Thermal aggregation of almond protein isolate

Almond protein isolate (API) formed a gel at 90 °C in 5 min at a concentration of 4% (w/v) in distilled deionized water adjusted to pH 8.2. The rate of API aggregation was dependent on the composition of the heating medium. Adding NaCl, NaBr, NaI, NaF, or NaSCN (each at 0.25, 0.5, 0.75, and 1 M) to the heating medium decreased the rate of thermal aggregation of API, while addition of 1 M CaCl2 promoted it. Hydrophobic interactions helped stabilize the API against thermal aggregation. Hydrogen bonds, ionic interactions, and disulfide exchange promoted the API thermal aggregation. Contribution of disulfide exchange to the API thermal aggregation was more than that made by the hydrogen and ionic bonds.