Purificação do caldo de cana-de-açúcar por irradiação ultravioleta e micro-ondas para produção de açúcar e etanol

Abstract

The process of clarification of sugarcane juice during the production of sugar is carried out with one or more chemical agents such as milk of lime and sulfur dioxide; involves heating, decanting and vacuum filtration of the residue decanted. New technologies for separation and purification that reduce energy cost and production or reduce harmful effects on the environment are highlighted in recent years. The use of non-thermal irradiation technologies such as ultraviolet and microwave, may simplify the process of juice clarification of sugarcane, since it does not input and uses can be automated, rationalizing the manpower and lowering the cost of production, besides having shown to be effective in reducing microorganisms contained in food and also modify color and turbidity of juices. Thus, the aim of this study was to purify the sugarcane juice by ultraviolet radiation and microwave radiation to produce sugar and ethanol. In the laboratory experiment, comparisons were made of the physical and chemical analysis of the in natura juice with the juice obtained after treatment by irradiation. As regards the purified material were analyzed turbidity, color, soluble solids content (°Brix) and pH, and microbiological analyzes. With respect to count microorganisms used the pour-plate method and spread-plate for bacteria and fungi to spread-plate. For data analysis was utilized analysis of variance - ANOVA - followed by Tukey test and/or the nonparametric Kruskal-Wallis test, followed by multiple comparisons by orders, each with significance level 0.05. The microwave method with power 600 W and exposure time was 2 min as indicated where there was no significant variation in color, turbidity and ° Brix, pH was significantly decreased, no contamination by fungi and aerobic bacteria and with respect the facultative bacteria was contamination but without statistical significance. For the ultraviolet method, the power of 250 W and an exposure time of 3 min is the most adequate, where variations in the ° Brix and pH were not significant, color and turbidity show a significant reduction, no fungal contamination and the treatment reduced the number of colonies of aerobic and facultative bacteria. With this, it is proposed that change in the production of sugar and ethanol production process by eliminating steps sulfitation, liming, heating and decanting to ultraviolet.