The ice recrystallization inhibition activity of wheat glutenin hydrolysates and effect of salt on their activity

This study aimed to investigate the antifreeze activity of wheat glutenin hydrolysates produced by Alcalase and trypsin at varying degrees of hydrolysis. The influence of salt concentrations in two dispersing media, phosphate-buffered saline (PBS) and NaCl solution, and the types of cations, NaCl and CaCl2, on hydrolysates was further analyzed. The results revealed a consistently higher ice recrystallization inhibition (IRI) activity for all hydrolysates dispersed in 0.1 x PBS than in 1 x PBS. Interestingly, glutenin hydrolysates exhibited better IRI activity in CaCl2 than in NaCl solution under the same ionic strength. Furthermore, trypsin-derived hydrolysates (with a molar mass about 10 kDa) consistently had better IRI activity than those produced by Alcalase (with a molar mass less than 1 kDa), regardless of the dispersing media. The observed increase in IRI activity was associated with alterations in the secondary structure, characterized by a higher α-helix and lower β-turns content. This suggests that structural rigidity of the molecules plays a significant role in enhancing the antifreeze activity of peptides. Additionally, the scores plot of the partial least-squares discriminant analysis model indicates that salt concentration had a more significant impact than salt type on the IRI activity of glutenin hydrolysates. In conclusion, our findings provide insights into the factors influencing the IRI activity of protein hydrolysates.