Inhibitory kinetics and antioxidant efficiency of kiwicha (Amaranthus caudatus L.) protein hydrolysates for preserving minimally processed Potato (Solanum tuberosum) and yacon (Smallanthus sonchifolius)

Kiwicha ( Amaranthus caudatus ) proteins are a promising source of bioactive peptides with antioxidant and anti-browning potential. This study evaluated the functional properties of amaranth protein fractions and hydrolysates and their effects on polyphenol oxidase (PPO) inhibition, antioxidant activity, color preservation, and mass stability in minimally processed potato (Blanca and Canchan cultivars) and yacon cubes. Protein content was determined by the Bradford method, peptide profiles were characterized by SDS-PAGE, antioxidant capacity was assessed using DPPH, ABTS, and FRAP assays, and PPO inhibition kinetics were evaluated. Multivariate relationships among biochemical, kinetic, and physicochemical variables were explored through principal component analysis (PCA). The results showed significant differences among treatments in antioxidant activity, PPO inhibition, color preservation, and mass retention. Several hydrolysates exhibited strong inhibitory effects against PPO and contributed to the maintenance of quality attributes during storage. Antioxidant activity was positively associated with total polyphenol content, while PCA revealed relationships among protein composition, antioxidant properties, enzymatic inhibition, and color parameters. Overall, amaranth-derived hydrolysates demonstrated potential as natural antioxidant and anti-browning agents for minimally processed plant products. Their effectiveness depended on both hydrolysate characteristics and the plant matrix evaluated, highlighting their potential application in sustainable food preservation systems.