Study on Microbiology Controlling and Anti-oxidation Activity of Germinated Brown Rice
|School||Hunan Agricultural University|
|Keywords||Germinated brown rice Bacillus cereus ultraviolet radiation γ-aminobutyric acid antioxidative activity|
The dominant bacterial of germinated brown rice was isolated and identified, and the effect of the dominant bacterial on the germination of brown rice was investigated, and then, the effect of ultraviolet radiation (UV) on the bacterial count in germinated brown rice was investigated. At the end, the antioxidative activity of germinated brown rice during germination and drying was determined. The main results are following:The nutrient agar was used to isolate and count the bacterial, and the dominant bacterial of germinated brown rice was identified through26S rDNA sequencing. During the germination of brown rice, the count of bacterial reached7.08×108CFU/g in the end, one bacterial strain was isolated and its26S rDNA sequence had99.5%similarity with Bacillus cereus. The dominant strain of germinated brown rice was Bacillus cereus.Then, the effect of Bacillus cereus.on the germination of brown rice is investigated. The Bacillus cereus. is added into the germinating brown rice, the germinating rate, content of γ-aminobutyric acid (GABA), and sensory quality are determined, comparing with the control samples, which is added antibiotics to reduce the growth and propagation of bacteria. The reducing sugar is determined to partly find the mechanism. The results show that:Bacillus cereus decrease the germinating rate and the GABA content significantly, mightily due to the decreasing of reducing sugar. Furthermore, the bacillus cereus causes the acid-stinking bad odor. Therefore, it has to reduce the bacteria count during brown rice germination.During germination of brown rice, there were a large number of microorganism growths, resulting in food safety risk. And the effect of ultraviolet radiation (UV) on the bacterial count in germinated brown rice was investigated. The germinating brown rice was treated with UV (30W,3min, at a distance of25cm) every6h, from24h to48h, resulting in a distinct decrease of bacterial count (<105CFU/g), and the germinating rate did not decrease remarkable, the content of GABA slightly increased, and sensory quality improved. The germinated brown rice has numerous bio-activities, such as antioxidative activity, anti-tumor, anti-aging, etc. and the antioxidative activity is suggested as the basement. This paper investigates the antioxidative activity of germinated brown rice during germination and drying, through determining its capability of scavenging superoxide radicals. The results show that the germination improves the antioxidative activity drastic, especially germinated for6-18h. However, the drying decreases the antioxidative activity, and air-dried at65℃for1.5h or microwave-dried help to maintain the antioxidative activity of germinated brown rice.