Molecular Composition, Digestion and Absorption Characteristics of Astaxanthin in Antarctic Krill Oil

The extraction of Antarctic krill oil enrich astaxanthins using n-hexane-ethanol solvent systems was studied, taking the total astaxanthin content, phospholipid content and yield of Antarctic krill oil as the investigation indexes. Meanwhile, the molecular species composition of astaxanthins in Antarctic krill oil which extracted under the optimized conditions were characterized and analyzed. Then the digestion process and bioaccessibility of astaxanthins in Antarctic krill oil were investigated by single-dose oral gavage with different doses of Antarctic krill oil, using ICR mice as model animals. Furthermore, the bioacceptability of astaxanthin from Antarctic krill oil and Haematococcus pluvialis were compared. The results showed that the 60%(V/V) n-hexane-ethanol solution was selected as the best solvent to extract Antarctic krill oil enrich astaxanthins. The astaxanthins in krill oil were mainly present as fatty acid esters, the relative percentages of astaxanthin diesters, monoesters, and free astaxanthin were 73.5%, 24.8%, and 1.62%. The astaxanthin diesters were hydrolyzed to monoesters or free from in the gastrointestinal tract. After 24 hours of gavage, the bioaccessibility of astaxanthin in low, middle and high dose groups was not significant, and the bioaccessibility of astaxanthin in Antarctic krill oil was about 74%. In addition, the bioaccessibility of astaxanthin in Antarctic krill oil was about 1.25 times of that in Haematococcus pluvialis oil. These results could provide a scientific basis for the rational production and the evaluation of dietary nutritional of Antarctic krill oil.