Use of Heat to Saponify Xanthophyll Esters and Speed Analysis for Carotenoids in Feed Materials: Collaborative Study

Abstract

Abstract Twelve collaborators analyzed 4 pairs of samples to compare a 20 min hot (56°C) saponification technique with the overnight extraction technique at room temperature in the official first action method for analysis of carotenoids in feed materials, 39.018–39.023, with a view to (a) make the method applicable to products which contain xanthophyll esters and (b) speed up the analysis. In general, the collaborators were in good agreement, with saponification of esters essentially complete after the 20 min heating of samples that contained marigold meal. While the sum of extracted pigments from corn gluten and alfalfa meal tended to be slightly higher with the longer (overnight) contact with the solvent than with the hot extraction, the differences were not statistically significant. Significant differences between hot and cold treatments were absent also in alfalfa pigment fractions, but hot saponification significantly lowered monohydroxy pigments and increased dihydroxy pigments in extracts from corn gluten. The results showed good precision with either extraction technique. The method, modified to include hot saponification as an alternative step, is now applicable to all dried feed materials, including those which contain xanthophyll esters (e.g., marigold meal); the modification has been incorporated into the official first action method, 39.018–39.023.