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Carotenoid Value Addition of Cereal Products by Monoculture and Mixed-Culture Fermentation of Phaffia rhodozyma and Sporobolomyces roseus

¹Bioprocessing and Industrial Value Added Program (BIVAP), Department of Grain Science and Industry, Kansas State University. ²Corresponding author. 301 Goodwyn Hall, 7061 Senators Dr., Department of Biology, Auburn University, Montgomery, AL 36117. Tel: 334-244-3625. Fax: 334-244-3993. E-mail: ananjund@aum.edu

Carotenoid value addition of corn whole stillage by red yeast fermentation has yielded astaxanthin- and β-carotene-enriched distillers dried grains with solubles (DDGS) for animal feed. In this study, commonly used animal feeds (rice bran, wheat bran, milo whole stillage, and soybean products) were subjected to carotenoid value addition. Phaffia rhodozyma and Sporobolomyces roseus monoculture and mixed-culture submerged fermentation of these substrates supplemented with 5% glycerol were analyzed for astaxanthin, β-carotene, and residual glycerol. Among all the substrates, full-fat rice bran and full-fat soy flour resulted in the highest astaxanthin (80 μg/g by P. rhodozyma) and β-carotene yields (836 μg/g by S. roseus). P. rhodozyma produced the highest astaxanthin yield on each substrate, whereas depending on the substrate, either the mixed culture or S. roseus monoculture produced the highest β-carotene yield. Soy hull was a poor substrate for carotenoid value addition. Both yeasts used glycerol as a carbon source for carotenoid production. This study shows that substrates influence the carotenoid yield. However, it is impossible to dissect the effect of specific nutrients on carotenoid production in complex biological substrates. Carotenoid value addition of these substrates provides as much as or more than the required daily dosage of carotenoids in animal feed.