Food Structure

Volume 12 Number 4 Article 10

1993

Baking Properties and Microstructure of Yeast-Raised Breads Containing Wheat Bran: Carrageenan Blends or Laminates

P. R. Belisle

B. A. Rasco

K. Siffring

B. Bruinsma

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Recommended Citation Belisle, P. R.; Rasco, B. A.; Siffring, K.; and Bruinsma, B. (1993) "Baking Properties and Microstructure of Yeast-Raised Breads Containing Wheat Bran: Carrageenan Blends or Laminates," Food Structure: Vol. 12 : No. 4 , Article 10. Available at: https://digitalcommons.usu.edu/foodmicrostructure/vol12/iss4/10

This Article is brought to you for free and open access by the Western Dairy Center at DigitalCommons@USU. It has been accepted for inclusion in Food Structure by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. FOOD STRUCTURE, Vol. 12 (1993), pp. 489-496 1046-705X/93S5.00+ .00 Scanning Mic roscopy International, Chicago (AMF O' Hare) , IL 60666 US A

BAKI G I'ROPERTIES A D MICROSTRUCTURE OF YEAST-RAISED BREADS CO TAINING WHEAT BRA :CARRAGEE AN BLE DS OR LAMINATES

1 3 P.R. Belisle , B.A. Rasco2, K. Siffring3 and B. Bruinsma

1Ski pper's In c .. 14450 N.E. 29th Place, Suite 200, Bell evue, WA 98007 21n stitute fo r Food Science and Tec hnol ogy, HF- 10 , Universi ty of Washi ngton , Seattle, WA 98 195 3The Rom an Meal Co., P.O. Box 11126, Tacoma, WA 9841 1-0126

Abstract Introduction

Breads prepared using a commercial prototype The purpose of baking dough is to present cereal sponge-and·dough formulation with no added gluten and flours in an attractive, palatable and digestible form. In containing white wheat bran:carrageenan blends or white commercial baking, various high fiber ingredients have wheat bran:carragcenan laminates (I 0% by weight nour been added to bread to increase the fiber con tent; how­ replace ment) had acceptable loaf volumes and crumb ever, ad ding increased amounts of fiber such as wheat grain scores. Doughs con taining white wheat bran:car­ b ran to bread can lead to a significant reducti on in loaf ragccnan blends had a hi gher water absorption and long­ volume, poor color, te xture, mouthfeel, and navor. In· er mi xing time than doughs con taining wheat bran: carra­ creasing the amoun t of fiber that ca n be incorporated gecnan laminates wi th th e sa me quantity of ca rrageenan . i nto a loaf of bread would hav e sig nifica nt nutritional The addi tion of carrageenan to doughs resu lted in a benefits. Whea t bran and the use of fibrous mate rial s in higher wate r absorpti on va lue compared to th e dough s breads ha s been rev iewed by Pomeranz. et of. ( 1977) who contai ning wheat bran only. Breads made wi th wheat found th at adding hi gh leve l s of fiber suc h as wheat bran bran:carragccnan ( 10 % nou r repl acement ) had enh anced l ed to gluten dilution and caused significa nt reductions loaf volume and improved crumb gra in sco re com pared in loaf volume. to breads with comparable quantities of wheat bran. Scanni ng electron micrographs of the breads con ta ining As early as 1968 , Glabe and Jenso n determined 10% flour replacement of the wheat bran :carrageenan t hat adding carrageenan to breads made by continuous blends or laminates may indicate that perforations of the mixing resulted in breads with acceptable loaf volumes. gluten and gelatinized starch matrix in the wheat bran I n breads, hydrocolloids suc h as carrageenan bind water bread s containing the ca rrageenan may be more uniform, :affecting the rheological properties of the dough and and the perforations sma ller than in breads containing thus the finished product quality of the baked bread untreated wheat bran at the same flour replacement (Bruemmer. 1977). level. Scanning electron microscopy (SE M) allows food scient ists to study structural features of food products Key Words: High fiber breads, wheat bran , ca rra­ (Aranyi and Hawrylewicz, 1969; Hall and Sa yre, 1969; geenan in breads, wheat bran:ca rrageenan laminates. Boyde and Wood , 1969). Due to its large depth of fie ld and magnification range , SEM provides a means for c haracteri zing physical properties and te xtural attributes of food ingredients in a fo rmulated product. Although SEM has been used to study the microstru cture of nour Paper received August 8, 1993 doughs and the changes occurring in the dough during M anuscript received November 18, 1993 mixing an d dough development , there have been few Direct inquiries to B.A . Rasco SEM studies of bread structure after baking (Khoo eta/. Telephone number: 206 685 1203 1975; Chabot, 1979; Pomeranz and Meyer, 1984; FAX number: 206 543 1417 Bechtel. 1985; Freeman and Shelton, 199 1). The prima­ ry objective of th is re search was to study the baking properties of yeast raised bread containing wheat bran: carrageenan blends, or wheat bran:carrageenan laminates and to examine the structure of the breads containing these ingredients by SEM .

489 P. R. Beli sle, B. A. Rasco. K. Siffring and B. Bruinsma

Table I . Sponge-and-dough formulationa Table J . Fiber ingredients and flou r replacement levels Ingredient weight in grams tested (x) (ND: not determined).

Sponge In gredient Flour replacement level 5 % 10% 20% Bread flour 70.0 Yeast, compressed 2.5 W heat bra n Water 47. 0 (variable) Fiber ingredient (see Table 21 Wheat bran:carrageenan blends (w/ w) 95:5 X ND ND Dough 90: 10 ND Bread nour 30.0 Wheat bran:carrageenan la minates (w/ w) Salt 2.0 Sugar 6.0 100:0 X Shortening 3.0 95.5:0.5 ND ND Potassium bromate 2.0 pg 99:1 Ascorbate (as ascorbic acid) 10.0 pg 98:2 Yeast, compressed 2.75 95:5 Water -16.0' 90:10

•For a single loaf. Procedure: Mix sponge ingredient 10 % carrageenan). The aqueous suspensions were dried and ferment 3 hours (80"F). Optimally mix sponge and usi ng an atmospheric double drum dryer (model ALC-4, dough ingredients, proof to an average proof time of 55 Blawknox, Buffalo, NY) operated at a steam pressure of minutes based on proof time of flour control , bake at 275 to 300 kPa (40.4 -44 .3 psi) a nd a speed of approxi­ 425 ° F fo r 17 minutes in rotary convection oven. Meas­ mately 2.5 rpm . The drums were spaced 0 .2 mm apart. ure loaf vo lume immediately after baking by rapeseed This drying treatment allowed th e wheat bran an d carra­ displacement method. geenan to be evenly dispersed. ·water as required for o ptima l dough processing. Commercial protot y pe ba king trials Duplicate laboratory pup loaves ( I 00 g n our/14 % moistu re basis) were prepared us in g a sponge-and -dough Table 2. Fiber Replacement Levelsa process patterned after commercial baking spcci fications (Roman Meal Co., Tacoma, WA (Table 1)] . For control Ingredient Replacement levels (g) doughs (no added fiber ingredient), 70.0 g o f white 0 % 5% 10 % 20% bread nour [14 % moisture basis, (All- Montana Flour, Centennial Mill/ ADM Milling Co., Portland, O R) con­ Flour• 100.0 95.0 90.0 80.0 taining 12 % protein (1 4 % moisture basis) was used. No F iber Ingredient 0.0 5.0 10.0 20.0 gluten was added to this formulation . To the flou r, 2.5 g compressed yeast, and 47 ml water was added, and 8 Level of fiber ingredient added in place of flour to a sponge formed by mixing for I minute (Model 100-200 formu lation in Table 1. b14 % moisture basis. A, 100-200 g mixer, National Mgf. Co., Lincoln , NE). Sponges we re fermented for 3 hou rs at 80°F (26.7°C) in Materials and Methods a controlled temperature cabinet (Despatch Industri es, In c., Minneapolis, MN). After fermentation , 30 g nour Whea t bran :c~trrage c n a n blends at 14 % moisture. 2.75 g compressed yeast, 6 g granu­ White wheat bran (Fisher Mills, Harbor Islan d , lated sugar, 2 g salt , 3 g hydrogenated vegetable short­ WA) was mi xed with carrageenan (Sati gum -CD , Sanofi enin g , 20 ppm potassium bromate, I 00 ppm ascorbate Bi o Ingredients, Germantown, WI) as a dry blend at (as ascorbic acid), a nd water as required for optimal levels of 95:5 (weight/ weight , w/ w) or 90: 10 (w/ w) dough formation, were added. The doughs were mixed prior to its incorporation as a fiber ingredient into unti l optimal development was reached . Dough tempera­ doughs. tures after mixing ranged from 77 ° F to 80° F (25 °C to \\'heat bran:carrageena n laminates 26. 7 "C). Following mixing, th e doughs were allowed to The laminated fiber ingredients were produced by rest for 10 minutes at room temperature at 77°F (25 °C), coating white wheat bran (Fisher Mills, Harbor Island, scaled , a ll owed to rest for 10 minutes at room tempera­ WA) with carrageenan (Satigum-CD, Sanofi Bio Ingredi­ ture, molded , and then placed into baking pans and ents, Germantown, WI). Laminates were made by mix ­ proofed 55 minutes in a humidified cabinet a t ll2° F (44.4 ° C). Breads were baked in a r01ary oven a t 425°F ing 400 g whi te wheat bran with varyi ng levels of carra­ (218"C) fo r 17 minutes. geenan (0. 0.5, I, 2 , 5 or 10% by weight) and then add­ ing water (1,000 ml for mixtures containing 0, 0.5 or Wheat bran or wheat bran: carrageenan b lends or I % carrageenan ; 1.200 ml fo r those containing 2, 5 or laminates were added to th e formu lati on in Table I (Table 2) with appropriate adjustme nt s made to t he water

490 High fiber bread

Table 4 . Mixing properties of flour doughs containing wheat bran and wheat bran:carrageenan fiber ingredients. 1 Product Farinograph Mixing Tests Sub level Water abs. Dev. Time Opl. mix. time Water abs. (%) (%) (min.) (min.) (%)

Flour (Contro1)2 ND 59 9.0 2.5±0.2' 66.0±0.5'b Wheat Bran 3 5 ND ND 2.4±0.2b 67.5±0.8' 10 64 14 .0 2.6±0. 1' 67 .5±0.6. 20 70 16 .5 3.8±0.3 71.0± 1.3'b Wheat bran :carragccnan blend 95 :5 (w/ w)3 5 ND ND 4.0±0.0' 67.0± 1.4'b 90: 10 (w/ w) 10 67.5 33.0 4.0±0.7'bc 68.0±0.0'b 20 74.5 50.0 5.5 ±0.8'•' 75.5±0.5'b Wheat bran:carrageenan laminate 100:0 (w/w) 5 D ND 3.1±0.5 68.0±0.6'b 10 63 11.5 3.4±0.1 68.o±o.oa• 20 69 12 .0 4.5±0.3'bc 73.0±2.3'b 99.5:0 .5 5 ND ND 3.0±0.6 67.0±0. 7'. 99: 1 5 ND ND 2.6±0.1 67.0±0.8'b 10 ND ND 3.5±0.1 68 .0±0.5'b 20 ND ND 4.4±0. labc 73.0±2.6'b 67 .0±0.6'b 98:2 5 ND ND 3.0±0.5 10 ND ND 3.8±0.3'b 70.0±0.5'. 20 ND ND 4.6±0.4abc 74.0±2.5'b 95:5 5 ND ND 3.6±0.3 67.0± u•• 10 64 13 .0 4.6±0.3'bc 70.0±0.5'b 20 72 19 .5 5.4±0.6'bc 73.5± 1.9'b 66.0± I. 7'b 90: 10 5 ND ND 4.2±0.5'bc 10 65 20.5 5.7+ 1.4abc 70.0±0.5'b 20 72.5 28.0 6.o±o.6'•' 70.0±0.8'b

D - not determined. 1Water absorption and development times for farinograms are single values. 2Sample average for flour controls are from four loaves from two baking trials (n = 8) .

3For doughs con taining fiber ingredients1 two replicate loaves from two baking trials were analyzed (n = 4) . 11 -cValues within a single column for the breads containing the wheat bran blends or laminates were significantly different (p < 0 .05) from the control (a) , wheat bran (5 %) (b), or wheat bran (10%) using one-way analysis of variance and the Fisher primary least sq uare difference (PLSD) te st. ------ad dition at the "dough" stage for optimal mixin g. Fo r at 30-60 rn Torr, -50 to -55 °C (Frceze mobi le VI, Virti s, each level of fiber tested , dup licate loaves of bread were Inc .. Gardiner, NY)] . Surfaces were exposed for samp l­ prepared in two sepa rate trials. The fiber ingredient and ing by removing a thin layer approximately 1.0 mm replacement levels used in the breads are given in Table thick. From the remaining bread. small pieces no 3. Immediately after baking, loaf volume of each loaf greater than 4 mm in height and 10 mm in length were was measured by the rapeseed displacement method and cut and mounted on SEM specimen holders with colloid­ subjective measurements of crumb grain and texture al silver paste (#16032, Ted Pella Inc ., Redding, CA) to were made (Rasco eta/. 1991). Water absorption values increase conductivity. The mounted samples were sput­ for the wheat nour doughs were conducted using the ter coated with gold-palladium (15 nm layer) for a total constant nour weight-variable dough weight method of 4 minutes (2 minutes on top su rface, I minute each of (AACC ( 1986) method 54-2 1] . 2 side view surfaces) at 10 rnA in a Hummer V Sputter Scann ing elect ron microscopy Coater (Model HUV , Technics EMS Inc ., Springfield, VA). Once prepared, the specimens were examined with Breads were sliced to a th ickness of 0.5 inch a JEOL scann ing electron microscope (Model JSM -840 (1.25 em) within I hour after baking and frozen at -20 ' F A JEOL Ltd. , Tokyo) operated at an accelerating voltage (·28.9' C). The frozen slices were lyophilized (48 hours

491 P. R. Belisle, B. A. Ra sco. K. Siffring and B. Bruinsma

Table S . Baking Parameters for Breads Containing Wheat Bran and Wheat Bran :Carragcenan Fiber ln grcd1erts. Product Sub level(%) Dough wl. (g) Loaf wt. (g) Loaf vol. (mm3) Crumb Grain 1

Control2 0 174 . 1 ± 1.5 147 .9 ± 2.2 1,040 ± 53' Wheat Bran3 5 174 .7 ± 1.6 147 .7 ± 2.6 989 ± 29b s 10 176.0 ± 0.5 150 .0 ± 0.7 998 ± 24' s 20 179.4 ± 1.6 154.3 ± 0.9 849 ± 24a.b.c s Wheat Bran:Carrageenan Blends3 95 :5 (w/w) 5 174.2 ± 0.2 146.0 ± 0.9 1, 145 ± 28a,b,c s 90: 10 (w/ w) 10 174 .5 ± 0.9 148 .2 ± 1.1 1,092 ± 1911 s 20 175.6 ± 3.0 149 .5 ± 1.3 9 13 ± 49' Q-S Wheat Bran:Carrageenan Laminates3 100:0 (w/ w) 5 176.0± 1.5 149.6 ± 2.2 982 ± 28 s 10 175 .9 ± 1.1 148 .9 ± 2.5 929 ± 19' s 20 180.7 ± 3.4 155 .5 ± 1.4 781 ± 3011,b.c Q-S 99.5:0.5 (w/w) 175 .8 ± 1.4 148.1 ± 2.3 984 ± II s 99: 1 (w/ w) 5 174 . 1 ± 1.5 148.5 ± 1.2 1.000 ± 41 s 10 176.0 ± 0.5 148 .6 ± 1.3 976 ± 21 s 20 181.2 ± 2.6 154 .6 ± 1.6 851 ± 51 '·"·' Q-S 98:2 (w/w) 5 175 .0 ± 1.4 148.8 ± 0.7 1,034 ± 30 s 10 177.4 ± 0.6 151.5 ± 1.1 1,028 ± 9 20 181. 1 ± 2.1 154 .8 ± 0.8 88 1 ± 43'···' Q-S 95:5 (w/ w) 5 174.9 ± 1.1 149.9 ± 1. 3 1, 085 ± 18" s 10 177.0 ± 0.8 150 .6 ± 1. 4 1, 060 ± 23 s 20 179. 1 ± I . I 153.0 ± 0.7 868 ± 44'·"·' Q-S 90:10 (w /w) 5 174 .9 ± 0.8 147.6 ± 1.9 1,259 ± 40'···' s 10 176.3 ± 1. 3 149.5 ± 1.3 1,090 ± 23b s 20 176.4 ± 0.8 151.8 ± 0.7 839 ± 21 '···' Q-S

1Crumb grain rated using a three-point scale with S = satisfactory, and Q = questionable (Rasco eta/. 199 1). 2 Values for control (no added fiber ingredient) were from four baking trials with two loaves per trial (n = 8). 3Values for fiber containing breads were from two baking trials with two loaves per trial (n = 4) . a-c vatues within a single column for the breads containing the wheat bran blends or laminates were significantly different (p < 0.05) from the control (a). wheat bran (5%) (b) , or wheat bran (10%) using one-way analysis of variance and the Fisher PLSO test.

of 3.5 kV . Specimens were photographed on posi tive/ hig he r water absorp tion va lues (p < 0.05) than the negative 4" x 5" instant sheet fi lm (Polaroid 55 Profes­ doughs cont ai ning no added fiber (cont rol) or the un­ sional, Polaroid Corp ., Ca mbridge, MA). treated wheat bran a t th e 5% f1 our repl acement level. Mix ti mes for wheat bran:carrageenan bl end s ( l O% or Results 20 % nour replaceme nt level) we re hig her (p < 0.05) than for the control o r breads conta in ing wheat at eithe r Table 4 sum mari zes water absorption values, de­ a 5% or 10% n our replacement level. Mix times for velopment times and optimal mix times for doughs con­ doughs containi ng the wheat bran :carrageenan laminates taining from 5-20% of the various wheat bran based (20% nour replacement level) we re also higher (p < fiber ing redients. Development times were longer fo r 0.05) than the mix times fo r the control or doughs the wheat bran:carrageenan blends than fo r the wheat containing wheat bran at the 5% or 10% flour replace­ bran:carrageenan laminates containing ei ther the same ment level. However, mix times for the doughs contain­ level of carrageenan , or when the fiber ingredients was ing the wheat bran:carrageenan laminates at the 10% added to the bread at the same flour repl acement level. flou r replacement level were only significantly different Addition of carrageenan Jed to higher water absorption from the control (p < 0.05) at higher carrageenan con­ valu es fo r the doughs relative to doughs contai ning centrations (Table 4). wheat bran at th e same nour replacement levels. The Table 5 shows the results of the bakin g tests dough cont aining wheat bra n blends and la minates had includin g loaf volume an d c ru mb grai n scores. Addition

492 High fiber bread

Figure I . Scanning electron micrographs of breads; note pe r foration of gluten- starch matrix (arrows). a) Control, no added fiber ingredients. b) W heat bran, 10% flour replacement level. c) Wh eat bran :carrageenan blend (90: 10 w/ w) , 10 % flour replacement level. d) wh eat bran :carrageenan laminate (90: 10 w/ w) , 10% nour replacement level. Bars = 100 I'm.

of carrageenan either as part of a white wheat blend , or Disc uss ion as a laminate , resulted in breads which had greater loaf vo lu mes than bread s containing com parab le levels of A predicted advan tage for th e wheat bran :ca rra­ wheat bran but no carrageenan. Breads made with 5- geenan fiber ingredien ts was that such ingred ient s would 10 % of th e whea t bran :ca rragcenan laminates (98 :2, inco rporate th e beneficial propert ies of both a so luble 95 :5 or 90: 10 w/ w) had loaf volumes which were similar and insoluble fiber ingredient into a single material. to or greater than the cont rol (no fiber ingredient). The The "lamination" process in volved heat in g the whea l loaf volumes of the breads containing 5-10% of the bran and carrageenan in an aqueous med ium permitting following laminates (98 :2. 95:5, or 90: 10 w/ w) were 3 the hydration of the gum along with various components to 25% higher than for breads containi ng either 5% or in the wheat bran. A large number of lhe sta rch gran­ 10 % white wheat bran (Table 5) . ules contained in the bran were damaged during the lam ­ Structural features of freeze-dried bread ination process with the laminate containing a significant specimens examined by SEM are shown in Figure 1. amount of gelatinized starch. Damaged srarch plays an White wheat bran or white wheat bran:carrageenan important role in water absorption by doughs (Shelton blends or laminates were added at a 10% flour replace­ and D'Appolonia, 1985) . I t must be present at optimal ment level. Breads co ntaining white wheat bran:carra­ levels relative to the concentration of a and {J amylase geenan blend or laminate (90: 10 w/ w) (Figures l c and to produce desirable characteristics during bread-making I d) appeared to have a more uniform distribution of per­ such as adequa te gas production , baking absorption an d forations . and sma ller perforations of the gluten-starch product ion of browning reaction products during baking. matrix than the wheat bran control (Figure I b). Subjecting bran to a lamination process such as th e one

493 P. R. Beli sle, B. A . Rasco, K . Siffring and B. Bruinsma described here may sign ificantly redu ce development crumb structure composed of a well -developed network times and may be an advantage in straight dough systems of thin protein sheet s and most probably swol l en and ex­ (Table 4). For th e 20% substi tution level , th e develop­ panded sta rch granules supporti ng gluten structure ment time for the dough containing th e wheat bran which (Pomeranz and Meyer, 1984). When bran was added to had been hydrated and drum dried (whea t bran:carra­ the doughs at a 10 % flour replacement level, perfora­ geenan laminate 100:0] was significantl y lower th an for tions in th e gluten-sta rch matrix appeared to be larger the dough containing untrea ted wheat bran. The optimal and less uniform. Adding wheat bran as a component of mix times for the dough s containing the laminates were a ca rrageenan blend or laminate ( Figs. l c and ld) did higher than for those containing untreated wheat bran, not appear to have as gieat an effect on th e appearance suggesting that any advantage of a more rapid initial of th e gluten-starch matrix as did add ition of wheat bran hydration of the fiber ingredient would be lost in a alone. sponge-and dough process. In the control breads (no added fiber ingredient), Conclusions dough development was as expected (Table 4). How­ ever, in the doughs containing the carrageenan blends, The addition of ca rrageenan at 2-10% of a wheat the ca rragee nan formed doughs with a high lubricity bran based blend or laminate increased loaf volumes rel­ which made it difficult to monitor dough development. ative to bread which contained the same quantity of Optimal mix times wa s longer for the doughs containing wheat bran. Water absorption and mix times were high­ the ca rrageenan blend or th e carrageenan laminates. er for the dough s which con tain ed wheat bran:carra­ Gums ca n fun ction to entrap whea t bran and bind larger geenan blends or laminates than those co ntaining only aggregates of wheat bran together (Shaw and Sharma, wheat bran. Scanning electron micrographs of th e 1989). A s the concentration of either the wheat bran: breads containing 10 % flour replacemen t of the wheat carrageenan blend or laminate increased in the dough bran:carrageenan blends or laminates may indicate that formulation , the elasticity of the dough during mixing th ese treated fiber ingredients may have a less detrimen­ increased dramatically. The changes in mixing proper­ tal impact on the integrity of the gluten-starch matrix ties of the dough s containing the carrageenan blends than wheat bran at the sa me flour replacement level as could po se problems to commercial bakers by increas ing indicated by a more uniform distribution of small per­ mix time and making dough handling more difficult. forations in the matri x. Without th e addition of ca rrageena n, the deve l ­ opment time for th e wheat bran containing doughs was Acknowledgements longer than for tho se containing the hydrated drum-dried wheat bran (whea t bran :carrageenan laminate 100:0 The authors would like to thank Dr. Barbara w / w). Dou gh de velopm ent times were higher for the Reine, Department of Botany for instruction on SEM wheat bran: ca rragccnan blends than for th e correspond ­ use. This research was sup ported in part by the Egtvedt i ng laminate. These resu lts sugges t that the hydration Food Re sea rch Fund, Institute for Food Science and and heating of th e bran during the lamination process Tec hnology, Universi ty of Washington. ma y have gelatinized a portion of th e starc h in the wheat bran , and al so hydrated bran protein and other wheat References bran component s allowing for easier hydration of the fiber product during fermentation and mixing (Table 4) . AACC: American As sociation of Ce real Chem­ Development times for all doughs containing ca rra­ ists. ( 1986). Method# 54-2 1. Analytical Methods. The geenan increased proportionately as the leve l of carra­ Am. A ssoc. Cereal Chern. St. Paul , MN. geenan increased . Aran yi C, Hawrylewi cz EJ. (1969) . Application Baking and farinogram absorption values may of scanning electron microsco py to cereal spec imens. have differed due to va ri ations in the rate of hydration Cereal Sci. Today 14 : 230-233,253. of the fiber ingredients during the three hour fermenta­ Bechtel DB. ( 1985). The microstructure of wheat: tion period utilized in the sponge-and-dough baking Its conversion into bread. Food Microstruct. 4: 125- 133. process. Hydration of bran fiber is relatively slow Boyde A, Wood C. (1969). Preparation of animal (Rasco eta/., 1990). Crumb grain scores for all of the tissues fo r surface-scanning electron microscopy. J. fiber containing bread s were satisfactory at nour subs ti­ Mi crosc. 90: 22 1-249. tlllion levels of five or ten percent. However , the mi x­ Bruemmer JM. (1977). Hydrocolloids for bread ing properties of doughs prepared with either the wheat manufacture. Getreide, Mehl -und-Brot. 31 ( 11 ): 296-299. bran :ca rragee nan blend or the wheat bran :carrageenan Chabot JF. (1979) . Preparation of food science laminates may make these materials difficult to handle in sa mples fo r SEM . Sc anning Elec tron Microsc. 1979;Jil: a commercial operation . 279-286,298. Multiple ob se rvation of scan ning electron micro­ Freeman TP, Shelton DR. (1991). Mi crostructure graphs revea led differences between the crumb structure of wheat starch. Food Tech. 45: 162- 168. of the control and the fiber containing breads. The con­ Glabe E, Jenson E. (1968). Continuous-mix trol (no added fibe r ingredient; Fig. Ia) had a fine bread. US Len. Pat. 3,411 ,9 19 .

494 Hi gh fiber bread

Hall OM , Sayre JG . (1969). A scanning electron R . Moss : Many references arc made to differen ces in microscopy study of starches. Part I. Root and tuber thickness of gluten films; where an d how were the se starches. Textile Res. J. 39: 1044- 1052. measu reme nts made? It would be helpful if the authors Khoo U , Christianson DO, In glett GE. ( 1975) could labe l figures to illustrate differences in film Scanning and tran sm ission microscopy of dough and thickness. bread. Baker's Dig. 49(4): 24-26. Authors: We made numerous observations of the se Pomeranz Y, Shogren MD, Finney KF, Bechtel breads. We observed differences in the number, thi ck­ DB . ( 1977). Fibe r in bread making - effects on fun ctional ness and in th e integrity (breakage) of gluten strands properties. Cereal Chem. 54: 25-41. be tween breads made with th ese different treatments. Pomeranz Y, Meyer D. ( 1984). Li ght an d scan­ Unfortun ately, we do not have th e capa bility to take ning electron mi croscopy of wheat- and rye-bread actua l mea sureme nts from th e SEM or to digiti ze these crumb. Interpretation of speci mens prepared by vari ous images so th at we cou ld do computer image anal ysis and methods. Food Microstruc. 3: 159- 164. obtain this informat ion. This is one of the reasons that Rasco BA, Rubenthaler G, Borhan M, Dong FM. the baking and dough development data is important, ( 1990). Baking propenics of bread and cookies incorpo­ since the baking data provide an indication of the rating distillers' or brewer's grai ns from wheat or strength of a gluten network in a dough. barley. J . Food Sci. 55 : 424-429. Rasco BA , Borhan M, Yegge JM , Lee MH , P. Res mini: The authors discuss about the handling dif· Siffring K, Bruinsma B. ( 1991). Evaluation of enzyme ficulties in industrial producti on of doughs with high and chemically treated wheat bran ingredien ts in yeast­ levels of wheat bran :ca rrageenan blends. They shou ld raised breads. Cereal Chern. 68 : 295-299. also exami ne the influence of the tes ted levels of fiber Shaw JJ , Sharma SC. ( 1989). Ingestible aggregate on the organoleptic characteristics an d on the acceptabil­ and delivery system prepared therefrom . US Lclt. Pat. ity of this type of bread. 4 .851,392. Author s: We have examined the se nsory charac teristics She lt on DR , D' Appoloni a BL. ( 1985). Carbohy­ of these breads. Crumb grain sco res arc a senso ry meas ­ drate functionality in th e baking process. Ce real Food s ure of texture conducted by an expert panel. We have World 30: 437-439. some oth er data on th e senso ry propert ies of similar hi gh fiber breads wh ich we have not included as part of thi s Di scussion with Reviewers paper beca use we felt that it was not rel eva nt.

R. Moss : Although one recognizes th at limitations are P. Res mini: Was th e dried specimen cu t by a razor or imposed by time. availabi lity of equipment and other re­ was it fractu red without mechanical tools? In this last source restncllons, I would like to note th at i t wou ld case, the fracture plane will expose the surface delimit­ have been useful to have in luded micrographs of the ing large air ce lls (i.e., more than 50- 100 ~tm ; see Khoo dough , particularly as the authors indicate that dough et o/., 1975; Pomeranz and Moyer, 1984). development was difficuh to monitor. The incorporation Authors: We cu t a sma ll sl ice from lyophilized breads of some light microscopy would also have been useful to with a razo r and took slices from crumb edge so that confirm whether coa ting material was gluten of ca rragee­ samples would be consistent between treatments. Any nan. artifacts that may have been introduced should have been Authors: We did not have the capability to examine the consistent from treatment to treatment. doughs by SEM . The commercial baking facility where all the doughs were prepared was 60 miles from th e P. Res mini: In no case do the bread images exhibit th e universi ty. We had no way of ensuring tha t any doughs large gas ce lls observed in th e literature citations, but we would exam ine in SEM wo uld be represe ntative of only very small air cells. These gas cells arc quite what was 'baked off', by th e time we we re able to get similar to the "perforations of glu ten film'' shown by the doughs back to the un i ve rsity, get them properl y Angold [Cereal and Bakery products. In: Food Micros­ frozen, and lyophilized for SEM examination , many copy. Vaughan JG (ed.). Academic Press, 1979, 75). changes could have taken place. Use of light micros­ Pl ease comment. copy would not make it any easier to discern whet her Authors: One of our premises was that the breads made coating material wa s gluten or carrageenan unless th ere with the ca rrageenan laminates had larger number of were specific sta ining procedu res of which we arc not sma ll ai r cells than breads which contained wheat bran awa re. but no added ca rrageenan. You have appa rently noticed Obtaining a good measu rement for an optimal mix the same thing. Pressure equilibration, and the number time (dough development) for the wheat bran:carragee­ an d type of air cells that this would produce, would be nan blend was difficult because of the way th is particular directly re lated to th e strength of th e gluten network. dough mixed: this was the only treatment where we had We feel that the addition of gum to the fiber bread would any difficulty measuring optimal mix time. the mix times enhance the res ilience of the dough (increa se i ts plastici­ for the other breads were easy to measure. ty) providing strength to the gluien network which is compromised when bran is added. Thi s i s a possibl e

495 p _ R. Belisle, B. A. Ra sco, K. Sifrring and B. Bruinsma reason why we were able to see larger loaf volumes in Authors: We did conduct statistical analyses for water the breads containing the bran:carrageenan laminates or absorption (Table 4), mix time (Table 4), and loaf vol­ blends than in the breads containing the same quantity of ume (Table 5) values using ANOVA (p < 0.05) and the bran. Bran weakens gluten structure either through a Fisher PLSD post-test. Statistical compari sons are re­ 'gluten diluting' effect or because the bran particles ac­ ported for the control and wheat bran containing breads tually puncture air cell s causing them to collapse (very (5% and 10 % nour replacement levels) and the other diffieultto verify) . Adding the gum may have stabilized treatments. air cells allowing then to remain stable without collaps­ ing during dough developm ent or during the early stages M.E. Camire: Recently concerns have been raised re­ o f baking. garding the safety of heated carrageenan in foods, since heat degrades pol ymers into smaller molec ular weight P. Resmini: On the basis of our experience, the pres­ fraction s which irritate the small intestine. Would you ence of fibers generally weaken the dough structure and, expect the combined effects of lamination and baking to consequently, the gluten strength. How do the authors produce such fragmentation in breads containing carra­ account for the presence of thicker gluten strands in the geenan'? fiber breads? Did the mixing test (performed with mixo­ Au thors: We do not expect that there would be signifi­ graph) indicate significative differences between the cant fragmentation of carrageenan using th e lamination control and the fiber-bread mixograms'? I emphasize that process described here. Any food safety problems with the differences in the protein structure (thickness of breads containing carrageenan at th e higher levels used strands, e tc.) are more easily seen on the dough before in these bread formulations ( < 0.01 g carrageenan per baking (sec Khoo eta/., 1975). g of bread) would be sli gh t. Authors: Thicker gl uten strands in fiber breads are from the ai r cells that su rvive. Air cell collapse is M . E. Camire: Why was carrageenan selected as the though t to be one of th e reasons th at bran containing sou rce of soluble fiber in thi s study? Pentosans and breads have a lower loaf volume. other gums may produce similar results. Have you We did not run mixographs as thi s equipment was investigated other gums? not avai lable. Inst ead , we ran farinographs to measure Author·s: We used a number of other sources of soluble dough development. Changes in dough structure before fiber in the lam in ated wheat bran ingredients. These baking may tell you more about the dough structure, but in cluded all of the comm on fo od gum s, modified cellu­ not necessarily what wil l happen to thi s structure during lo se, oat , corn. barley. and a variety of different pec­ the earl y stages of baki ng . We wanted to look at breads tins. We observed the grea test increase in loaf volume because we thought that SEM of the breads might give by usi ng carrageenan. We also observed browning and us a better indication of the role carrageenan might have navor development in some or the la minates containing played in enhancing loaf volu me rather than SEM s of the pectin which carry through to this bread even when doughs. The effect of the ai r cell expansion which oc­ ad ded at low levels ( < 2% o f a laminate) ma king the curs during th e early stages of baking would not have pectin product unsuitable for breads. Some of the wheat been observed if we looked at doughs instead of breads. bran-food gum laminates have unusual rheological prop­ erties which may make th em uscrut in other food appli­ M .E. Camire: Were any statistical analyses applied to cations but which make them diffic ult to use in breads. the findings? The mixing te sts' results are fairl y close, We arc also studying possible applications for some of so readers mi ght like to know the least signifi cant differ­ these wh eat bran-gum laminates in oth er food products. ence among thi s data .

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