Postharvest putrescine and ultrasound treatments to improve quality and postharvest life of table grapes (Vitis vinifera L.) cv. Michele Palieri

Abstract

The main objective of this study was to assess the effectiveness of putrescine (Put) (1 and 2 mM for 10 min) and ultrasound treatments (32 kHz for 10 min) alone or in combination on changing biochemical compounds and extending postharvest life of grape. After treatments, clusters were packed in boxes with modified atmosphere packaging and stored at 1-2 degrees C with 90-95% relative humidity for 60 days. The weight loss, total soluble solids, titratable acidity, total anthocyanins, total phenolic content, antioxidant capacity, stem browning, decay rate and visual appearance at 0, 20, 40 and 60 days after harvest were recorded. Statistically significant differences were observed between different treatments in all measured parameters except for weight loss and total soluble solids. The data showed that individual Put or ultrasound treatment had a positive response in maintaining grape quality during storage, but conjugation of Put with ultrasound treatments showed better effects. Combination treatments maintained higher levels of anthocyanins, total phenolic content, antioxidant capacity and reduced the loss of sensory acceptability and decay incidence compared to control. At the end of the storage, control grapes markedly lost their quality, reaching below the critical marketable level while all the treatments preserved better the visual quality. These results demonstrated that the combined treatments of Put and ultrasound could be a promising approach to maintain postharvest storage quality of grapes.