Pigmentation and Composition of Flesh of Atlantic Salmon Fed Diets Supplemented with the Yeast Phaffia rhodozyma

Abstract

In a pigmentation trial, Atlantic salmon Salmo salar in ocean pens were fed diets supplemented with the red yeast Phaffia rhodozyma, a control diet supplemented with synthetic astaxanthin, and a nonpigmented control diet. Yeast diets contained spray-dried untreated P. rhodozyma, heat-treated and spray-dried P. rhodozyma, and heat-treated and chemically treated spray-dried P. rhodozyma. Growth, weight, and fork length of all fish increased linearly with feeding and were not significantly different at the end of the study. Astaxanthin concentration in all pigmented fish increased linearly and ranged from 3.26 to 3.78 mg/kg after 150 d of feeding. Apart from the nonpigmented diet, astaxanthin concentration was not significantly different between fish fed the untreated or treated red yeast and those fed the synthetic astaxanthin diet (control). Assessment of astaxanthin isomers corroborated the assimilation of the (3R,3′R) isomer from all P. rhodozyma diets. Moisture, ash, and protein in all fish declined linearly with time, whereas lipid increased, but only during the first 30 d of feeding. Fatty acid profiles of all fish were virtually identical and independent of the source of pigment. No beneficial or adverse nutritional effects to the fish resulted from the use of modified red yeast.

Notes

¹ Ratio is the number of carbon atoms to the number of double bonds, and n designates the position of the first double bond from the methyl end.