外源茉莉酸甲酯对草莓采后冷藏期间品质和抗氧化能力的影响

Effects of MeJA Exogenous Methyl Jasmonate on Postharvest Decay and Antioxidant Capacity of Strawberries during Cold Period

研究不同浓度的外源茉莉酸甲酯（Me JA）对＂丰香＂草莓（Fragaria ananassa Duch cv.Fengxiang）采后品质及果内抗氧化能力的影响。将供试草莓用Me JA在25℃下熏蒸处理9 h并摊晾2 h,最终Me JA浓度为1,100μmol/L。处理后置于5±1℃下贮藏（相对湿度90%~95%）。贮藏期间每隔3 d取3盒（每盒30果）测定其各项指标。试验表明,1μmol/L Me JA维持草莓贮藏后期较高的可溶性固形物（TSS）、显著抑制整个贮藏期间还原糖积累。1μmol/L Me JA处理能显著提高PAL（Phenylalanine ammonia-lyase）、C4H（Cinnamate-4-hydroxylase）活性,并延缓4CL（4-coumaroyl：Co A-ligase）活性的下降,从而有效诱导总酚和花青素类物质含量的增加,提高果实DPPH自由基清除能力,维持果实较高的抗氧化能力;100μmol/L Me JA处理对果实C4H和4CL活性的诱导效果不显著。适宜低浓度Me JA能够促进总酚和花青素的合成、提高DPPH自由基清除能力,可能是通过提高酚类、花青素等抗氧化成分合成途径关键酶PAL,C4H和4CL的活性实现的。因此,适宜浓度的Me JA处理在草莓采后抗氧化水平调节中具有重要作用。

Effects of different concentrations of exogenous methyl jasmonate（Me JA） on postharvest quality and antioxidant activity in strawberries（Fragaria ananassa Duch cv. Fengxiang） are investigated. Strawberries are treated by Me JA（1 and100 μmol/L） at 25 ℃ for 9 h,then cooling for 2 h. After treatment,strawberries are stored under 5±1 ℃（90%~95%RH.）. During storage period,3 boxes（30 fruits per box） are determinated for these indicators each 3 days. Results show that 1 μmol/L Me JA maintain higher content of TSS during later storage,significantly inhibit accumulation of reducing sugar during the whole period. 1 μmol/L Me JA significantly enhance activity of PAL,C4 H and delay the decrease in 4CL activity,thereby effectively increased levels of total phenolics and anthocyanins,improve DPPH radical scavenging activity. Those can maintain a high antioxidant capacity of fruits. The influence of 100 μmol/L Me JA on C4 H and 4CL activity in fruits is not significant. These results imply that properly low concentrations of Me JA evidently promoted the synthesis of phenolics and anthocyanins,maintain antioxidant activity through the regulation of key enzymes（including PAL,C4 H and 4CL） involve in phenols, anthocyanins and other antioxidants, thus finally improving the edible and nutritional quality of postharvest strawberries.