羟丙基甲基纤维素涂膜处理对采后杨梅果实品质、生理及花色苷合成的影响

Effects of hydroxypropylmethylcellulose coating on qualities,physiological attributes and anthocyanin synthesis in postharvest Chinese bayberries

研究了羟丙基甲基纤维素(HPMC)涂膜处理对"乌种"杨梅果实冷藏期间品质、花色苷合成以及抗氧化活性的影响。将杨梅果实分别置于0.5%、1%、5%和10%的HPMC溶液中浸泡10 min,随后在室温下缓慢风干以在果实表面形成稳定涂膜,最后将果实于1℃下贮藏8 d,每隔2 d取样测定果实品质和生理指标、花色苷含量以及花色苷合成关键基因表达丰度。结果显示:采用5%的HPMC涂膜处理较其他处理浓度可更为有效的降低果实贮藏期间腐烂率,提高TSS和TA含量以及感官分数并抑制p H值的上升;5%HPMC涂膜处理可显著降低果实贮藏期间呼吸速率和乙烯释放量,延缓MDA含量和相对电导率的上升。另一方面,经5%HPMC涂膜处理的杨梅果实在整个贮藏期间PAL1和CHS基因的表达量均显著高于对照水平,并伴随着果实花色苷的积累以及DPPH自由基清除能力和总还原力的提升。由此推测,5%HPMC涂膜处理可显著延缓杨梅果实贮藏期间的衰老进程并降低呼吸底物的消耗从而维持果实品质和风味,并可有效诱导杨梅果实贮藏期间PAL1和CHS基因的表达以促进花色苷类物质的合成,最终提高了果实抗氧化能力。

The effects of hydroxypropylmethylcellulose （HPMC） coating on qualities, physiological attributes and anthocyanin synthesis in postharvest Chinese bayberries （Mycirarubra Sieb. et Zucc. CvWumei） during refrigera- ted storage were investigated in the present study. The selected Chinese bayberries were immersed in HPMC solutions at different concentrations （0.5,1,5 or 10 % ） for 10 min respectively, and then allowed to gently air-dry at room temperature in order to structure stable coating on the surface of the bayberries. Afterwards, the coated Chinese bay- berries were stored at 1 ℃ for 8 d. The quality and physiological parameters, anthocyanin contents and expression levels of anthocyanin synthesis-related genes were measured at 2-day intervals. The results showed that 5 % HPMC coating treatment was the most effective in reducing the decay incidence, enhancing the contents of TSS and TA and sensory scores as well as inhibiting the increase in pH value among all coating treatments. 5 % HPMC coating also re- markably lowered respiration rate and ethylene production, and delayed the increase in MDA content and electrical conductivity in the fruits during the storage. The fruits coated with 5 % HPMC exhibited the significant higher gene expressions of PAL1 and CHS than control during the whole storage, and the accumulation of anthocynin and promo- tion of scavenging capacity against 1,1-diphenyl-2-picrylhydrazyl （DPPH） and reducing power were increasing. Therefore, it is speculated that 5 % HPMC coating could significantly delay the senescence process and reduce the consumption of the respiratory substrate, resulting in maintaining the fruit quality and flavor. Meanwhile, the en- hanced antioxidant activity in 5 % HPMC-coating treated bayberries could be mainly attributed to its increase in the accumulation of anthocyanin compounds, which were effectively promoted due by the high level expressions of PAL1 and CHS genes.