MAILLARD INDUCED PEA PROTEIN-POLYSACCHARIDE CONJUGATES: A FUNCTIONALLY ENHANCED INGREDIENT FOR THE FOOD AND BEVERAGE INDUSTRY

Pea proteins are increasingly recognized as a cost-effective, sustainable source of legume proteins with a well-balanced amino acid profile. The primary goal of this research was to enhance the functional properties of pea proteins by combining enzymatic hydrolysis with Maillard conjugation, using starch and other carbohydrate fractions from air-classified pea flours. The process was designed to be environmentally sustainable, relying on food-grade enzymes and heat-induced Maillard reactions, eliminating the need for enzyme inhibitors and supporting a "green label" approach. In the first study, pea protein-enriched flour (PPEF) was hydrolyzed using trypsin and papain to achieve low to medium degrees of hydrolysis (2% – 15%). These hydrolysates were then conjugated with residual starch and non-starch polysaccharides within the PPEF through heat conjugation by the Maillard reaction. The resulting conjugates showed improved functional properties compared to the raw samples, particularly foaming (~20% - 40%) and emulsifying capacities (~2% - 14%), with enhanced stability (3% - 28%) at acidic pH. Water-holding capacity was improved by ~42% - 100% and oil-holding capacity also increased by about 72% - 254%. The second study focused on obtaining conjugates having higher degrees of hydrolysis (above 15%) of the pea proteins, with additional carbohydrate hydrolysis using α-amylase. These hydrolysates were then heat-conjugated with intact starch and other carbohydrates in the flour, including non-starch carbohydrates. The trypsin-hydrolyzed conjugates outperformed papain-hydrolyzed ones across a range of pH levels (4, 7, and 10), demonstrating superior foaming (60% - 90%) and emulsifying (~ 6% - 210% improvement) properties whereas water-holding and oil-holding properties did not show any significant differences. Contrary to previous findings in the literature, the research showed that extensive hydrolysis, when combined with Maillard conjugation, did not impair functionality but enhanced it. In the third study, both fine and coarse fractions from air classification, i.e., protein- and starch-rich flour, were hydrolyzed using trypsin and α-amylase, respectively, and conjugated using heat through the Maillard reaction. Molecular weight analysis indicated a shift towards higher molecular weights, while microstructural analysis revealed protein-protein aggregates and starch-protein conjugates. Functional evaluations showed significantly higher starch solubility (<200%), improved foaming capacity (~50 % - 75%) and emulsifying properties (~9% - 33%) of the conjugates as compared to the controls, particularly at acidic pH, with notable enhancements across all pH levels (4, 7, and 10). Overall, this research demonstrated the potential of conjugating residual carbohydrate and low-value starch fractions to enhance the functional properties of pea proteins which can be used to improve the texture and stability of foams and emulsions or to improve sensory attributes in alternate meat products. The process not only adds value to starch fractions typically used for animal feed but also promotes eco-friendly, cost-effective solutions for food and beverage applications, such as alternative meats, acidic beverages, and emulsifiers.