Faculty of Food Technology and Biotechnology, University of Zagreb
Abstract
Gluten hydrolysate was prepared through limited enzymatic hydrolysis of wheat gluten resulting from the byproducts of wheat starch. The enzyme applied in the present study was Protamex. Response surface methodology was used to investigate the effects of pH, gluten hydrolysate (GHP)λ-carrageenan (C) ratio and reaction time on emulsifying properties of the GHP-C conjugate. The regression model for emulsion activity index (EAI) was significant at p=0.001, while reaction time had a significant effect on EAI of the conjugate with regression coefficient of 4.25. The interactions of pH and GHP/ C ratio, and GHP/C ratio and reaction time significantly affected the EAI of the conjugate. Both the emulsifying property and nitrogen solubility index (NSI) of GHP-C conjugate prepared under the optimal conditions increased more remarkably, compared to the control. The denaturation temperature of GHP-C conjugate obviously increased compared to wheat gluten. The addition of GHP-C conjugate had different effects on dough characteristics. Moreover, this conjugate can delay the increase in the bread crumb firmness during storage. It demonstrated that this conjugate couldimprove the dough characteristics and had anti-staling properties of bread.Hidrolizat glutena pripravljen je ograničenom enzimskom hidrolizom pšeničnoga glutena dobivenog kao nusproizvod pšeničnoga škroba. U radu je upotrijebljen enzim Protamex. Metodom odzivne površine (response surface methodology) ispitivan je utjecaj pH, odnos gluten hidrolizat (GHP)λ-karagenan (C) i trajanje reakcije na emulgatorska svojstva GHP-C konjugata. Regresijski model za indeks aktivnosti emulzije (EAI) bio je značajan pri p=0,001, a vrijeme reakcije bitno je utjecalo na EAI konjugata s koeficijentom regresije od 4,25. Međusobni odnos pH i GHP/C, te vremena reakcije značajno utječe na EAI konjugata. GHP-C konjugati, pripravljeni pod optimalnim uvjetima, imali su bitno poboljšana emulgatorska svojstva i indeks topljivosti dušika (NSI) u usporedbi s kontrolnim uzorkom. Temperatura je denaturacije GHP-C konjugata vi{a u usporedbi s glutenom. Dodatak GHP-C konjugata različito je utjecao na osobine tijesta. Konjugat omogučava da se duže očuva svježina krušnih mrvica tijekom skladištenja, poboljšaju svojstva tijesta i uspori starenje kruha
