Preparation and Properties of Acid‐Modified Sunflower Protein Isolate

Sunflower protein isolate (SFPI), 1–10% w/v dispersion, was heated in HC1 (0.025–0.1M) at 90°C. Extents of deamidation and peptide bond hydrolysis were a function of both acid and protein concentration. SDS gel electrophoresis indicated that acid modification of SFPI induced cleavage of a major protein component of molecular weight about 66,000 daltons into two smaller components. Acid modification decreased the isoelectric point of the protein and resulted in a marked increase in solubility at near neutral pH values. Acid‐modified SFPI, soluble at pH 7, was successfully incorporated into a model infant formula. Acid modification also improved foam expansion and foam stability properties of SFPI.