CAROTENOID-PIGMENTS OF THE GREEN-ALGA HAEMATOCOCCUS-PLUVIALIS - ASSAY ON RAINBOW-TROUT, ONCORHYNCHUS-MYKISS, PIGMENTATION IN COMPARISON WITH SYNTHETIC ASTAXANTHIN AND CANTHAXANTHIN

The green alga Haematococcus pluvialis was found to contain beta-carotene (2.2%), astaxanthin (free < 1%, monoester 12.4%, diester 28.8%), canthaxanthin (44.3%) and lutein (11.4%). The total amount of carotenoid was 2.0% of dry algae. Degradation of algal carotenoids occurred during the pelleting process (-3.3%) even at a low temperature (42-degrees-C), as well as during 15 days of storage at 7-degrees-C ambient temperature (-5.2%). A feeding trial was conducted to study the effects of dietary algal incorporation on muscle pigmentation of rainbow trout in comparison with synthetic astaxanthin and canthaxanthin alone or mixed (astaxanthin 48% and canthaxanthin 52%). After 4 weeks of feeding, physical colour measurements showed that increased pigmentation of the trout muscle caused an increase in chroma and a reduction in hue and lightness. Muscle of trout fed algae contained 6.2 mg carotenoid/kg versus 12.7 mg/kg for trout fed the mixture of the two synthetic carotenoids, and 11.8 and 10.1 mg/kg for trout fed synthetic astaxanthin and canthaxanthin, respectively. Carotenoid retention in the muscle of trout fed algae was 1.5% which was less than the retention of the carotenoid mixture (3.1%).