The gel mechanism and carrier quality of fibrous and granular whey protein self-assembly

In this study, we induced a 6% protein concentration of whey protein (WP) to form fibrous and granular whey protein self-assembly (FWS and GWS respectively) by a pH-temperature gradient. The fibrous and granular whey protein self-assembly were used as raw material to explore the mechanism of gel formation and their potential a new delivery system loaded with Epigallocatechin gallate (EGCG) was evaluated. Compared with native WP, the α-helix decreased, and the β-sheet increased in FWS, while the opposite was found in GWS. The hydrophobic interaction played a crucial role in the formation process of FWS and GWS, while disulfide bonds played a slightly more vital role in the formation process of GWS. The gels prepared by FWS and GWS had denser microstructure and stronger mechanical strength than native WP gel. Both the water holding capacity and hardness of the gels prepared by FWS and GWS were significantly higher than those prepared by native WP. The water holding capacity of the gel prepared by FWS was higher than that of the gel prepared by GWS at the same protein concentration, but the hardness results were the opposite. Hydrophobic interaction and hydrogen bonds played a dominant role during the gel formation process of FWS and GWS, while disulfide bonds only played a role in the gel formation process of GWS. In addition, the gel formed by FWS and GWS had higher epigallocatechin gallate encapsulation efficiency (94.40% and 95.09%, respectively) and a slow control effect during digestion. Therefore, gel prepared by FWS and GWS can provide essential ideas for building new protein gel technology and is expected to be an ideal carrier for bioactive substances.