Comparison of traditional hot water and vacuum assisted blanching methods on the physico-chemical quality parameters and antioxidant activity of zucchini (Cucurbita pepo L.) slices

This study aimed to compare the effects of hot water and vacuum blanching methods on physico-chemical parameter, total phenols (TPC) and flavonoids content (TFC), and antioxidant activity of zucchini slices during 28 days storage. A significant decrease in Chroma parameter was observed over time, on the other hand, no significant differences were observed between the Hue angle ​​either between samples treated with the two blanching methods or during storage. A minimal reduction in the TPC was observed in all samples, independently by the applied treatment, compared to the value of untreated product whereas a more marked reduction in TFC compared to untreated zucchini slices was observed (− 39.91% and − 32.02% for vacuum blanched (ZS8) and hot water blanched (ZB8) zucchini treated for 8 min, respectively, respect the untreated zucchini samples at D0). First-order kinetic model was applied to monitor the effect of the two blanching processes on zucchini slices. The application of vacuum blanching allows for greater retention of bioactive compounds over time with a half-life time (t1/2) of 161 and 47 days for ZS8 versus 87 and 23 days for ZB8, respectively. Samples treated with both blanching procedure for 8 min exhibited a more markedly ABTS radical activity respect untreated one (IC50 values of 17.55 and 14.98 μg/mL for ZS8 and ZB8, respectively vs 20.45 μg/mL for untreated zucchini). In general, the results obtained allow to identify in the vacuum treatment a method applicable to zucchini slices to maintain their qualitative characteristics over time.