EFFECT OF SODIUM SELENATE (IV) ON GROWTH AND FERMENTATION ACTIVITY OF BAKER'S YEAST

In the paper, the effect of inorganic selenium (8 mg/dm3) on the growth and rising power of baker's yeast was assessed. The yeast cultures were grown on media of molasses supplemented with a sodium selenate (IV); the samples without the selenium added were used as a reference. The baker's strains of S. cerevisiae (13/24K, R, 16/24XXX and G), originating from a collection in the Department of Spirit and Yeast Technology, Technical University of Lodz, were assessed. Compared to the cultures developed without the addition of selenium, a significant decrease in the biomass yield in the cultures with the selenium was confirmed: from 19% for the 16/24XXX strain up to 33% as for the 13/24K strain. The yeast grown on the media with the addition of selenium were characterized by a much lower rising power (the sum of three rising times is higher by 30 - 70 minutes than the normative value). The rising power of selenium yeast cultures, grown on the media with the selenium added, ranged from 156 minutes (13/24K strain) to 190 minutes (16/24XXX strain). The contents of protein, phosphorus, and mineral components in the form of ash in the yeast biomass grown on the media of molasses and supplemented with the selenium selenate (IV) were also lower than in the cultures without the addition of this compound. The 16/24XXX strain was an exception; the content levels of the three elements as mentioned above were comparable in the two cultures. The addition of sodium selenite to the culture resulted also in adverse changes in the appearance and odour of the biomass produced (dark colour and garlic - onion odour).