Resumo A caleagem [adição de Ca(OH)2] e a sulfitação (adição de HSO3-) são etapas do tratamento convencional do caldo de cana (CCA) em usinas para a produção de açúcar cristal. Embora a geração de sulfito esteja associada a problemas de saúde humana, essa etapa industrial manteve-se intocável, sendo que poucos estudos foram feitos para alterar esse cenário. Este trabalho teve como objetivo avaliar as variáveis que influenciam o desempenho da eletrocoagulação na purificação de CCA como um processo alternativo à produção de açúcar cristal sem uso de enxofre. Um planejamento fatorial fracionário com a metodologia de resposta de superfície foi utilizado para avaliar a influência da tensão, do pH, dos sólidos solúveis totais (Brix), da temperatura e da distância entre os eletrodos no processo de eletrocoagulação do caldo de cana. As respostas avaliadas foram turbidez, cor do caldo, teor aparente de sacarose (como pol%caldo) e açúcares redutores (AR). O alumínio residual foi analisado por voltametria, para avaliar a liberação de alumínio no caldo tratado. A eletrocoagulação reduziu a cor e a turbidez, em especial em pH baixo (=2,5), tensão mais alta (=25 V) e distância mínima do eletrodo (=1,0 cm). Verificou-se, contudo, que, nessas condições, a sacarose foi parcialmente convertida em AR, indicando hidrólise. Neste trabalho, a maior parte do alumínio residual foi para as fases flotada e precipitada (76,8% e 18,1%, respectivamente), enquanto apenas 5,1% permaneceram no CCA clarificado. A eletrocoagulação/eletroflotação mostrou-se uma técnica potencial como substituto à sulfitação no tratamento de CCA, o que garante a produção de alimentos seguros para a população.

Abstract The liming (Ca(OH)2 addition) and sulfitation (HSO3- addition) is the conventional treatment for purification of sugarcane juice (SCJ) in sugar cane mills to crystal sugar production. Although, the sulfite has been associated to human health problems, this industrial step kept untouchable or few studies have been made to change this scenery. This work aimed to evaluate the variables which influence the electrocoagulation performance on the SCJ purification as a sulfur-free crystal sugar process. A fractional factorial design with the surface response methodology was used to evaluate the influence of voltage, pH, soluble solids total (Brix), temperature and distance between the electrodes in the electrocoagulation process. The outputs were turbidity, juice color, sucrose contents (as pol%juice) and Reducing Sugars (RS). Residual aluminum was analyzed by voltammetry to control de aluminum releasing into the treated juice. The electrocoagulation reduced color and turbidity, in special at low pH (2.5), highest voltage (25 V) and minimal distance of electrode (1.0 cm). Although in this conditions, sucrose was converted into RS indicating partial hydrolysis. In this work, the most part of residual aluminum went to floated and precipitated phases (76.8% and 18.1%, respectively), whereas only 5.1% remained in the SCJ clarified. Electrocoagulation/electroflotation proved to be a potential technique as a substitute for sulfitation in SJC treatment, which ensures the production of safe food for humans.

Resumo Uma solução comercial de H2O2 (35%, v/v) foi avaliada como agente clarificante em xarope de açúcar tipo VHP (alta polarização), em arranjo experimental de redes neurais artificiais (RNA). Quinze corridas experimentais foram conduzidas e as amostras foram coletadas em intervalos de tempo de 0, 5, 10, 15, 20, 25, 30, 40, 50, 60, 75 e 90 min. Os ensaios foram conduzidos usando um arranjo experimental composto por três variáveis, sendo: H2O2 (X1: 0; 202,4; 500; 797,6 e 1.000 mg L-1); pH (X2: 3,32; 5; 7,5; 10 e 11,68), e temperatura (X3: 16,4; 30; 50; 70 e 83,6°C). Os valores teóricos e mensurados se encaixam bem na análise por RNA. Observou-se redução da coloração entre 60 e 75 min, com exceção dos tratamentos #11 (pH= 11,68; 50°C e 500 mgH2O2 L-1), #13 (pH=7,5; 83,6°C e 500 mgH2O2 L-1) e #15 (pH= 7,5; 50°C e 1.000 mgH2O2 L-1), que apresentaram redução de cor após 30 min. No tratamento com pH 3,32 ou 11,68, temperatura 83,6°C e dose de H2O2 de 1.000 mg L-1, observou-se uma degradação da sacarose de 55%, em média. No tratamento # 9 (pH 7,5, 50°C e 500 mgH2O2 L-1), obteve-se o melhor resultado para a redução de cor, embora tenha sido percebida 26% de degradação de sacarose.

Abstract A commercial H2O2 solution (35%, v/v) was evaluated as a clarifying agent for raw, type VHP (very high polarization) sugar syrup, using an experimental design applying artificial neural networks (ANN). Fifteen experimental runs were carried out and the samples were taken at the following time intervals: 0, 5, 10, 15, 20, 25, 30, 40, 50, 60, 75 and 90 min. The treatments were carried out using an experimental design consisting of three variables: H2O2 (X1: 0; 202.4; 500; 797.6 and 1.000 mg L-1); pH (X2: 3.32, 5, 7.5, 10 and 11.68) and temperature (X3: 16.4, 30, 50, 70 and 83.6°C). The theoretical and measured values fitted the analysis by artificial neural networks (ANN) well. A reduction in colour (ICUMSA method) was observed between 60 and 75 min, except for treatments # 11 (pH= 11.68; 50°C and 500 mgH2O2 L-1), # 13 (pH=7.5; 83.6°C and 500 mgH2O2 L-1) and #15 (pH= 7.5; 50°C and 1.000 mgH2O2 L-1), which showed a colour reduction after 30 min. In the treatments at pH 3.32 or 11.68, temperature of 83.6°C and H2O2 dose of 1.000 mg L-1, an average sucrose degradation of 55% was observed. The best colour reduction result was obtained with treatment # 9 (pH 7.5, 50 °C and 500 mgH2O2 L-1), although sucrose degradation of 26% was observed.

Abstract The objective of this study was to characterize jabuticaba fruits for their proximate composition, minerals profile, and predominant sugars during fruit physiological development. The fruits were harvested ten days after anthesis (DAA) until maturity, at intervals of four days between collections. The period between anthesis and maturity was 34 days. An increase in moisture was observed, as for protein and lipids up to 18 DAA, with subsequent reduction until ripening, while an opposite behavior was observed for ash and carbohydrates levels. In general, minerals decreased throughout the fruit development. Regarding the carbohydrates profile, fructose showed the highest concentration, followed by glucose and sucrose, respectively, with an increase during ripening for all sugars. Whereas the sweet taste of fruit is a major factor for both consumption in natura and processing, we observed that jabuticaba fruits harvested 34 days after anthesis presented the best results.