Effect of gelation pH on whey protein aerogel properties

Abstract Due to their bioinspired self-assembly and biocompatibility, protein-based aerogels have drawn growing interest in biomedical applications. With its excellent gelling and self-assembly properties, whey protein isolate (WPI) represents a promising source for the fabrication of biodegradable and homogeneous tunable aerogels. Gelation pH has a significant impact on the morphological homogeneity of protein biomaterials, which is essential for controlling tissue-implant interactions. In this study, WPI aerogels were produced without gelation-induced agents (followed by a supercritical CO 2 drying process), and the effect of the gelation pH was investigated by varying its value from 2 to 11. Aerogels with a high fluid absorption capacity ( ~ 760%), specific surface area (312 m 2 . g −1 ), and pore volume (1.02 cm 3 . g −1 ) were obtained by gelation at neutral to mildly alkaline conditions (pH 7-8.5). Because of their excellent fluid absorption capacity, these aerogels have the potential to be a biocompatible wound dressing. On the other hand, aerogels from acidic gelation conditions (pH < 3) dissolved or disintegrated during fluid absorption. Monolithic aerogels were obtained by increasing the gelation pH. However, as the gelation pH approached the WPI isoelectric region (pH 4-6) or extreme alkaline pH (pH ≥ 9), aerogels presented low specific surface area and fluid absorption capacity. Overall, this study confirms that gelation pH affects the structural and functional properties of WPI aerogels and offers a systematic investigation of the effect of gelation pH on the resulting aerogels.