Abstract:
UV-C irradiation can conplctcly inhibits the sporc gemination of .Aspergillus Flavus at an exposure dose of 3.9 1 kJ/m- exposure dose additionally delaying mcelium growth on media. The growth of inycelium was inhibited by gamma irradiation (Co-60) at an cxposurc dose of 4.45 kGy, but the spore germination was significantly reduced to 97% at a dose of 5.62 kGy. Galnma in-adiation (6 kGy) was applicd to brown rice (cv. Khao Dok Mali 105), which uns pnckcd in two different ways: vacuum-scaled in SS micron polyethylene bags vcrsus non-vacuum-seal bcing stored at different teinperaturcs (15 'C and ambient) for 4 months. Gamma in-adiation climinatcd SO% of fungal growth on inoculated brown rice by the end of storage time. Although gamina in-adiation reduced atlatoxin B, to 41.33% in YES media. this cffcct on brown rice was not evident. Iiradiation reduced the quality of inoculated broivn rice compared to non-irradiated samples of. either. inoculated and non-inoculated brow rice (conti.ol). The total lipid and pH of brown rice were reduced while the b* value (yellowing). free fatty acid, TBA and the lipase activity was increased. Howcvcr, total protein. amylase content and lipoxygenase activity remaincd unchanged. During storagc. cspccially at room temperature, the quality of inoculated and irradiated brown rice decrcnsed most quickly followcd by inoculated brown rice without in-adiation. finally the control sample. Our investigations also revealed an increase of PBA, fi-ee fatty acid and lipase activity. The result was similar but less apparent coinparcd to brown rice kept at 15 ?C. In general. vithin all sainples, the moisture content decrcascd from 11.8% to 8-9% (equilibrium) within the third inonth of storagc. Irradiation and inoculation were slightly effective on amylose content, but storagc at rooin tcmpcrature caused a little increase of the amyIose content faster than that at 15 ?C. In contradiction to the quality degradation due to gamma irradiation, these packaging methods did not affect the quality of the brown rice significantly.