Fermentação alcoólica: contaminação bacteriana e métodos para sua detecção

Abstract

Alcoholic fermentation, carried out mainly by yeasts of the genus Saccharomyces cerevisiae, stands out for its efficiency and operational simplicity. In Brazil, sugarcane is the main raw material used, due to its high productivity and efficiency in converting fermentable sugars into ethanol and carbon dioxide. Due to the scale of production, which makes it impossible to carry out the process under aseptic conditions, the occurrence of bacterial contamination in industrial alcoholic fermentation is inevitable. Contaminating bacteria, such as those from Lactobacillus and Acetobacter genus, compete with yeasts for substrates and produce inhibitory compounds, reducing ethanol yield and increasing operating costs. Monitoring and quantifying the presence of contaminating bacteria are essential for the proper management of interventions in the process aimed at containing contamination. Traditional methods, such as direct counting under a microscope, have limitations in terms of accuracy and speed of detection. In contrast, modern techniques, such as near-infrared spectroscopy and portable sensors, offer greater accuracy and speed in fermentation monitoring. This study describes three methods for monitoring the presence of bacteria in alcoholic fermentations and analyzes the advantages and limitations of these methods in the industrial context, highlighting the importance of improving contamination monitoring techniques for the sustainability and efficiency of the sugar and ethanol sector. Different fermentation techniques, such as continuous and discontinuous processes, as well as the Melle-Boinot method, widely used for combining efficiency and economic sustainability, are addressed. Aspects such as the relevance of alcoholic fermentation in the Brazilian energy matrix, its positive environmental impact in reducing greenhouse gas emissions and its contribution to the economic and social development of rural regions are discussed. Advances in technologies, such as the production of second-generation ethanol (E2G), further expand the sustainable viability of the sugar and ethanol sector, reinforcing Brazil's strategic role in the global biofuels scenario. The study concludes that technological advances in microbiological control are essential to optimize production processes, reduce losses and meet the growing demands for sustainable biofuels.