Abstract

The article presents the results of investigating how the intensity of aerating the medium effects on the cultivation process and the metabolic activity of alcoholic yeast Saccharomyces cerevisiae, strain U-563, in the modern technology of alcohol and baking yeast from molasses. The chemical and technological parameters of media at the aerobic and anaerobic stages of the process, the level of accumulation of the major and secondary products of yeast metabolism, and their enzymatic activity have been determined by methods commonly employed in science and in the practice of alcohol biotechnology. The objects of research were the yeast Saccharomyces cerevisiae, molasses wort, the medium in the process of yeast cultivation, and fermented wash. It has been established that two factors are the most important in the accumulation of alcoholic yeast biomass: the intensity of aerating the medium, and the staged introduction of the substrate during biomass cultivation. The more aerated the medium, the more intensively secondary metabolites of yeast Saccharomyces cerevisiae are formed (glycerol, aldehydes, higher alcohols, volatile acids, and esters) – both at the yeast generation stage and during anaerobic fermentation. When yeast Saccharomyces cerevisiae is grown in a gradient-continuous manner in a battery of series-connected apparatuses, with undiluted substrate (molasses) added by degrees, yeast biosynthesis is significantly enhanced compared to the traditional homogeneous-continuous method. The results obtained indicate the active metabolism of carbohydrates in the Krebs cycle, when the medium is intensively aerated. Besides, the results reveal the high reactivity of aldehydes and esters that results in their transformation into other compounds, and in a great decrease in their amount at the anaerobic stage of the process. However, a progressive increase is observed in glycerol, higher alcohols, and volatile acids, starting from the first yeast generator and up to the last fermentation apparatus, irrespective of the level of aerating the medium during yeast cultivation. These findings can be effectively used to manufacture food, technical, and fuel ethanol industrially from sugar-based raw materials in the course of co-production of alcohol and baking yeast.

Highlights

  • Formulation of the problemThe research is in the field of biotechnology of alcohol and baking molasses yeast

  • The results indicate that the synthesis rate of these substances, when oxygen is actively introduced into the medium at the stage of yeast cultivation, significantly exceeded the rate of alcohol formation

  • The amount of aldehydes, with higher aeration of the medium during cultivation, increased to 175–204 cm3/dm3 of the alcohol formed, and decreased to 9 cm3/dm3 of anhydrous alcohol in the fermented wash (Table 3), and with a lower level of aeration, the values were, respectively, 85– 93 and 6 cm3/dm3 of anh. al. (Table 4). These values were, respectively, 6.4–11.7 and 0.75 g/dm3 of anh. al. (Table 3), and 2.2–4.8 and 0.5 g/dm3 of anh. al. (Table 4). These results indicate the active metabolism of carbohydrates in the Krebs cycle, in a medium intensively aerated, as well as high reactivity of aldehydes and esters, which results in their turning into other compounds and in a great decrease in their number at the anaerobic stage of the process

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Summary

НА МЕТАБОЛІЧНУ АКТИВНІСТЬ СПИРТОВИХ ДРІЖДЖІВ

Кафедра технології і організації ресторанного господарства Київський національний торгівельно-економічний університет, вул. У статті представлено результати досліджень впливу інтенсивності аерування середовища на процес культивування і метаболічну активність спиртових дріжджів Saccharomyces cerevisiae штаму У-563 у сучасній технології спирту і хлібопекарських дріжджів із меляси. Встановлено, що найсуттєвішу роль у накопиченні біомаси спиртових дріжджів відіграють два фактори: інтенсивність аерування середовища і ступінчатий ввід субстрату протягом процесу культивування біомаси. Із підвищенням ступеня аерування середовища посилюється утворення вторинних продуктів метаболізму дріжджів Saccharomyces cerevisiae: гліцерину, альдегідів, вищих спиртів, летких кислот і складних ефірів як на стадії дріжджегенерування, так і при анаеробному бродінні. Разом з тим встановлено поступальне збільшення гліцерину, вищих спиртів і летких кислот, починаючи від першого дріжджегенератора і до останнього бродильного апарата, незважаючи на рівень аерування середовища при культивування дріжджів. Ключові слова: градієнтно-безперервне дріжджегенерування, зброджування, дріжджі Saccharomyces cerevisiae, інтенсивність аерування, спирт, вторинні продукти метаболізму

Formulation of the problem
Analysis of recent research and publications
Research materials and methods
Results of the research and their discussion
Yeast cultivation method
The value of the parameter
Fermentation apparatus
Findings
Conclusions
Full Text
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