Cysteine content obtained from the variation of temperature and acidity on soybean extraction

Modifying the Saccharomyces cerevisiae culture medium with cysteine supplementation is an effort to increase the production of glutathione. Soybeans contain high cysteine, where its extract has potential value as enrichment media for S. cerevisiae to glutathione synthesis. Soybeans that used in this study were local varieties of Grobogan Central Java. This study aimed to analyze the effects of temperature, pH, and the drying process of soybeans extraction, and to obtain high content of cysteine in soybean extract. Soybeans were extracted using acetic acid in pH 4.0; 4.5; and 5.0 at room temperature and 50? C. Pellets obtained were dried using freeze dryer or heat dryer. The result showed that the highest cysteine content at 7.4 mg/g was derived from soybean extraction at pH 5.0, room temperature, and heat dryer. Therefore, by combining the pH and the incubation temperature during the extraction process can be suggested to increase the cysteine levels in soybean extract, especially for local varieties of Grobogan Central Java.