Student University of Manitoba Winnipeg, Manitoba, Canada
Thermal treatment of pea proteins at >82 °C may improve the structural flexibility, hence enhancing its techno-functional performance in food systems. This study investigated how heat pre-treatment of pea protein at different pH values affects soluble polypeptide size and impacts functionality in foods. A 10% (w/v) slurry of a commercial pea protein concentrate (PPC) was prepared using distilled water and adjusted to pH 3, 5, 7 and 9. The mixtures were then heated in a water bath at 100 °C for 30 min, cooled immediately in an ice bath and then centrifuged at 7, 000 x g for 30 min. The supernatant was passed through a membrane with 30 and 50 kDa cut-off to collect the < 30, 30-50 and >50 kDa fractions, which were then compared to the native PPC (control) by analyzing polypeptide composition (SDS-PAGE), protein content, solubility, foaming and hydration properties, surface hydrophobicity and least gelation concentration (LGC). Statistical analysis carried out was three-way ANOVA at a significance level of α≤ 0.05. In comparison to the control, at all test pH, >50 kDa fractions showed improved solubility (>60%), oil holding capacity (>67%), protein content (~7%), foam capacity (>30%), foam stability (>65%), water holding capacity (>9%) and surface hydrophobicity for treatment at pH 9 (~50%). Least gelation concentration of the control was superior to all heat-treated fractions by ~20%. Heat-soluble pea proteins possess superior functionality that could enhance quality of food products such as beverages, baked goods, meats, sausages, yoghurt and whipped toppings.