An Integrated Autolysis Process Utilizing Endogenous Enzymes for Enhanced Astaxanthin Extraction and De‐Esterification From Antarctic Krill

Natural astaxanthin is a high-value carotenoid abundantly found in Antarctic krill, the efficient extraction and bioactivity enhancement of natural astaxanthin are of significant importance for its application in nutraceuticals and functional foods. However, this process faces dual challenges: the robust structural matrix of krill impedes solvent penetration, and astaxanthin predominantly exists in esterified forms with lower bioavailability. To address this, we developed an integrated autolysis process that utilizes the krill's own endogenous enzymes (proteases, lipases, and chitinases) for simultaneous matrix disruption and astaxanthin de-esterification. Compared to conventional methods that rely on exogenous enzymes or chemicals, our approach offers distinct advantages: it is environmentally benign, cost-effective, and enables simultaneous matrix disruption and astaxanthin de-esterification in a single step. Through experimental design, the optimal autolysis conditions were identified as pH 7.5, 60 ℃C, and 2 h. Under these optimized conditions, the process achieved three key outcomes: (1) An astaxanthin yield of 91.18 µg/g was achieved, representing a significant increase compared to conventional extraction methods; (2) A protein hydrolysate was simultaneously produced, with its proportion of essential amino acids substantially elevated from 12.276 ± 0.013 to 34.368 ± 0.042 mg/100 g, thereby significantly enhancing its nutritional value; (3) Effective de-esterification raised the proportion of free astaxanthin from 18.11% to 30.50%. The resulting extract demonstrated superior antioxidant activity, which was positively correlated with its free astaxanthin content. This green and cost-effective strategy represents a promising approach for the comprehensive, high-value utilization of Antarctic krill biomass in nutraceutical and functional food applications.