Effect of Gamma Irradiation on Quality and Composition of Sakkoty Date Fruits (Phoenix dactylifera L.) During Storage

Abstract

This study was carried out to improve the quality and the shelf-life of Sakkoty date variety during storage period at room temperature using gamma irradiation doses of 0, 1, 2 and 4Kilo Gray (KGy). The effect of radiation treatments on the quality and composition of samples were evaluated at 0, 4, 8 and 12 months of storage. Results showed that the irradiated fruits with 4KGy are more effective for controlling the insect infestation (3.22%) followed by the irradiated date sample with 2KGy (6.00%) and 1KGy (6.45%). While, the control sample recorded 24.25% at the end of storage period. The moisture content of the control date sample decreased from 11.64 to 8.33% at the end of storage while it was decreased from 11.94 to 8.04%, from 11.89 to 8.35% and from 11.61 to 8.28% for the irradiated fruits by 1, 2 and 4KGy, respectively. However, the content of all sugars immediately decreased after irradiation, while it were increased gradually with increasing the storage time. Data revealed that the total bacterial counts immediately decreased after irradiation to a great extent, compared with the reduction in molds and yeasts. Beside, the microbial flora in all used doses were remained at a low count until the end of storage period. The irradiated sample with 4KGy had the lowest microbial counts, followed by the irradiated samples by 2 and 1KGy, respectively. The organoleptic evaluation showed that the panelists can not discriminate between the non-irradiated and irradiated date fruits. Furthermore, all the studied doses have no detectable adverse effect on the preference rating of the fruits. The irradiated sample with 1KGy was occupied the first rank in overall acceptability of sensory evaluation followed by the irradiated samples with 2KGy and with 4KGy. These results suggest that the packing irradiated fruits by 1, 2 and 4KGy of Sakkoty date fruit can be used as alternative method for improving the fruit quality, as well as prolonging its marketable period at room temperature for 12 months.