Sammendrag
The effect of different degrees of enzymatic cell wall disruption (45%, 70%, and 97%) of red yeast (Xanthophyllomyces dendrorhous, formerly Phaffia rhodozyma) and extruder temperatures (102, 121, and 137 °C) on astaxanthin stability and formation of astaxanthin Z-isomers was determined during extruded fish feed production. Enzymatic cell wall disruption was expressed as acetone extractable carotenoids in percent of total amount of carotenoids. The recovery of added astaxanthin in the feeds was high (range 90–99%). The recovered amount of astaxanthin during feed production was 8% higher in the diets containing red yeast with 45% enzymatic cell wall disruption than in the diets containing 97% disrupted yeast cells. Extruder temperatures in the range 102–137 °C did not significantly affect astaxanthin recovery. The proportion of astaxanthin Z-isomers of total astaxanthin increased during feed production. The proportion of all-E-astaxanthin was higher in the mash and feeds containing yeast with 45% cell wall disruption than in the ones with 70% and 97% disrupted yeast cells. Extruder temperature had little influence on the astaxanthin E/Z isomer composition. Significant interactions (P
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