Особливості метаболізму дріжджів при їх рециркуляції в умовах спиртової ферментації мелясного сусла

Abstract

The subject of investigation are the peculiarities of yeast metabolism of Saccharomyces cerevisiae M-5 strain in the alcoholic fermentation of molasses wort of increased concentration of dry substances in terms of periodic and continuous fermentation. For periodic alcohol fermentation of wort concentrate having 27 % dry substance content it was established, that 60g /dm³ is the optimal value for inoculate yeast. This results in the maximal accumulation of ethanol in the mature mash (11.5 vol. %), in the deep assimilation of carbohydrates and by the generation of fewer amount of glycerin. By industrial uninterrupted-mode investigations the increase in activity of starting enzymes of glycolysis and strengthening in the capacity of recirculated yeast have been demonstrated. For the first time we show, that this is a consequence of adaptation of yeast to the cultural medium as a result of long-term stay of yeast in it. The increase of the inflow speed of molasses wort into the main fermenter of the battery from 0.43 to 0.57 h⁻¹ improves physiological parameters of recirculated yeast. Also, this reduces the accumulation of secondary products of fermentation (ethers, aldehydes, higher alcohols, glycerin). At the same time, this approach allows to increase the yield of alcohol from the saccharose by 1.84 % and to enhance the productivity with respect to ethanol from 2.3 to 3.8 g/dm³ ×h.