doctoral thesis
Influence of enzymes, hydrocolloids and emulsifiers on bread staling kinetics

Marko Jukić (2009)
Josip Juraj Strossmayer University of Osijek
FACULTY OF FOOD TECHNOLOGY
Department of Food Technologies
Sub-department of Cereal Technology
Metadata
TitleUtjecaj enzima, hidrokoloida i emulgatora na dinamiku procesa starenja kruha
AuthorMarko Jukić
Mentor(s)Žaneta Ugarčić
Abstract
Starenje kruha je složen proces koji uključuje više fizikalno-kemijskih promjena koje uzrokuju različita nepoželjna svojstva, kao što su povećanje čvrstoće i isušivanje sredine kruha, promjene u kori, gubitak i promjene arome i dr.. Smatra se da je za povećanje čvrstoće, odnosno za proces starenja pekarskih proizvoda na molekularnoj razini najodgovornija retrogradacija škroba, u prvom redu retrogradacija amilopektina iz potpuno amorfnog stanja, kakav se nalazi u svježem kruhu, u djelomično kristalično stanje, ali bitna je i uloga drugih čimbenika kao što su gluten, lipidi, voda, neškrobni polisaharidi itd. Cilj istraživanja bio je ispitivanje utjecaja različitih dodataka, kao što su enzimi maltogena α- amilaza srednje termostabilnosti i 1,3-specifična lipaza s lipaznim i fosfolipaznim djelovanjem, hidrokoloid karboksimetilceluloza (CMC) i emulgator ester diacetil vinske kiseline i monoglicerida (DATEM), na dinamiku procesa starenja kruha. Osim toga, ispitan je i utjecaj tih dodataka u ovisnosti o različitom stupnju oštećenosti škroba uzoraka brašna koja su se koristila u izradi kruha. Provedena su probna pečenja, a tijekom sedam dana skladištenja pratila se migracija vode iz sredine u koru kruha, intenzitet rekristalizacije amilopektina primjenom diferencijalne motridbene kalorimetrije (DSC), ispitan je teksturalni profil kruha pomoću analizatora teksture, a provedena su i amilografska ispitivanja vodenih suspenzija sredine kruha i određivanje rezistentnog škroba u kruhu tijekom starenja. Provedena je i nelinearna estimacija eksperimentalnih podataka prema Avramijevom modelu kristalizacije polimera. Rezultati su pokazali da povećani stupanj oštećenosti škroba značajno povećava čvrstoću svježeg kruha. Dodatak enzima, CMC-a i DATEM-a smanjuje početnu čvrstoću kruha, a najveći utjecaj na teksturu svježih uzoraka ima kombinirani dodatak α-amilaze i lipaze koji uzrokuje i najmanju promjenu čvrstoće, elastičnosti i kohezivnosti tijekom starenja. Sinergijski učinak α-amilaze i lipaze na usporavanje brzine starenja potvrđen je i određivanjem entalpije taljenja rekristaliziranog amilopektina, odnosno entalpije retrogradacije ΔH pomoću diferencijalne motridbene kalorimetrije. Najizraženije promjene u amilografskim ispitivanjima vodenih suspenzija kruha tijekom starenja očituju se u smanjenju izmjerenih vrijednosti opadanja viskoznosti tijekom zadržavanja temperature na 95 °C. Najveće smanjenje opadanja viskoznosti imali su uzorci bez dodataka, a najmanje uzorci s kombiniranim dodatkom enzima.
Keywordsbread amylopectin thermophysical properties amylographic studies
Parallel title (English)Influence of enzymes, hydrocolloids and emulsifiers on bread staling kinetics
Committee MembersDrago Šubarić (committee chairperson)
Žaneta Ugarčić (committee member)
Dubravka Hackenberger (committee member)
Zorica Jurković (committee member)
GranterJosip Juraj Strossmayer University of Osijek
FACULTY OF FOOD TECHNOLOGY
Lower level organizational unitsDepartment of Food Technologies
Sub-department of Cereal Technology
PlaceOsijek
StateCroatia
Scientific field, discipline, subdisciplineBIOTECHNICAL SCIENCES
Food Technology
Engineering
UDK664
APPLIED SCIENCES. MEDICINE. TECHNOLOGY
Production and preservation of solid foodstuffs
Study programme typeuniversity
Study levelpostgraduate
Study programmeFood Engineering
Academic title abbreviationdr. sc.
Genredoctoral thesis
Language Croatian
Defense date2009-07-17
Parallel abstract (English)
Bread staling process involves several physico-chemical changes that produce different undesirable properties like firmness increase, drying of bread crumb, odour changes etc. It is considered that the most responsible process for bread staling at the molecular level is starch retrogradation, mainly amylopectin retrogradation from amorphous to semi-crystalline state. Role of gluten, lipids, water and non starch polysaccharides are also important. The objective of this research was to investigate influence of maltogenic α-amylase, 1,3- specific lipase with both lipase and phospholipase activity, hydrocolloid carboxymethylcellulose (CMC) and emulsifier diacetyl tartaric acid ester of monoglyceride (DATEM) on bread staling process. Influence of flour starch damage degree was also investigated. Following analyses were conducted during seven days of bread storage: monitoring of moisture migration from crumb to crust, determination of amylopectin recrystalisation with differential scanning calorimetry (DSC), texture profile analyses (TPA) and amylographic investigation of bread slurries. Nonlinear estimation of experimental data was carried out according to Avrami model of polymer crystallisation. Obtained results showed that larger degree of starch damage significantly increased while addition of enzymes, CMC and DATEM decreased initial firmness of bread. The greatest influence on texture of fresh samples and smallest change of firmness, resilience and cohesiveness during staling were caused by combined addition of α-amylase and lipase. Synergistic effect of these enzymes was confirmed by DSC determination of retrogradation enthalpy ΔH. Decrease of breakdown viscosity was the most noticeable change of amylografic parameters during bread staling. Control samples without additives had largest and samples with combined enzymes addition had smallest decrease of breakdown values.
Parallel keywords (Croatian)kruh amilopektin termofizikalna svojstva amilografsko ispitivanje
Extent134 str.; 30 cm
Versionaccepted version
Resource typetext
Access conditionAccess restricted to students and staff of home institution
Terms of usehttp://rightsstatements.org/vocab/InC/1.0/
Noteaccepted version
URN:NBNhttps://urn.nsk.hr/urn:nbn:hr:109:525389
CommitterIvana Šuvak