Functional properties of a cross‐linked soy protein–gelatin composite towards limited tryptic digestion of two extents
2013
Sheng, Wen‐Wen | Zhao, Xin‐Huai
BACKGROUND: Both enzymatic cross‐linking and hydrolysis are used to treat food proteins for functionality modification. The present study aimed to reveal the impact of limited tryptic digestion on some functional properties of a cross‐linked composite generated from soy protein isolate and gelatin by transglutaminase. RESULTS: The composite was digested by trypsin for 1.5 and 4 h to produce two hydrolyzed composites with degrees of hydrolysis of 1% and 2%, respectively. Electrophoretic and chemical analysis showed that only part of the composite was degraded, and the gelatin fraction in the composite was more sensitive to tryptic digestion than the soy protein fraction. The hydrolyzed composites exhibited higher protein dispersion index at pH 4.5 or 7.0 and surface hydrophobicity, better digestibility in vitro, emulsifying property and oil absorption capacity, but lower water holding capacity and rheological properties (apparent viscosity, storage and loss modulus) than the composite. Compared to soy protein isolate, the hydrolyzed composites had better rheological properties, and higher water‐holding capacity and emulsion stability index. CONCLUSION: The applied tryptic digestion conferred some improved properties on the hydrolyzed composites compared with the composite or soy protein isolate, and has potential for obtaining a new functional ingredient for processed foods. © 2013 Society of Chemical Industry
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