Combination of sonication with anti-browning treatments as a strategy to increase the shelf life of fresh-cut potatoe (cv. Monalisa)

Abstract

Two antioxidant solutions, a patented mixture based on vitamin C and other compounds (Natureseal ®, MV) and green tea extract (GT), were proposed to prevent browning in sliced potatoes. Combination with ultrasound (US) at two frequencies (35 and 130 kHz) was also evaluated, but no significant enhancement of the effects was detected with US. In MV-treated samples, respiration rate and dry matter (19.7 %) were higher than they were in the control (CK) (17.3 %) or GT-treated samples (16.8 %). Neither membrane integrity nor malondialdehyde content were significantly affected by the addition of MV or GT, but in MV-samples the antioxidant activity was increased 6-fold at the beginning of the storage (39.1 mmol ascorbic acid equivalents/kg), but decreased after 9 days. A yellowish coloration on the surface of GT samples was observed (L*a*b* values being 68.3, -6.4, and 25.3, respectively), attributed to the coloration of the tea concentrate. In the conditions studied, GT was not able to delay browning in potato slices. Contrarily, MV solution preserved the original colour of the sliced potatoes (69.6, -6.7, 27.7 for L*a*b*, respectively) during the 9-day storage at 4 ºC.