Monday, November 9, 2009
P25

Production of carotenoid-enriched animal feed by secondary fermentation of co-product of grain based ethanol industry

Nanjunda Swamy Ananda, Praveen Vadlani, and Ron Madl. Grain Science and Industry, Kansas State University, 1980, Kimball Ave, BIVAP Building, Manhattan, KS 66506

Whole stillage is a co-product of grain-based biofuel and is dried to produce Dried Distiller’s grain with Solubles (DDGS). Current US production of DDGS is about 10 million metric tons and is projected to increase further. DDGS is used as animal feed with scope for value addition. In general, about 30-120ppm of total carotenoids is added to animal feed to enhance meat color and quality, vitamin-A levels in milk and meat, and reproductive efficiency of animals. Since animal feed is generally poor in carotenoids, this study aimed to produce carotenoid-enriched DDGS by submerged fermentation of red yeasts. Mono and mixed culture of Phaffia rhodozyma and Sporobolomyces roseus were used to produce astaxanthin and β-carotene. Both mono and mixed culture fermentation yielded carotenoid-enriched DDGS. Total carotenoid yield from mixed culture (170µg/g) was greater than mono culture (120µg/g) fermentation. P. rhodozyma monoculture (31µg/g) produced twice the astaxanthin yield than mixed culture (14µg/g), while β-carotene yield in mixed culture (153µg/g) was similar to that of S. roseus (192µg/g) and significantly greater than that of P. rhodozyma (90µg/g) fermentation. Since the carotenoid yields are in the range that is commonly employed in animal feed, the carotenoid-enriched DDGS can be used directly as animal feed and/ or feed blends. This secondary fermentation presents an innovative strategy to utilize whole stillage and enhance market growth potential of DDGS. Fermentation optimization, effect of precursors and strain improvement will also be discussed.