Study on browning mechanism of Antarctic krill meal during storage: based on the model system approach

The non-enzymatic browning mechanism of Antarctic krill meal (AKM) during storage was undefined. To address this, different model systems with endogenous components of AKM were subjected to accelerated storage. Visual observation and colorimeter analysis indicated that lysine (Lys)/histidine (His) and phosphatidylcholine (PC)/phosphatidylethanolamine (PE) were important AKM browning substrates. Mechanistic studies further showed that both PC/PE polar heads and fatty acid tails could react with Lys/His to induce browning. Detailed analysis of PC/PE polar groups found that the browning from phosphocholine with Lys/His and phosphoethanolamine with Lys was stronger than in corresponding choline/ethanolamine systems, indicating that phosphate groups promote browning. Frontier orbital theory indicated that the phosphate group effectively reduced the binding energy of the reaction to accelerate browning. This study revealed an important pathway of browning during AKM storage, laying a theoretical foundation for developing targeted technical strategies to control AKM browning.