Abstract:

In this paper, the extraction and separation of glutathione (GSH) and wheat germ protein from defatted wheat germ was investigated. Glutathione was extracted from defatted wheat germ under the low pH condition. Glutathione and wheat germ protein in extract were separated by ultra-filtration method. The protein residue after GSH extraction was subjected to further alkali extraction. The obtained protein was purified by isoelectric precipitation method. The extraction conditions for GSH were optimized by single factor and orthogonal experiments to be material-liquid ratio of 1:13, pH of 6.3, extraction temperature of 55 ℃ and extraction time of 15 min. Under the optimal extraction conditions, the yield and extraction rate of GSH was up to 0.31% and 72.1%. The extraction conditions for wheat germ protein were optimized by single factor and orthogonal experiments to be material-liquid ratio of 1:11, pH of 10.5, extraction temperature of 65 ℃ and extraction time of 60 min. Under the optimal extraction conditions, the yield and extraction rate of protein was up to 39.2% and 90.4% based on the amount of alkali extraction precipitate. The yield and extraction rate of protein were 20.8% and 58.8% based on the amount of defatted wheat germ. The ultra-filtration liquid and supernatant after alkali precipitation was combined. The optimum pH for precipitating protein from combined solution was 4.2. The precipitation rate and yield of protein were 97.5% and 85.2%. After the combination, the extraction rate of protein was 81.1% based on the amount of deffated wheat germ.

Key words: defatted wheat germ, reduced glutathione, wheat germ protein, extraction, isoelectric precipitation