Efeito do processamento por plasma atmosférico sobre as características de qualidade em suco de uva "Isabel"

Abstract

Recent studies have proved the positive effect of atmospheric plasma in a range of inactivating microorganisms and spores; however, less attention has been given to the emerging technology of this impact on the physico-chemical, nutritional and functional food. In this context, the present study investigated the effects of processing by atmospheric plasma on the quality characteristics in grape juice. Therefore, grape juice, obtained by centrifugation of the cultivar "Isabel" was exposed for 0 (control), 1, 2, 4, 6 minutes to a cold atmospheric plasma jet. Plasma was generated in helium gas by applying a dielectric barrier discharge (DBD) to a voltage 90kV, frequency of 10KHz and a gas flow of 2l/min. The physico-chemical characteristics (pH, soluble solids, titratable acidity, color, reducing sugars, phenolics and anthocyanins, antioxidant potential) and microbiological (Escherichia coli, coliforms, mesophilic aerobic, yeasts and molds) were compared before and after processing. The results indicate that under the experimental conditions used, the processing by atmospheric plasma remained the same physico-chemical characteristics of fresh grapefruit juice. Furthermore, after six minutes of treatment, a significant difference was found in bioactive compounds, at a magnification at a concentration of phenolics and antioxidant activity anthocyanins. Regarding the microbiological quality, no colony forming unit for mesophilic aerobic, molds and yeasts was observed after two minutes of treatment. However, despite the encouraging results, further investigation needs to be conducted in order to detail the food processed behavior during their lifetime.