Abstract:

In order to improve the utilization of corn gluten meal (CGM), the alcalase hydrolysis process of the material for the extraction of xanthophylls and zeaxanthin and the high speed counter current chromatographic (HSCCC) separation of xanthophylls and zeaxanthin from the residue left after alcalase hydrolysis were explored. The effects of pH, temperature, enzyme loading, substrate concentration and hydrolysis duration on the extraction efficiency of xanthophylls were examined. The results showed that the extraction efficiency of xanthophylls was increased significantly by enzyme treatment when compared with the traditional solvent extraction method (P ＜ 0.05). Considering extraction efficiency, production cost and experimental feasibility, the optimum conditions for CGM hydrolysis were determined to be: pH 7.0, reaction temperature 40 ℃, enzyme loading 4000 U/g, substrate concentration 110 g/L and hydrolysis duration 2 h. Under these optimum conditions, the extraction efficiency of xanthophylls was 59.57μg/g. The binary phase system employed for the preparative HSCCC purification of the crude extract was composed of n-hexane, ethyl acetate, ethanol and water (4:1:4:1, V/V). HPLC determination revealed that the purities of the trans-xanthophylls and the trans-zeaxanthin were 90.85% and 91.21%, respectively. Preparative HSCCC could not thoroughly separate the trans and cis isomers of xanthophylls and zeaxanthin, although the technique succeeded in separating the two compounds.

Key words: corn gluten meal, xanthophylls, extraction, alcalase hydrolysis, HSCCC, purification