LAUSR

BACKGROUND Protein-polysaccharide gels have significant and unique properties in food formulations. However, they are susceptible to environmental influences like heat and pH. The present work investigated the effects of acid and alkali treatments on the gel properties and microstructural changes of whey protein isolate (WPI)-high acyl gellan gum (HG). RESULTS Results showed that the pH value had a remarkable effect on the gel hardness, water holding capacity (WHC), free sulfhydryl groups (-SH), and other properties of the composite gel. The hardness reached the highest of 282.50 g and the best WHC of 98.33% at pH 7, indicating that a suitable pH could promote this cross-linking between the WPI and HG molecules. The rheological analysis demonstrated that the pH affected the gel formation time. Meanwhile, the gel formation time reached the longest at pH 7, and the gel's storage modulus G' value was the largest. FTIR results showed that pH affected the interaction between WPI and HG. In addition, SEM analysis presented that the composite gel started a three-dimensional network structure at pH 7-9. CONCLUSION These results could broaden the application of protein-polysaccharide gels in food and delivery systems. This article is protected by copyright. All rights reserved.