| In this paper, three-years-experiments were conducted to examine the effects of heat treatments on prolonging preservation of strawberry (Fragaria ananassa Duch cv. 'Toyonoka'). Firstly, the effect of hot water pre-treatment with different temperatures on the postharvest qualities and physiology of strawberry fruits stored at 4℃and room temperature (20±2)℃respectively was evaluated. Secondly, the optimal pre-treatment with of hot water was applied to elucidate the relative expression of several genes involved in ethylene biosynthesis and ethylene receptor of fruits by using Semi-quantitative RT-PCR. Lastly, the effect of heat-steam pretreatment with 20-40s to preserve strawberry fruits under 4℃was investigated. And the mechanism of heat pretreatment prolonging the storage life of strawberry fruits was discussed in the paper. The main results were showed as follows.1. It was found in this work that hot water pre-treatment could prolong the storage life of post-harvested strawberry fruits. Anthocyanin accumulation, weight loss, decay index of the fruits were inhibited by hot water treatment. However, it stored at 4℃or room temperature (20±2)℃, and it was more advantage of preservation under 4℃. But, it is different that suitable temperature of treatment where the strawberry fruits ststored at 4℃or room temperature. Such as 45℃hot water treatment is best storing at 4℃, and 40℃hot water treatment is better if the fruits stored at room temperature.2. The results indicated that hot water pre-treatment significantly decreased anthocyanin accumulation, weight loss, decay index and respiration of the postharvested fruits, and maintained higher fruit firmness, activities of superoxide dismutase(SOD) and Ascorbate peroxidase(APX), but decreased the activities of lipoxidase(LOX), cellulase, the O2- production rate and MDA content. Therefore, heat-vapor treatment was helpful for strawberry to prolong the storage life.However, the effects of hot water pre-treatment on preservation of strawberry fruits was strengthen by increasing the treatment time to some extent.3. The respiration rate and the ethylene production of the strawberry fruits were inhibited by hot water wherever they stored. But there was no change in the trend with hot water pre-treatment. Semi-quantitative RT-PCR anlysis showed that hot water pre-treatment inhibited genes expression of ACS,ACO and ethylene receptor gene ETR1, ERS1. However, expression of ethylene receptor gene EIN1 was not influenced and maintained at a high level during the whole period of storage.4. Effects of heat-vapor pre-treatment on the preservation were investigated by using strawberry fruits. The results indicated that heat-vapor pre-treatment significantly inhibited anthocyanin accumulation, weight loss, decay index and respiration of the postharvested fruits, and maintained higher activities of superoxide dismutase(SOD), but decreased the activities of lipoxidase(LOX), cellulase, the O2- production rate and MDA content. Therefore, heat-vapor treatment was helpful for strawberry to prolong the storage life.5. The suitable heat treatment can reduce the senesecence of postharvest strawberry fruits, and is benefitable for prolong the storage life. Epidermises of strawberry fruits were injuried, if we did not well. For examble, the epidermis of strawberry fruits stored at 4℃and room temperature (20±2)℃were hurt with 50℃and 45℃hot water respectively, and 20～40s-heat-steam pre-treament also hurt the epidermis of strawberry fruits stored at 4℃.And it degraded external qualities and shortened preservation of the strawberry fruits. |
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