Abstract:

Raspberry fruits were sprayed with 1 mmol/L salicylic acid 1, 2 or 3 times every 3 days before harvest, harvested and stored at 1 ℃. Their sound fruit rate, contents of bioactive components, and antioxidant capacity were determined after storage for 10 or 23 days. The results showed that 2-time and 3-time pre-harvest salicylic acid spray treatments both increased significantly sound fruit rate and 2-time salicylic acid spray treated raspberry fruits revealed higher sound fruit rate than 3-time salicylic acid spray treated ones. Each pre-harvest salicylic acid spray treatment improved the contents of anthocyanins, total phenolics, total flavonoids and total antioxidant capacity, hydroxyl and DPPH radicals scavenging capacity, whereas obviously decreased the content of H2O2 of freshly harvested raspberry fruits. The most obvious changes in these parameters were observed in 2-time pre-harvest salicylic acid spray treated raspberry fruits. In addition, pre-harvest salicylic acid spray treated raspberry fruits exhibited an increase in the contents of H2O2 and total flavonoids and DPPH radical scavenging capacity and a decrease in the contents of anthocyanins, total phenolics and total antioxidant capacity and hydroxyl radical scavenging ability during postharvest storage. Pre-harvest salicylic acid spray treatment induced the generation of secondary metabolites and the enhancement. of DPPH radical scavenging capacity of raspberry fruits so that their post-harvest storage quality was improved.

Key words: raspberry fruit, pre-harvest spraying, salicylic acid, antioxidant capacity