Influence of protein type, content and polymerization on in vitro starch digestibility of sorghum noodles.

Affiliation

Liu FY(1), Yang Z(1), Guo XN(1), Xing JJ(1), Zhu KX(2).
Author information:
(1)State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, Jiangsu Province, PR China; School of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, Jiangsu Province, PR China.
(2)State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, Jiangsu Province, PR China; School of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, Jiangsu Province, PR China. Electronic address: [Email]

Abstract

The impacts of protein type, content and polymerization on in vitro starch digestibility of cooked sorghum noodles were investigated. Results showed that addition of exogenous proteins decreased the starch hydrolysis rate. The noodles added wheat protein (WP) exhibited the highest amount of resistant starch, followed by whey protein isolate (WPI) and egg white protein (EWP). In each group, the hydrolysis kinetic parameters were the lowest when protein addition amounts were 5% WP, 3% EWP and 3% WPI, respectively. These changes were ascribed to the interactions of starch-proteins and protein-proteins, as proved by the enhancement of protein polymerization and starch short-range structure. The increase of protein polymerization degree induced by disulfide cross-links reduced the starch digestion rate of noodles. Additionally, the confocal laser scanning microscope observations demonstrated that the strengthening of protein network had a positive effect on decreasing starch digestibility by preventing the accessibility of enzymes to starch.