.03 5.84 6.21 5.90 5.84: 6.22 5.77 5.71 Mix III Straight 6.39 5.95 5.77 6.31 6.00 5.73 6.25 5.77 5.64. Sponge 5.96 5.83 5.. 7-l 5.95 5.70 5.61 5.80 5.70 5.'12 Unlmeaded 6.42 5.7'1 5.72 6.06 5.89 5.54: 6.20 5.76 5.82

i TABLE V Anal1•1• ot Variance ot Soores tor Roll Palatability

Jlean sgnarea Souroe ot Color Cell Crwab dolor Variance D•sr•••J'reedom ot Dlstrl- Cell Cruab Spring- ot Oclor Crust butlon Size Jloisture ineaa Crumb FlaTer Replica­ 'tion (B) 2 .99 .eo -­ -­ - ...~ .61 1.96 Method (If) - 8 13.63* 2.. 65* 19.04* 19.2881* 11.2896* 38.935'1* '1.81* 9.80

llix (A) 2 12.9'1* .1$ 25.48 43.1991* 13.2608* 23.6358* 20.J~9 25.50*

Storage (S) 2 3.52* 3.95* .49 .0602 3.2145 4.35M ~53 5.21* JIXA 6 1.82 .39 3.09 5.9686 1.'1094 4._0391 2.55 3.60*

JlxS 6 . ·65 .72 .26 .'1433 .6137 .9542­ ~62 .96 AxS 4 1.06 1.81 . 8.82* 11.0'11.8 3.0641 4:.8048 5.14* 2.1.9 JIXAXS 1.2 .52 .53 2.4:9 2.4308 .6'100 1..9581 1.11 .'1'1 Error '10 .83 .90 2.88 4.5222 2.1936 2.9'1'11 1..'18 1.21 Total 10'1 -­ - .... -· -­ --· -­ - *Signltioant at 5~ leTel. .,CD TABLE VI

ATerage Soorea ~or Rolls Made From Rolla Made by Three Methods From Freshly Prepared lUx

Oharaoter­ M1x I Mix II llix III iatio Un- Un­ Un- Straight Sponge kneaded Stra~t Sponge kneaded Straight Spon~ kneaded

Odor 4:.66 -i.28 4.55 4.05 3.86 4:.28 4:~94 4._55 4.88 Color ot Cruet 4:.'12 4.88 5.50 4.~0 4.'12 4.66 4.'12 4:.88 5 •.16 Color ot Crumb 4.'12 4.66 5.16 4.05 3.66 .4.22 5.50 5~22 5.22 ' Cell Diatributton 4.55 4-.94 5.'1'1 4.11 3.4:4 3.91 5.61 5.61 5 •.50 Cell Size 4.55 4.94 5.60 3.'12 3.11 3.50 5.66 5.22 5.55 CrUIIlb Moiatneaa 4.38 4.44 4.'12 4.29 3.61 4.00 4.88 4.66 ..._'1'1 -crumb Spr1ng1neaa 4:.28 3.91 4.55 3.91 2.83 4.05 5.28 4.22 4,.94 llaTor 4.61 4.28 4.9-i 4.11 3.55 ••05 5.11 5.05 4._88

.a 0 TABLE VII

A•erase scores ~or Rolls Made by Three Vetho4a From Mixes Stored 5 Weeks

Character- K1z I Kix II llix III istic Un­ Un- UD- Straig!lt Sponge kneaded Straight Sponse kneaded Straight SpoaS! kneaded Odor 4:.22 4.44 4.50 •• 28 4.'17 5.11 4.50 5.28 '·"' L Oo1or o~ Crust "·" ·4.50 4.66 4.77 5.00 ~.' 88. 4.61 4.50 4.94 Color o~ Crlab 4.11 4.50 4.50 4.'1'1 4.66 5.22 5.28 4.aa 5.44 Cell Distribution 4.28 ·· 4.00 4.44 4.61 4.'38 5.16 5.28 4,.'17 6.16 ' Cell Size 4.11 4.11 4.55 4.44 4.38 4.'17 4.94 4.:!~0 5.94 Crumb Moistness 4.16 4.11 4.~3 4.'12 4.55 4.88 5.11 4.66 5.22 Cruab Springiness 3.66 3.83 3.72 4.61 3.72 ••61 5.22 4.05 5.«

:rla~r 4.33 4.22 4.55 •.83 ' 4.11 4.88 5.22 4.83 5.39

...G . TABLE VIII

ATerage S~~· tor Bolla Made b7 Three Me~hoda From Mixes S~ored 10 Weeks

Charao~er- llix I K1X II Mix III ist1o Un- bn- un­ Stra1gb.~ Spoage kneaded ~S~I-_ai_gbt S_pQD.ge_ kn~a~~4, _J)_~alsM_~~nge kne~aded Odor 4 .• 77 4.11 5.39 "·'" · 4.S3 4.61 5 .. 39 4.83 5... Color ot Cruat 5.28 5.11 5.22 4.83 5.ll 5.34 5.0 . 4.'17 5.05 Color ot CrllBlb ••77 4.16 ~.22 4..38 4.33 ••72 5.16 ••88 .5.61 Cell Distribution 5.00 ·4.22 5.39 4.50 4.28 5.06 4..94 4.88 5.61

Cell Size 4.61 4..0 5.22 3.86 4.05 4.50 5.0 ' 4.61 5.83 Crumb :oiatneaa 4.61 4.05 6.00 •• 55 4.28 4.61 5.22 4.88 5.·34 Crab Springiness 4.61 3.83 5.39 4.11 3.9ll 4.66 5.34~ 4.28 5.16 JlaTor 4 •.72 4.28 5... 4..33 4.U· 4.77 5.66 5.34- 5.61

co t'O .93 'l'.ABLE IX Analysis ot Varianoe ot Boll Crosa-Seot1on Areas

Degrees Souroe ot Var1anoe l"ree4oa Kean Squares Replication (R) 2 21,'185.65

Method (II) 3 89,735.70• )fix (A) a 63,206.55 Storage (S) 2 1,'760.20 MXA 6 13,78'7.6'7* llxS 6 4,967. 22 AXS 4 3'7,54'7.95* MxAxS 12 4,825.49

R x Trea'blent '10 3,121.72* Error 324 • 8'7.35 Total 431

*S1gn1t1oant at 5~ le'fel. TABLE X ATerage Croaa-Seotion Areas ot Standard Bolla and Bolls Kade b1 Three Methods trom Mixes Stored 0, 5, and 10 Weeks

Method storaee 0 Weeks 5 Wee • lO leeks Standard 100 587 578 Mix 1 Straight 60~ 526 494. Sponge &'10 512 494 Unkneade4 612 560 582

Standard 599 600 59'1 Mix II Stra1Sht 621 580 541 Sponge 550 555 5~5 Unlmeaded 604 602 593

Standard 609 598 586 Mix III Straight 506 631 600 Sponge 484 539 580 Unkneaded 558 609 650 a. Flour and water dough. b. All ingredients plus Yeast I.

o. All ingredients plus Yeast II. d. All ingredients plus Yeast III.

Figure I. Effect of Different Yeasts on Mixogram Patterns. 96

a. Dough made with Mix I.

b. Dough made with Mix II.

o. Dough made with Mix III.

Figure II. Effect of Freshly Prepared Mixes on Mixogram Patterns. 97

a. Dough made with Mix I.

b. Dough made with Mix II.

c. with Mix III.

Figure III. Effect of Mixes on Mixogram Patterns After 10 Weeks of Storage.