Pre-harvest application of polyamines enhances antioxidants and table grape (Vitis vinifera L.) quality during postharvest period.

Pre-harvest foliar spraying of grapevines with putrescine (Put) and spermidine (Spd) (0, 1, 2mM) was evaluated for determining the fruit quality at harvest and improving postharvest characteristics of table grapes during cold storage. Fruit parameters in terms of firmness, fungal infection, weight loss, total phenol concentration, antioxidant activity, skin color, total anthocyanin concentration, total soluble solids (TSS) and titratable acidity (TA) were evaluated after 0, 25 and 55 days of storage at 1.5 ± 1 °C and 90 ± 5% R.H. Softening, fungal infection and weight loss increased during cold storage but the rate of changes significantly was delayed in Put- and Spd-treated fruits. Besides these, the application of Put and Spd maintained higher values of phenolics content, antioxidant activity and anthocyanins at the end of storage in compare to control. Furthermore, after 55 days of storage all treated fruits with Put and Spd showed lower changes in L(∗), TSS and TA and also higher value of chroma in berries.