Harčova Nauka ì Tehnologìâ (Mar 2021)
THE COMPARATIVE STUDY ON TWO COMMERCIAL STRAINS OF SACCHAROMYCES CEREVISIAE FOR ETHANOL PRODUCTION FROM HARD-TO-FERMENT SUGAR-CONTAINING RAW MATERIALS
Abstract
The growth of bioethanol production is relevant to Ukraine both for environmental and economic reasons. Effective measures to reduce the cost of bioethanol production from sugar-containing raw materials, in particular sugar beet molasses, are the use of high gravity wort and osmotolerant yeasts strains. Prolonged exposure to high temperatures during the process of sugar production and changes in composition during storage contribute to the accumulation of compounds in molasses that have a negative effect on the function of the yeasts cells. For such type of raw material, it is advisable to determine a strain of yeasts that will withstand not only a high concentration of sugars or the final product, but will also be more resistant to inhibitors. The use of two industrial yeasts strains (Deltaferm® AL-18 and Y 5007 (K-7)) for molasses wort fermentation was investigated. It was determined that sugar beet molasses, which is considered hard-to-ferment, can be used in ethanol production with high gravity wort, if some correction measures are taken, particularly the usage of resistant producent strains. It was found that Deltaferm® AL-18 yeasts are characterised by longer lag-phase and reach the 50-60% carbohydrates consumption level 24 hours later comparing to Y 5007 (К-7) yeasts strain. The changes in fermented wort parameters obtained during fermentation of high gravity wort based on hard-to-ferment molasses by different yeast strains were defined. It was investigated that during the usage of high gravity wort obtained from low quality molasses, yeast strain of foreign selection does not reach the calculated alcohol content in mature wort. According to the results of research alcohol yeasts Y 5007 (К-7) under the same fermentation conditions more efficiently ferment high gravity wort based on hard-to-ferment molasses and their use in industrial conditions according to the classic two-stream fermentation scheme in comparison with dry yeast does not require additional investments.
