CHARACTERIZATION OF NUTRIENTS IN CAROTENOID-ENRICHED FULL FAT SOY FLOUR AND RICE BRAN PRODUCED BY RED YEAST FERMENTATION

Abstract

Carotenoids are used as feed additives for improved animal health and to produce quality animal products. Fermentation of corn whole stillage, rice bran, soybean flour etc by carotenogenic or red yeasts can result in carotenoid-enriched animal feed. Usually, the prescribed dietary dosage of carotenoids like astaxanthin and β-carotene is 1-120μg/g feed. In a previous study, Phaffia rhodozyma-fermented full fat rice bran and Sporobolomyces roseus-fermented full fat soy flour resulted in highest astaxanthin yield of 80μg/g feed and β-carotene of 836μg/g feed respectively. The aim of this study was to qualitatively and/or quantitatively evaluate the nutrition profiles of these two fermented products. In both products, there was reduction in crude fiber, crude protein and amino acids whereas the crude fat content was enhanced in rice bran and reduced in soy flour respectively;  the levels of some amino acids like hydroxyproline, hydroxylysine and ornithine were enhanced; oleic acid increased by 83% in S. rosues-fermented soy flour whereas stearic acid was enhanced by 389% in P. rhodozyma-fermented rice bran; and trypsin inhibitor was reduced to undetectable levels in carotenoid-enriched soy flour. Both fermented substrates contained 1 to 3% glucans and, 2.4 to 5.7% mannans, and glucosamine ranging from 0.13 to 4.6%. In addition to high levels of carotenoids, red yeast fermentation of both soy flour and rice bran yielded a suite of nutrients and the final product could be used to make ‘feed blends’ to provide adequate nutrients based on the dietary requirements of the animals.