Protein Processing from Amazonian Leaf-Cutter Ants (Atta laevigata) Through pH-Shifting: Electrophoretic Profile Changes, Gastrointestinal Digestion, and In Vitro Membrane-Stabilizing Activity

The growing interest in alternative protein sources has driven research into edible insects as sustainable raw materials for food and bioprocessing applications. In this study, protein concentrates were produced from Amazonian leaf-cutter ants (Atta laevigata) through a pH-shifting approach and characterized. Ant flour was subjected to alkaline solubilization at pH 10.0 and 12.0, followed by precipitation at pH 2.0–5.0. Proximate composition, concentrate yield, and protein content were determined, while protein profiles and changes during standardized static in vitro gastrointestinal digestion were assessed by SDS–PAGE. The functional potential of native proteins and digestion products was evaluated using an in vitro erythrocyte membrane stabilization assay. Significant differences in protein concentrate yield and protein content were observed among the pH-shifting conditions, with the highest protein contents obtained at solubilization pH 12.0 and precipitation pH 4.0–5.0. SDS–PAGE revealed distinct protein fractions and a progressive reduction in detectable protein bands during gastrointestinal digestion. Gastric digests exhibited enhanced in vitro membrane-stabilizing activity compared with the undigested protein concentrate, whereas intestinal digestion substantially reduced this activity. These findings demonstrate the potential of pH-shifting for concentrating A. laevigata proteins and show that gastrointestinal digestion markedly influences their measured in vitro biofunctional activity.