Preparation of oat metal ion chelating peptides via froth floatation: Efficacy, molecular characteristics, and their anti-browning effects

Currently, the low purity and complex nature of metal ion chelating peptides (MPs) limit their application effectiveness. This study developed a novel method for the efficient preparation of MPs via zinc ion-chelating froth flotation, achieving a 19.2 % yield of high-purity MPs. The chelating capacities for Cu²⁺, Fe²⁺, and Ca²⁺ were enhanced by 22.0 %, 19.4 %, and 38.6 %, respectively. Among 414 identified peptides, amino acids with high chelating activity accounted for 66 % on average. Freshness and enzymology studies showed that MP competitively inhibit polyphenol oxidase (PPO) and peroxidase (POD), effectively reducing browning in fresh-cut apples, bananas, and red cabbage. Further research indicated that MP enter enzyme active sites, forming stable coordination with both endogenous and exogenous Cu²⁺, thereby strongly inhibiting both enzyme-catalyzed and oxidation-induced browning. This study achieved green and efficient MP preparation and pioneered their use in fruit and vegetable preservation.