Effect of pH-shifting method on solubility and emulsifying properties of soy protein concentrate

Abstract

The purpose of the current study was to investigate the influence of pH shifting process on soy protein concentrate to improve its functional properties. In this work, pH of the soy protein concentrate was adjusted to pH 2, 3, 4, 10, 11, and 12 prior to neutral pH (pH 7). pH-shifting process effectively improved the solubility of soy protein concentrate, whereas the modification of the samples with the acidic conditions was less pronounced. The alkaline pH values (pH 10, 11, and 12) showed higher solubility compared to the acidic pH values (pH 2, 3, and 4). With the pH 12 treatment, approximately 30 times higher solubility was achieved. Among the treatments, the pH 12- treated samples showed the improved emulsifying properties with the highest emulsifying activity and stability indexes. All pH treated samples (pH 2, 3, 4, 10, 11, 12) showed less turbidity with smaller particle sizes where the untreated samples showed most turbid structure with the biggest particle size.