Fermentación en estado sólido de extracto de caña de azúcar para la obtención de ácido láctico utilizando Bacillus subtilis y Streptococcus thermophilus

Abstract

This thesis project studied solid-state lactic fermentation using sugarcane bagasse as an organic substrate in the presence of lactic acid bacteria such as Streptococcus thermophilus and Bacillus subtilis. A 2³ factorial design was applied to evaluate lactic acid concentration. For B. subtilis, fermentation times of 8–10 hours, pH levels of 5–6, and temperatures of 32–37 °C were considered. For S. thermophilus, the levels were 45–50 hours, pH 5.5–6.5, and temperatures of 35–40 °C. The fermentation process was carried out under anaerobic conditions using an orbital shaker. Lactic acid characterization was performed using FT-IR, identifying its functional groups and comparing similarity with OMNIC software, yielding 71.40% with B. subtilis and 67.50% with S. thermophilus. Concentration was determined using UV-Vis spectrophotometry. It was concluded that the independent variables significantly influence the production and agglomeration of lactic acid.