采前涂膜对‘泰山红’石榴采后贮藏品质的影响

Effect of Preharvest Coating on the Quality of ‘Taishanhong' Pomegranate during Storage

以‘泰山红’石榴为材料,研究采前1.25%壳聚糖溶液涂膜(T1)和石榴皮提取液复合涂膜(T2)对石榴果实采后贮藏品质及生理指标的影响。结果表明:采前两种涂膜剂涂膜后,均能增大‘泰山红’石榴近外表皮的薄壁细胞,但作用不显著;‘泰山红’石榴在(4.0±0.5)℃条件下贮藏,能有效保持其表皮新鲜程度,维持其果皮内含水量;涂膜对提高贮藏前期石榴籽粒可溶性固形物含量和降低贮藏前期可滴定酸含量有一定影响,但对贮藏后期影响不显著;涂膜能使石榴果皮中总酚含量和类黄酮含量维持在较高水平,减少贮藏前期因膜脂质过氧化产生的丙二醛;此外,T2复合涂膜还能延迟多酚氧化酶活性高峰出现的时间,同时提高多酚氧化酶活性的峰值;而T1涂膜影响不显著。采前涂膜石榴贮藏120 d果实外观新鲜无皱缩,色泽鲜艳,腐烂率较对照低,保鲜效果较为理想。

In this study, either 1.25% chitosan(T1) or its combination with pomegranate rind extract(T2) was uniformly sprayed on ‘Taishanhong' pomegranate fruits, harvested and then stored at(4.0 ± 0.5) ℃ for 120 days. The weight loss, total soluble solid, titratable acidity(TA), malondialdehyde(MDA) content, total phenol content, polyphenol oxidase(PPO) activity, total soluble solid content, and decay incidence were investigated during storage. Results indicated that the number of parenchyma cells close to the outer epidermic layer increased yet not significantly after both preharvest coating treatments. Meanwhile, the freshness and moisture content of pomegranate peels were effectively maintained, and these coating treatments could result in an increase in TSS content and a decline in TA content during the early stage of storage, while not having a significant effect on the two parameters during the later stage of storage. Moreover, the contents of total phenols and total flavonoids in pomegranate peels were maintained at higher levels and MDA formation caused by membrane lipid oxidation was reduced during the early storage stage. In addition, T2 treatment could delay the occurrence of the peak of PPO activity and increase the peak enzyme activity, while T1 treatment was not as effective in this regard. In conclusion, preharvest coating could increase the shelf life and maintain the sensory quality of ‘Taishanhong' pomegranate fruits.