Lasiodiplodia theobromae causes decay of star apple fruits (Chrysophyllum cainino) during harvest, transport and storage. If the irradiation dose is higher than 800 Gy, this mold will be controlled. However, the quality of star apple was significantly changed when they were irradiated at the dose higher than 0.6 kGy by electron beam (EB). To keep irradiation dose under 0.6kGy, the synergic effect of the combined treatment of EB irradiation and sodium dichloroisocyanurate (NaDCC) was investigated. In this study, star apples were pretreated with NaDCC concentrations in range of 10 -70 ppm in order to decrease the growth of mold and extend the shelf-life of treated star apples. The results showed that pretreatment with 20 ppm NaDCC had also kept the color and reduced disease of stored star apple. Dipping star apples into 20 ppm NaDCC solution before irradiating at 400 Gy and 600 Gy could be chosen as the best way to inhibit the development of Lasiodiplodia theobromae and extend the shelf life of star apple in the trading condition (7 days, 9oC).

We performed an in-plant calibration of dosimetry system by electron beam (EB)irradiating the B3 film dosimeters at VINAGAMMA, and inter-compared with the alanine dosimetry, which were supplied and analyzed by Risø High Dose Reference Laboratory (HDRL) as the reference standard. The results revealed that the relative deviation between the values of absorbed doses obtained with our dosimeter and the transfer standards dosimeter measured by HDRL was within the acceptable limitation (about ± 3.0 % in the target range of 2.0-10.0 kGy). And post-irradiation stability of B3 film dosimeters was still maintained after 180 days storage. It is suggested that the B3 filmdosimetry could be used in routine radiation processing at VINAGAMMA with the investigated dose range for quality assurance of the irradiated products, specially are foods and foodstuffs processed under the 10 MeV EB accelerator at VINAGAMMA.

Garlic powder was irradiated by gamma-rays from a Co-60 source to reduce microbialcontamination for prolong the storage and preservation time. Results showed that the initial microbial number of about 106CFU/g contaminated in garlic powder was exceeded for the set standard of TCVN 7809 – 2007 and ISO 5560 – 1997. The total aerobic bacteria and yeast mold cells of irradiated garlic powder were reduced from 106 CFU/g to 104, 6103 and 6102 CFU/g at doses of 0, 4, 8 and 12 kGy, respectively. The level of microbial contamination was significantly reduced by irradiation at 4 kGybut it is only appropriate for domestic acceptance. At the irradiation doses of 8 and 12 kGy, the level of microbial contamination was further reduced after storage for two months and it is appropriate to export. In addition, the irradiated garlic powder was in good quality with no change of moisture, oil content and sensory properties. Thus, gamma Co-60 irradiation is a very effective method for reducing the number of microbial contaminated in garlic powder.

Utilization of phytosanitary irradiation as a potential treatment to disinfest agricultural commodities in trade has expanded rapidly in the recent years. In this study, red mites (Tetranychus sp) isolated from cut Chrysanthemums were treated by electron beam irradiation at doses of 100, 200, 300 and 400 Gy. After irradiation, they were kept at room temperature to determine the effects of electron beam irradiation on red mite at different developmental stages (eggs, nymphs and adults) and the reproduction of female adults. The results showed that the pattern of tolerance to irradiation in red mite was eggs < 2nd instars < adults, in which the adults were the most tolerance stage. The number of eggs laid by the irradiated female mites and the hatching rate significantly decreased when the irradiation dose increased. The hatching rate of eggs at 300 Gy was 4.25% and no larvae F1 survived during observation time. It could be concluded that 300 Gy is the effective quarantine dose for red mite infesting on cut chrysanthemums.

Fresh cut flowers including yellow and white chrysanthemum (chrysanthemum sp) and red carnation (Dianthus caryophyllus L) were electron beam irradiated as quarantine treatment. The results showed that the irradiated flowers could meet the phytosanitary requirements in the international trading. In this study, the cut flowers were pretreated with the commercial preservative and sugar solutions in order to increase their radio-tolerance and expand their vase-life. The pretreatment has also reduced the weight loss, browning rate of leaves, and brightness of the irradiated flowers. The results revealed that the commercial quality of the irradiated cut flowers pretreated with 2% glucose solution 2 hours, then 0.024% silver thiosulphate (STS) solution for further 2 hours was remained after storage at 4-6oC. Pre-treatment with 2% glucose and 0.024% STS before irradiation at 400 Gy and 600 Gy was chosen as the best way for improving the raditain tolerance of the cut flowers. The vase-lifes of the irradiated cut flowers are 6 days for yellow chrysanthemum; 8 days for white chrysanthemum and 8-10 days for red carnation similar to non-irradition ones.