Reduction of carotenoids in corn gluten meal with soy flour

Corn gluten meal (CGM) is an abundant byproduct of the wet yellow corn mill ing process. Undesirable colored flesh is obtained when CGM is fed to fish with white flesh; therefore, the removal of the carotenoids, the color pigm ent in CGM, is desired. Carotenoids in corn gluten meal were reduced by ble aching with soy flour as a lipoxygenase source at a 5% substitution level a t different experimental scales. A completely randomized design was used wi th one treatment to determine effects of pH, enzyme activity, and spray-dry ing temperature and with combinations of two treatments to determine effect s of experimental scale, stirring method, and reaction time. The optimum pH of the slurry was 6.5 at the 20-g experimental scale. The optimum reaction time to reach the maximum bleaching increased as the experimental scale in creased. More vigorous stirring shortened the optimum reaction time where m aximum bleaching occurred and improved the degree of bleaching to same exte nt. At the 250-g experimental scale, 70% of the carotenoids in CGM were ble ached when the reaction was carried out at pH 6.5 for 60 min with vigorous stirring using a homogenizer As drying temperature increased from 160 to 25 0 degreesC, carotenoids were reduced by an additional 9.4 to 26.4%. These r esults indicated that the optimum pH for the reaction medium is 6.5 and mor e carotenoids in the CGM can be bleached faster with soy flour at a plant s cale using a more vigorous stirring method.