Tomato Juices and Tomato Juice Concentrates: a Study of Factors Contributing to Their Gross Viscosity
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Tomato juices and tomato juice concentrates: a study of factors contributing to their gross viscosity CENTRALE LANDBOUWCATALOGUS 0000 0174 1715 m mi BISLI0T3BEK DER LANDPO'CVHOOKSCHOOL Promotor: dr. W. Pilnik, hoogleraar in delevensmiddelenlee r Co-promotor: dr. ir. A.G.J. Voragen, wetenschappelijk hoofdmedewerker ^JfVJO ??oi,'^' R. Heutink Tomato juices and tomato juice concentrates: a study of factors contributing to their gross viscosity Proefschrift ter verkrijging van de graad van doctor in de landbouwwetenschappen, op gezag van de rector magnificus, dr. C.C. Oosterlee, in het openbaar te verdedigen op woensdag 8 oktober 1986 des namiddags te vier uur in de aula van de Landbouwuniversiteit te Wageningen H i / 0' J ^u9p?o, , fo9 STELLINGEN 1. Dedoo r Shomer et al. (1984) gesussereerde rol van endogeen cellulase bij het uitzakken van deeltjes in tomatensap wordt niet ondersteund door de in de literatuurvermeld ecellulas ehoeveelhede ni nd etomaat . Shomer,I. ,P . Lindnere nR . Vasiliver,198 4 Journalo f FoodScience ,49:628-63 3 2. Geziend egroott eva nd edeeltje s ishe ttwijfelachti g of Raoe t al.(1986 )d ejuist e meetgeometriegebruike nvoo r hunrheologisch e metingenaa n appelmoes. Rao, M.A., H.J.Cooley ,J.N .Nogueir ae nM.R .McLellan ,198 6 Journalo f FoodScience , 51:176—179 3. Bij het gebruik van polysaccharide-afbrekende enzymente r opheldering van de structuurva npolysaccharide n moetmee raandach tworde n besteed aan: 1)d ezuiverhei dva n hetenzym , 2)d ezuiverhei dva nd esubstrate ndi e worden gebruiktvoo r het karakteriserenva nhe tenzy me n3 )ee nmogelijk emultisubstraa t specificiteitva nhe tenzym . 4. De vorming van hydroxymethylfurfural is geen bruikbare indicator voor het optredenva nniet-enzymatisch ebruinkleurin g invruchtesappen . 5. Alleen door het geven van uitgebreide voorlichting kanworde n bereikt dat de consument bestraling van voedingsmiddelen alsee nalternatiev e conserverings- methode aanvaardt. Het effect van een voorlichtingscampagne zal worden tenietgedaan wanneer dit proces in verhullende benamingen op het pirodukt wordtgedeclareerd . 6. Het zich toeeigenen van het woord significant door statistici kanto t verwarring leiden wanneer dit woord in het Engels wordt gebruikt in de betekenis van veelbetekenend. 7. De viscositeit van tomatensap en concentraten daarvan wordt grotendeels bepaalddoo r hetgehalt eaa n wateronoplosbare bestanddelen. Dit proefschrift 9. Een enzymatische hydrolyse met een mengsel van pectolytische en cellulo- lytische enzymen, voorafgaand aan een chemische hydrolyse met 2N TFA is noodzakelijk om de neutrale suikersamenstelling in tomaten WIS te kunnen bepalen. Dit proefschrift BIBLIOTHEEK DER LAHDBGUWHOGESCHOOI WAGENINGEN 10. Het is mogelijk om tomatensap te concentreren zonder dat naverdunnin g van het concentraat een verlies in viscositeit ten opzichte van het ongeconcen- treerdesa pza l optreden. Ditproefschrif t 11. Verschillen inviscositei t tussenho t breake ncol d breaktomatensa pworde n niet alleen veroorzaakt door de snelheid van enzym-inactivatie maar ook door de temperatuurtijden s hetpasseren . Dit proefschrift 12. Het gebruik van microscopische technieken om veranderingen in voedings- middelen vast te stellen kan gemakkelijk leiden tot "wishful seeing" als variant van"wishfu lthinking" . Abstract R. Heutink, 1985.Tomat o juices and tomato juice concentrates:a study of factors contributing to their grossviscosity .Doctora lThesis , AgriculturalUniversity ,Wageningen ,Th eNetherlands . The grossviscosit y of tomato juice and tomato juice concentrateswa s found tob e determined primarily by thewate r insoluble solids (WIS)content . The serumviscosit y did not contribute to grossviscosity . TheWI S consisted ofwhol e tomato cells,vascula r bundles and skin fragments. In general theWI S could be fractionated into 40-45% pectin, 25-30% hemicellulosean d 30-35% cellulose.Highl ybranche d aswel l asmor e linear pectin fragmentswer e found tob e present in tomatoWIS .Xylans , arabinans and (arabino)galactans were involved in the attachment of pectic substances to the cellwal lmatrix .Th e presence ofxylans ,xyloglucans , (gluco)mannansan d a limited amount of galactan in thehemicellulos e was indicated. Pectin fragments,characterize d by a low content of arabinose and galactose containing side chains,an d esterified in such awa y that theywer e degraded bybot h PG and PL,mad e an important contribution to grossviscosity . Cellulosewa s found tomak e a relatively smaller contribution togros sviscosit y than these pectin fragments.Th e rigidity of the cellwalls ,cause d by the cellulosic structure,seeme d to influence grossviscosit y athighe rWI S concentrations.Th e differenceswhic h exist naturally inWI S compositionwer e found tob e too small to cause large differences ingros sviscosity . Higher hotbrea k temperatureswer e found to result in amor e effective removal ofWI S from skinmaterial .Th e influences ofho tbrea k temperature,finishe r temperature and size of finisher screen opening on the finisher operationwer e closely related to the efficiency of the finisher.Th e concentration of a tomato juice by evaporation resulted in a loss in grossviscosity ,afte r dilution of the paste to the original strength.Th e causes for this "dilution-loss"wer e studied and could be related to the simultaneous concentration of tomato cells and,presumably , ions.Th e centrifugation-serum-concentrationmetho d resulted in a significantly decreased "dilution-loss". Curriculum vitae RobHeutin kwa sbor n inEnschede ,th eNetherlands ,o n the 29th ofMa y 1956. From 1974 to 1980h e studied food science and technology at the Agricultural University ofWageningen ,th eNetherlands . In 1980h e obtained the degree ofMaste r of Science,cu m laude,wit h majors in food chemistry and foodmicrobiolog y andwit h amino r in toxicology. From October 1980 to May 1985 heundertook , in theDepartmen t of Food Science of the AgriculturalUniversity ,Wageningen ,th eH.J . Heinz Co. funded research work presented in thisthesis . Acknowledgemen ts Thewor kpresente d inthi sthesi swa scarrie dou tunde rth eguidanc e ofProf .Dr .W .Pilnik ,Hea do fth eLaborator yo fFoo dChemistr yo fth e Departmento fFoo dScienc eo fth eAgricultura lUniversit yo fWageninge ni n theNetherlands .I remai nver ygratefu lt ohi mfo rpersuadin gm et oaccep t thechalleng eo fthi sPh.D .study .Hi sinspiratio nan dnumerou sidea swer e ofgrea tvalu et oth ecompletio no fthi sthesis . Ia mals over ygratefu lt om yco-promoto rDr .Ir .A.G.J .Vorage nfo r manyhour so ffruitfu ldiscussio nan dfo rhi scritica lrevie wo fth e manuscript. Ia mindebte dt oDr .Ir .F.M .Rombout sfo rth estimulatin gdiscussion s andfo rhi scarefu lreadin go fth ereport sprepare d inth ecours eo fthi s study. Iwoul dlik et othan kth eH.J .Hein zCo. ,Pittsburgh ,US Afo r initiatingan dfundin gthi sproject .I woul despeciall y liket othan kMr . A.Nip ,Dr .Ir .P .Folstar ,Dr .K .Venka tan dMr .S .Martine zfo rthei r contributiont othi sresearch . Iwoul dlik et oexpres sm ygratitud eto :Mis sG .Lokhors tfo rhe r skilfulassistenc ei nanalysin gth esamples ;Ir .G .va nd eHoe kan dIr .B . vanValkengoe d forthei rstudie so nth esubject sdiscusse d inchapter s4 and5 ;Mr .H .Schol sfo rstudyin gth estructura lfeature so fth e hemicellulosei ntomatoe san dfo ral lhi sassistenc ei ngeneral ;Dr .H.A.I . Siliha,m yfello wdoctora lscholar ,fo rhi sfriendshi pan dfo rth e interestingdiscussion so nbot hth eclou dstabilit yo faprico tnecta ran d thegros sviscosit yo ftomat oproducts ;Mrs .M.J.F .Searle-va nLeeuwe nfo r purifyingth eenzyme suse di nth eexperimenta lwork ;th eentir estaf fo f theDepartmen to fFoo dScienc efo rbein gfantasti ccolleague san dfo ral l theirassistence ;Mr .M .Schimme lfo rpreparin gth edrawings ;Mr .W .va n Hoffo rpreparin gth ephotographs ;Mis sJ .Mulde rfo rtypin gth emanuscrip t andMis sJ .Truijen sfo rcorrectin gth eEnglis htext . FinallyI wan tt othan kJolanda .Withou the rpatience ,understandin gan d encouragementthi sthesi swoul dno thav ebee nwritten . SUMMARY The subject and objectives of thepresen t study are introduced in chapter 1. The relevant data from the literature are discussed in chapter 2. This literature review covers topics such as:th eproduction ,genera l composition and processing of tomatoes (2.1.); definitions and quality parameters for tomato products (2.2.); factors contributing to the gross viscosity of tomato products (2.3.); factors affecting serum separation in tomato products (2.4.)an d the composition of tomato polysaccharides (2.5.). For convenience the lengthy and extensive review on the factors contributing togros sviscosit y of tomato products is summarized in2.3.1 . The general analyticalmethod s used throughout this study are presented in chapter 3. Special attention hasbee n paid to a comparison of twomethod s ofmeasurin g grossviscosit y and to thedeterminatio n of the neutral sugarspresen t in tomatoWIS . Itwa s found that the Bostwick consistometer isno t sensitive enough formeasurin g high-viscosity tomato products. This instrument,however , isver y suitable formeasurin g the grossviscosit y of tomato productswit h a Bostwick flowo f 5 cmo rmore . Thehydrolysi s of thepolysaccharide s in tomatoWI Swit h 0.8 N H SO, or 2N H SO,,bot h after prehydrolysiswit h 72%H SO,,di d not result ina n adequate determination of theneutra l sugars.Prehydrolysi s of the polysaccharides with an enzymemixtur e containing pectolytic and cellulolytic enzymes,prio r tohydrolysi swit h 2N TFA, increased in particular the amounts of glucosewhic h were determined. The influence of soluble solids (serumviscosity ) and insoluble solids on thegros sviscosit y of tomato juice and concentrates isstudie d and discussed in chapter 4.Th e samples analysed differed invariet y and methods of processing (break temperature and concentration).Th e gross viscosity of tomato juices and concentrateswa s found tob e determined primarily by theirWI S content.Variet y andmetho d ofprocessin g influenced grossviscosit y at a specific °Bxb y affecting the amount ofWIS .Gros s viscosity at a specificWI S amountwa sno t influenced by variety, serum viscosity ormetho d ofprocessin g unless themetho d of processing resulted indegradatio n of theWIS .