Quality assessment of ‘Fuyu’ persimmon treated by a combination of γ-irradiation and 1-methylcyclopropene

Abstract

quarantine requirements of the various countries must be satisfied. To achieve this, fumigation (e.g., methyl bromide), extreme temperatures, the use of controlled atmospheres, irradiation, and combinations of the above are commonly employed (2). More specifically, methyl bromide (CH 3 Br) treatment is often used for pest control because it has a wide spectrum of activity (3). However, an eco-friendly replacement for methyl bromide was necessary due to its phase-out requirements outlined in the 1987 Montreal Protocol on Ozone Depleting Substances (4). In addition, irradiation is an effective and eco-friendly non-chemical treatment for the eradication of harmful insects in fruits and vegetables (5,6). It has been also suggested that ionizing irradiation could be employed to sterilize or kill pests without damaging the flowers (7), with γ-irradiation doses <1 kGy being permitted for treating the majority of fresh fruits and vegetables (8). However, high doses of radiation can promote the softening of persimmon fruits, which renders them undesirable and unmarketable. Quality assessment of 'Fuyu' persimmon treated by a combination of γ-irradiation and 1-methylcyclopropene

Effect of Phytosanitary Irradiation Treatment on the Storage Life of ‘Jiro’ Persimmons at 15 °C

“…The effects of irradiation treatment on fruit respiration rates are presented in Figure 4 and show that the treated persimmon fruit had higher respiration rates than untreated fruit. Similar results have been observed where irradiated 'Fuyu' persimmon fruit had higher respiration rates during storage [9,10]. Higher fruit respiration rates during storage can indicate fruit stress or more mature fruit [19] and can be exacerbated with the use of MA bags, which are common for the long-term storage of persimmon fruit.…”

“…This is also illustrated in Figures 2 and 3, which show the photos of the fruit three days after treatment ( Figure 2) and after three weeks storage at 15 • C (Figure 3), where these observed differences between the treatments were not outside commercial acceptability. Previous research on the effects of low dose irradiation on persimmon fruit quality have shown no effect of irradiation treatment on 'Fuyu' fruit colour [9,10]. There was no effect of irradiation treatment on fruit weight loss during storage at 15 • C (Table 1).…”

“…This was supported with the observations of the subjective fruit firmness, where no differences in the subjective physical feel of the fruit were detected between the treatments. However, other studies have shown irradiation treatment at 400 and 800 Gy resulted in softer 'Fuyu' fruit after 60 days of storage at 0 • C [10]. These observed differences in fruit firmness responses to irradiation treatment may be due to the differences in storage temperature and time.…”

“…There have been very few studies on the effects of irradiation as a quarantine treatment on persimmon fruit with low dose phytosanitary treatment doses [9,10], with other studies conducted on higher irradiation doses above the phytosanitary limit (1000 Gy maximum). For example, 'Hachiya' persimmons were treated with a range of irradiation doses (1500-3500 Gy) [11], but these treatment doses are not representative of any commercial market access treatment [6].…”

“…While 15 • C is not the ideal storage temperature for persimmons, this temperature was chosen as a representative of an export supply chain. The single commercial irradiation treatment dose was selected as a previous study showed no differences in irradiation dose (200, 400, 600, and 800 Gy) on 'Fuyu' fruit quality following treatment and storage [10]. 'Jiro' along with 'Fuyu' belong to the pollination constant non-astringent group of persimmons, which are non-astringent fruit.…”