Durante muito tempo os esforços da pesquisa em tecnologia de alimentos foram centrados na conservação de matérias-primas in natura, com o objetivo de prolongar sua vida útil. As condicionantes atuais da produção de refeições colocam uma nova necessidade, a de produtos prontos para o consumo. Existe uma tendência mundial para usar alimentos cada vez mais naturais, valorizando o sabor original dos produtos, na qual o consumidor, disposto a pagar mais pela qualidade, apresenta um nível de exigência cada vez maior. É neste cenário que surgem os alimentos processados minimamente, que unem a praticidade e a conveniência, proporcionando uma economia de tempo no preparo dos alimentos.O processamento mínimo é definido como qualquer alteração física causada em frutas e hortaliças e que mantém o estado fresco destes produtos (INTERNATIONAL FRESH-CUT PRODUCE ASSOCIATION, 1999). Inclui as operações de seleção, limpeza, lavagem, descascamento, corte, sanificação, centrifugação e embalagem, ou seja, operações que não afetem suas características sensoriais e agreguem valor aos mesmos, resultando em produtos naturais e práticos, cujo preparo e consumo requer menos tempo, atendendo às exigências da vida moderna (DAMASCENO; STAMFORD; ALVES, 2001). AbstractStrawberries cv. Oso Grande were minimally processed and kept in three different atmospheres: 3% O 2 + 10% CO 2 (N 2 balance), 3% O 2 + 15% CO 2 (N 2 balance) and ambient atmosphere (control), at 5 and 10 °C, during 7 days, with the evaluation of their physical and chemical characteristics during storage. Fruits were evaluated at 0, 3 and 7 days for weight loss, firmness, pH, titratable acidity, soluble solids, sugar content (sucrose, fructose and glucose) and total anthocyanins. Data were subjected to analysis of variance (ANOVA) and means were compared by the Least Significance Difference (LSD) test (5%). It was verified that shifting the temperature from 5 to 10 °C had no significant effect on the physical and chemical variables analyzed. The utilization of atmospheres 3% O 2 + 10% CO 2 and 3% O 2 + 15% CO 2 was important for quality maintenance of fresh-cut strawberries. They better preserved firmness in relation to ambient atmosphere, and had a positive effect on the control of fruit weight loss. However, fresh-cut fruits kept under those atmospheres showed a lower content of anthocyanins when compared to fruits stored in ambient conditions. Keywords: Fragaria x Ananassa Duch; minimal processing; atmospheric control; refrigerated storage; quality. ResumoMorangos cv. Oso Grande foram processados minimamente e mantidos em três diferentes atmosferas: 3% O 2 + 10% CO 2 (balanço N 2 ), 3% O 2 + 15% CO 2 (balanço N 2 ) e atmosfera ambiente (controle), a 5 e 10 °C, durante 7 dias, com o objetivo de avaliar suas características físicas e químicas ao longo do armazenamento. Os frutos foram avaliados nos dias 0, 3 e 7 quanto à perda de massa, firmeza, pH, acidez titulável, sólidos solúveis, açúcares (sacarose, frutose e glicose) e teor de antocianinas totais. Os dados foram submetidos...

No abstract

Este trabalho teve como objetivo a obtenção de suco clarificado de maracujá, utilizando a técnica de microfiltração. Introduziu-se a etapa de tratamento enzimático antes da microfiltração, visando aumentar a eficiência do processo pela redução da viscosidade e do teor de polpa do suco. Foram testadas três diferentes enzimas hidrolíticas em três níveis de concentração. Os resultados não mostraram diferenças significativas quanto ao Brix, pH e acidez das amostras de suco hidrolisado em relação ao suco integral. Observou-se efeito positivo da ação das enzimas na redução da viscosidade e do teor de polpa. A microfiltração foi realizada em sistema de membrana tubular com tamanho médio de poro equivalente a 0,3 µm e pressão transmembrana de 1,5 bar. O suco permeado apresentou-se límpido, isento de polpa e com qualidade e sanidade microbiológica. Tais resultados comprovaram a eficiência da microfiltração para clarificação e estabilização de sucos de frutas. IMPROVEMENT IN THE EFFICIENCY OF PASSION FRUIT JUICE CLARIFICATION BY THE COMBINATION OF MICROFILTRATION AND ENZYMATIC PROCESSES Abstract This work had as objective the obtention of clarified passion fruit juice by using the microfiltration technique. A step of enzymatic treatment was introduced before microfiltration, aiming to enhance process efficiency by reduction of viscosity and pulp content of the juice. Three different hidrolytic enzymes were tested in three concentration levels. The results didn’t demonstrate significant differences in Brix, pH and acidity of the hidrolyzed juice samples in relation to the concentrated juice. Positive effect was observed in the action of the enzymes in the reduction of viscosity and pulp content. The microfiltration was realized in a tubular membrane system with average size of the pore equivalent to 0.3 m and transmembrane pressure of 1.5 bar. The permeate juice was clear, free from pulp and with good micribiological quality. Such results proved the efficiency of microfiltration for clarification and stabilization of fruit juices.

Concentrated extracts of graviola leaves, which are widely discarded during the pruning of trees in commercial crops, were obtained by different membrane concentration process. These leaves are commonly used in traditional medicine due to their pharmacological properties. In this study, hydroalcoholic extracts (with 50 or 70% of ethanol (v/v)) of graviola leaves were subjected to ultrafiltration (UF), nanofiltration (NF) and to combination of both processes (UF followed by NF). The concentrated fractions coming from these processes were analyzed for their total antioxidant capacity and total phenolic content in order to evaluate the selectivity of each concentration step. Processes performance were also evaluated for productivity (permeate fluxes) and energy consumption, which allowed the choice of the best membrane filtration system in terms of energy savings and of interest compounds retention. The combination of processes of UF and NF showed retention coefficients higher than 75% in concentration of phenolic compounds. This sequential design resulted also in higher fluxes of NF, the fluxes increased almost seven times for extracts with 50% of ethanol, and almost three times for extracts with 70% of ethanol when compared to direct processes o NF. Furthermore, the combined system of UF and NF promoted a significant reduction in the concentration time of the extracts by NF and the characterization of fouling mechanisms, which is important parameters to scale-up of this process, indicated that the strategy may increase the useful life of the membranes.

No abstract