The degree of carotenoid esterification influences the absorption of astaxanthin in rainbow trout, Oncorhynchus mykiss (Walbaum)

The absorption of astaxanthin from diets (30 mg kg−1 inclusion) supplemented with either unesterified astaxanthin; isolated astaxanthin monoesters, diesters or a cell-free carotenoid extract from Haematococcus pluvialis were studied in rainbow trout (>200 g). No significant differences (P > 0.05) were recorded in the apparent digestibility coefficients (ADC) (≈60–65%) between astaxanthin sources. However, following consumption of a single meal, peak serum astaxanthin levels at 32 h (≈1.0–1.6 μg mL−1) were significantly higher (P < 0.05) in fish fed unesterified astaxanthin and astaxanthin monoester, compared to fish fed astaxanthin diester and the cell free extract. However, no significant differences (P > 0.05) were recorded in serum astaxanthin uptake rates between sources of astaxanthin. Results suggest that the extent of carotenoid esterification negatively influences the peak serum levels of astaxanthin in rainbow trout.