Analysis of fermentative parameters and the importance of Saccharomyces cerevisiae in the development of goods and services

In the fermentation process, yeasts need to adapt to the environmental changes that occur during the production process. Responses to these adjustments can alter biochemical routes and the amount of metabolites produced. Thus, the objective was to analyze the fermentative parameters of industrial yeast strains in different growing conditions, as well as to evaluate the its applicability in different sectors of goods and services. A pre-inoculum was performed with the YPSAC 5% medium for the activation of the yeasts Catanduva-1 and Fleischmann that remained incubated for 24 hours at 30 °C at 250 rpm. After the cells were recovered by centrifugation and inoculated in the fermentation medium based on sugarcane juice at 15 °Brix at temperatures of 30 and 40 °C. Aliquots were removed for the analysis of the fermentative parameters. Concomitantly, a survey was carried out regarding the use of yeasts in the process of preparing goods and services. The data show that the best yeast fermentation performance occurred at 30 °C in 10 hours. In addition, yeasts have the ability to produce, under ideal conditions, metabolites that can be used in different biotechnological processes.


Introduction
The fermentation process uses selected yeast strains resulting in significant gains in productivity and efficiency, due to the characteristics of the microorganisms such as fermentation stresses tolerance, ability of deployment in distillery and stoichiometry favorable to high ethanol production (Basso et al., 2008). It may also be benefited by other technological advances such as the fermentation with high sugar content, resulting in economic, social and environmental benefits (Basso et al., 2011).
Thus, changes in the profile of intracellular metabolites produced by Saccharomyces cerevisiae Meyen ex EC Hansen may occur, which may be related to adaptive mechanisms that admit that they provide yeast cells with better adaptation and survival in the face of stress factors present in the fermentation process (Pereira et al., 2011). In addition, according to Santos et al., (2010), such metabolites are considered substrates for fermentation and may be dispersed in the medium or accumulated inside the yeasts. Thus, strains that are capable of fermenting in media with a high concentration of sugars accumulate high concentrations of metabolites (Barbosa, 2013).
In the last decade, research on the use of these yeasts in relation to molecular and genetic modifications has been intensified for the efficient and viable production of ethanol using five-carbon sugars as a substrate (Pereira et al., 2011;Zhang et al., 2015), in addition to several other processes such as the production of vitamins, proteins, enzymes, heterologous proteins and in products of pharmaceutical interest through manipulation with new metabolic pathways that are possible through genetic improvements, since its genome has already been completely sequenced (Badotti et al., 2008).
Some strains can also be used as raw material converters in the processes of obtaining biofuels, in addition to other applications such as the production of secondary compounds with a focus on biorefineries. Still in the area of metabolites, there is the prospecting of yeasts and the study of physiological routes for the production of different compounds that can be used in different biotechnological processes.
However, as yeasts are considered an essential component of fermentation processes, it is necessary to understand the fermentative performance in relation to temperature and the prolonged fermentation time to better understand the different physiological mechanisms of these microorganisms. Thus, the objective was to analyze the fermentative parameters of industrial yeast strains in different cultivation conditions, as well as to evaluate the applicability of this microorganism in different sectors of goods and services. Research, Society and Development, v. 9, n. 11, e93691110586, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i11.10586

Results and Discussion
The study of fermentative parameters in industrial yeasts grown in must based on sugarcane juice is extremely important. Such parameters can be monitored during the fermentation process allowing a greater production of ethanol. In the analysis of the fermentation parameters of industrial yeasts grown based on sugarcane juice at a concentration of 15 ⁰Brix, at a temperature of 30 ⁰C, and different fermentation times are shown in Table 1.
It was observed that the yeast Fleischmann showed a viability rate of 77% in 10 hours of fermentation. The yeast Catanduva-1 showed an index of living cells in this fermentation period of 90%, showing that it is more adapted to the industrial fermentation process.
However, in the longer periods, 20 and 40 hours, there was a sharp drop in the rate of living cells for both yeasts. In the evaluation of biomass production at 30 ⁰C, the best performance was in the time of 20 hours of fermentation for both strains analyzed (Table 1).
At 40 ⁰C there was a retraction of the values of the biomass and viability fermentative parameters demonstrating that the temperature and the prolonged fermentation time acted as stress factors in the yeast physiology. However, the yeast Catanduva-1 was more resistant to these disorders, since there was a small change in the accumulation of glycerol by this strain.
In this study, it can be seen that the total residual sugar was considerably high for both strains in the 10 hour time, decreasing in the subsequent times. The analysis of the quantification of glycerol showed that there was no variation in the production of this metabolite as shown in Table 1.
Yeasts adapted to the industrial process respond efficiently when exposed to ideal fermentation conditions, such as a temperature of 30 °C, considered ideal for maintaining their physiological pathways. Fermentation time is also considered by some authors as a stress factor, as there may be an accumulation of ethanol in the fermentation medium causing Research, Society and Development, v. 9, n. 11, e93691110586, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i11.10586 6 changes in the metabolic routes and even in cell viability. Exposure of yeast cells to high temperatures causes increased membrane permeability, while lower temperatures result in decreased permeability (Fairbairn, 2012). The rate of cell