Effects of methyl jasmonate on physicochemical qualities and internal browning of ‘queen’ pineapple fruit during cold storage

The effects of methyl jasmonate (MeJA) as a protectant against chilling injury on physicochemical qualities of ‘Trad-see-thong’ pineapple (‘Queen’ group) fruit was investigated. The pineapple fruit were immersed in 1 mM MeJA for 5 min and then stored at 10 ± 1°C for 20 days. MeJA had no effect on respiratory rate and pulp colour, but suppressed ethylene production during cold storage. Weight loss, ion leakage (IL), internal browning (IB), and loss of pulp firmness were inhibited by MeJA. The MeJA treatment also suppressed the reduction of lightness (L*) and yellowness (b*) and the increase of total phenols (TP) that commonly occurs during cold storage, and increased the polyphenol oxidase (PPO) activity of pulp adjacent to the core (PAC) tissue. Certain bioactive compounds, such as ascorbic acid (AsA) and superoxide dismutase (SOD) in PAC tissues were enhanced by MeJA. No significant difference in peroxidase (POD) activity in both pulp and PAC tissues were detected between the treated and control fruits. These results suggest that immersion in MeJA is an effective means to maintain quality, alleviate IB symptoms, and enhance certain bioactive compounds in ‘Queen’ pineapple fruit cv. Trad-see-thong during cold storage.