Mechanisms underlying astaxanthin alterations during on-site processing of Antarctic krill (Euphausia superba)

Abstract

Astaxanthin is a crucial natural carotenoid present in Antarctic krill (Euphausia superba); however, there are no reports of possible compositional changes in Antarctic krill during on-site processing in Antarctica. In this study, Antarctic krill underwent serious color deterioration during cold storage, accompanied by an overall upward trend in its total carotenoids, thiobarbituric acid reactive substance (TBARS) value and lipid oxidation (LPO). The texture profile also changed significantly: softer texture, reduced elasticity, decreased chewiness and cohesiveness. Asta-C16:0, Asta-C18:1, Asta-C14:0, Asta-C20:5, Asta-C14:0/C14:0, Asta-C14:0/C16:0, Asta-C16:0/C16:0 and Asta-C16:0/C18:1 were found in astaxanthin monoesters and diesters. Overall, the arrangement of the contents of astaxanthin molecules in Antarctic krill was largely consistent with previous literatures. Additionally, Asta-C18:1/C18:4 was not detected in any of the samples, a discrepancy potentially linked to seasonal variations across studies. Transcriptome analysis revealed that differentially expressed genes (DEGs) related to protein hydrolysis and oxidative stress were identified through metabolic pathway enrichment analysis. Molecular docking suggested that pancreatic lipase likely plays a key role in astaxanthin degradation triggered by the strong autolysis environment of Antarctic krill. This research provides a basis for further avoiding the degradation and efficient utilization of astaxanthin in Antarctic krill during the processing and storage.