UV-C and ozone treatment influences on the antioxidant capacity and antioxidant system of minimally processed rocket (Eruca sativa Mill.)

Abstract

In this work, treatments with UV-C light (20 kJ m−2) and gaseous ozone (2 mg L−1 O3) were applied to minimally processed rocket (Eruca vesicaria subsp. Sativa) leaves to investigate their effects on the antioxidant capacity and antioxidant system throughout 8 ds at 5 °C. As control, water washing was used. On 8 d, the ascorbic acid content was reduced about 50% both control and treated samples. Treatments with 20 kJ UV-C m−2 or 2 mg L−1 O3, did not affect the phenolic content neither the total antioxidant capacity, remaining almost constants during storage. The phenylalanine ammonia lyase (PAL) activity had no significant variations during storage, in correlation with the content of phenolics. As to the enzymes involved in the antioxidant system, an increase in its superoxide dismutase (SOD) activity with respect to uncut rocket leaves was detected after the process. In turn, enzymes that remove H2O2 like ascorbate peroxidase (APX) and catalase (CAT) showed no significant changes. During storage at 5 °C, the SOD activity remained unchanged while APX and CAT showed a gradual increase in both treated and untreated samples. In conclusion, the UV-C and ozone treatments applied inhibited the growth of spoilage by bacteria as well as by yeasts, extended shelf-life, without exerting significant additional stress with respect to the cutting stage of the leaves, reason by which they did not trigger a greater activation of the antioxidant system.