Effect of enzymatic modification on the film-forming properties of soy protein isolate
Abstract
The effect of enzymatic treatment on the film-forming properties of soy protein isolate was studied using transglutaminase, alcalase, α-chymotrypsin and pepsin. Reaction conditions were optimized by applying 2 concentrations of enzyme (E/S = 0.2 and 0.5%) at a constant concentration of substrate (5%, wt/wt) while controlling temperature and pH and by studying effect of various hydrolysis times (1, 5, 10, 20, 30 and 60 min). The hydrolysates were analyzed by determining the degree of hydrolysis and by studying sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns. Film-forming solutions were made from each enzyme-treated sample containing 5% (wt/wt) protein and 3% (wt/wt) glycerol with final pH 9.0 ± 0.1. Transglutaminase-modified films had significantly (p < 0.05) higher % elongation at break (E) and lower tensile strength (TS) than control films. The average E value of transglutaminase-modified film was more than 2 times greater than that of control film. Films treated with alcalase, α-chymotrypsin and pepsin resulted in lower E and TS than those of control film (p < 0.05). No significant differences were observed in film thickness among all films (p > 0.05). Modification of soy protein isolate by pepsin resulted in considerably decreased % elongation and tensile strength compared to other films. No significant (p > 0.05) differences in % elongation were found between alcalase and α-chymotrypsin treatment.
Description
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Includes bibliographical references (leaves 53-57).
Issued also on microfiche from Lange Micrographics.
Includes bibliographical references (leaves 53-57).
Issued also on microfiche from Lange Micrographics.
Keywords
food science and technology., Major food science and technology.