Methanol present in wastewater from the biodiesel industry can become an atmospheric pollutant and an environmental liability of effluents. This article proposes the development and performance evaluation of two spectroscopic methods, ATR-FTIR and UV-Vis, to identify and quantify methanol in aqueous media. The results of both ways exhibited remarkable linear detection, with a coefficient of determination (r2) > 0.99, wide working range, and relative standard deviation (RSD) < 12%. In the ATR-FTIR method, the detection and quantification limits were 0.064 and 0.128% m V-1, respectively. The UV-Vis method presented lower limits (0.005 and 0.008% m V-1, respectively). Finally, the methods were successfully applied to quickly and sensitively quantify the methanol present in wastewater from biodiesel-washing in a wide concentration range of 0.008-0.641% m V-1. Therefore, we evidenced the feasibility of spectroscopic methods in quality control for identifying and quantifying methanol in aqueous solution, with potential for application in biodiesel production industries and research laboratories. Mainly by ATR-FTIR, in the region of 1300-900 cm-1, as it proved to be more environmentally friendly, faster, and cheaper than the GC-FID method.

RESUMO: Objetivou-se produzir vinagre, a partir da polpa de mangaba por fermentação alcoólica semi-sólida com ação enzimática através da pectinase, investigar a composição química e avaliação sensorial do produto final. O vinagre foi avaliado através da acidez volátil, extrato seco reduzido, cinzas, teor alcoólico, sulfatos, pH, compostos fenólicos totais, carotenoides totais, parâmetros de cor, rendimento, produtividade e análise sensorial. Os dados foram submetidos a estatística descritiva com média e desvio padrão. Foi aplicado a análise de componentes principais (ACP) para todas as variáveis, exceto para análise de carotenoides totais. Também foi realizada a caracterização físico-química da polpa e fermentado alcoólico. Os principais resultados mostraram que, no vinagre, extrato seco reduzido, acidez volátil, pH e cinzas foram, respectivamente, 44,3±1,5 (g/L), 4,4±0,1 (% m/v), 3,1±0,0, 3,0±0,41 (g/L). Os compostos fenólicos totais e carotenoides totais apresentaram valores de 19,2±8,20 (mg/100 g) e 2,6±0,6 (mg/100 g), respectivamente. O rendimento de conversão de etanol a ácido acético foi de 90%. ACP foi aplicada nas variáveis físico-químicas do vinagre no qual os parâmetros de cor, pH e acidez volátil apresentaram forte influência no produto e, para os atributos da análise sensorial, cor e aroma apresentaram uma forte correlação positiva entre si. O produto final atendeu a todos os quesitos legais, demonstrando ser possível a produção de vinagre de mangaba com potencial antioxidante. Na avaliação sensorial teve boa aceitação pelos provadores, valorizando o uso deste fruto do Cerrado.

ABSTRACT: The objective of this study was to produce vinegar from mangaba pulp using semi-solid alcoholic fermentation combined with the enzymatic activity of pectinase and to investigate the chemical composition and sensory characteristics of the final product. was evaluated for volatile acidity and the reduced dry extract was evaluated for ashes, alcohol content, sulfates, pH, total phenolic compounds, total carotenoids, color parameters, yield, productivity, and sensory analysis. Average and standard deviation was used for descriptive statistics. Principal component analysis (PCA) was applied to all variables except total carotenoid content. Physicochemical characterization of the raw and alcoholically fermented pulp was also carried out. The main results showed that, in the vinegar, the reduced dry extract, volatile acidity, pH, and ashes were 44.3±1.5 (g/L), 4.4±0.1 (% w/v), 3.1±0.0, and 3.0±0.41 (g/L), respectively. The total phenolic compound content and total carotenoid content for the mangaba vinegar were 19.2±8.20. mg/100 g and 2.6±0.6. mg/100 g, respectively. The conversion yield from ethanol to acetic acid was 90%. PCA showed that pH and volatile acidity had a strong influence on the product, and there was a strong positive correlation between color and aroma. The final product met all legal requirements, showing that it is possible to produce mangaba vinegar with antioxidant potential for consumers. In the sensory evaluation, it was favored by the tasters, demonstrating potential economic value in the Cerrado fruit.