Study On Preparation Of Chromium-enriched Yeast By Discarded Brewers Yeast

Through adding inorganic chromium (CrCl₃·6H₂O) into the culture medium, chromium-enriched yeast was produced by means of shaking culture. Each kind of influence factors on preparation of chromium-enriched yeast ( kind of culture medium, concentration of chromium ion, initial pH of culture medium, cultivate time, yeast adding quantity, cultivate temperature)are studied.According to the result of single factor test, an orthogonal experiment (four factors and three level) was designed, The studied factors are concentration of chromium ion, cultivate time, initial pH of culture medium and yeast adding quantity. The optimum condition is as follows: The wort is chose as culture medium, cultivate temperature is 28℃, The concentration of chromium ion is 600μg/mL, initial pH of culture medium is 4.0 4.5, cultivate time is 18h, yeast adding quantity is 50g/50mL culture medium.In order to find out the chromium-enriched mechanism, the chromium-enriched yeast and blank yeast were analyzed by infrared spectrum (IR). It is showed that there are two changes in the IR. The first one is that max absorption peak of hydroxyl shifts from 3317cm^-1 to 3296cm^-1. Maybe the hydroxyl involve enrich of chromium. The second one is that max absorption peak of amide (II) shifts from 1545cm^-1 to 1538cm^-1. Maybe some protein in the yeast involve enrich of chromium.The amide acid analysis shows the content of amino acids in chromium enriched yeast was higher than that of general yeast, especially the contents of necessary amino acids, such as lysine, methionine, leucine, isoleucine.Animal experiment shows apparent digestive absorptivity of rat is 89.03%. The digestive absorptivity of chromium enriched yeast, which is organic, by rat is higher than that of inorganic salt.