Preparation of Fish Feed Ingredients: Reduction of Carotenoids in Corn Gluten Meal

Abstract

Carotenoids in corn gluten meal (CGM) were eliminated by extraction with ethanol and butanol or by bleaching with soy flour as a lipoxygenase source. Corn gluten meal (50 g at 67% moisture basis) was extracted with 150 mL of ethanol or butanol followed by a second extraction with 100 mL of extractant. Of the carotenoids present in CGM, 87% and 94% were removed after the second extraction with ethanol and butanol, respectively. Total solid loss during extraction was greater with butanol (24%) than with ethanol (10%). Increasing the level of soy flour substituted from 5% to 15% did not improve the degree of bleaching but shortened the time to reach the maximum degree of bleaching at which 51% of carotenoids were bleached. Incorporating 5% soy flour, presoaking of soy flour, and aerating of the reaction medium reduced the reaction time to 30 min. The bleached and heat-dried product contained 62% less carotenoids compared with its unbleached counterpart. Keywords: Corn gluten meal; fish feed; carotenoids