AbstractBACKGROUNDTransglutaminase (TGase) is a heat‐resistant biocatalyst with strong catalytic activity, which functions effectively under moderate temperature and pH conditions, and is used widely in protein cross‐linking and recombination. Transglutaminase cross‐linking is a novel and specific modification method for black bean protein isolate (BBPI). This article investigates the effect of transglutaminase cross‐linking on the structure and emulsification performance of heated BBPI.RESULTSSodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) analysis showed that heated BBPI with TGase had a higher molecular weight than heated BBPI without TGase, and the protein bands widened with increasing enzyme activity, indicating that TGase cross‐linking promoted protein molecule aggregation. A high molecular weight polymer can better stabilize the oil–water interface, preventing the emulsion from layering. Fourier transform infrared (FTIR) spectroscopy showed that the α‐helix content decreased from 15.64% to 13.75%, and the β‐sheet content increased from 48.13% to 54.08%. The decrease in α‐helix content and increase in β‐sheet content could make the structure more stable and improve the emulsifying properties of heated BBPI. When TGase was 20 U g−1, the protein emulsification activity index (EAI) reached its highest value of 1.87 m2 g−1, and the emulsification stability index (ESI) value was 0.27 min (P < 0.05); these figures were 0.19 m2 g−1, and 0.07 min higher, respectively, than in the sample without added TGase.CONCLUSIONIn summary, transglutaminase cross‐linking has a positive effect on the structure and emulsification performance of heated BBPI and can be used as an effective method for BBPI modification. © 2024 Society of Chemical Industry.
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