Accumulation Of γ-Aminobutyric Acid In Immature Brown Rice And Development Of Rice Beverage

Immature brown rice is the grain of rice which has not yet ripe and full, appearance looks powder, but still has nutritional value. Because of immature brown rice has high quality content of starch granules arranged in unconsolidated, and has low relative density, its easy to be breaken and fracture during the milling process. Increased rate of broken rice, reduced real milling yield and head rice rate. Effects on brown rice processing quality, production procedure often removed immature brown rice to improve processing quality. However, immature brown rice still has some food value and is rich in starch, removing it is not only a serious environmental pollution, but also caused a large amount of food waste and economic loss. The changes of physic-biochemical compounds and y-aminobutyric acid (GABA) content during germination of immature brown rice under hypoxia stress were investigated, optimal concentration of GABA germinated culture conditions, preliminary studies on physicochemical properties of immature brown rice, and the GABA-enriched immature brown rice beverage was developed on this bases. The main results were summarized as follows:1. During 48 h of hypoxia stress germination period, main physiological activity and chemical composition of immature brown rice has series of changes. By hypoxia stress germination 48 hours, the sprout length was 1.92 mm, respiration rate increased by 5.6 times, density was 0.79 mL/g, starch content decrease 13.3%, reducing sugar content was 2.7 times of 0 h, content of free amino acids increased 3.19 times, the content of GABA was 2.08 times of 0 h which reached 227.7 μg/g, the content of Glu was only 141.8 μg/g, 54.6% of the beginning, GAD activity was 18.5 U/g. The results indicated that the sprout length, germination rate, free amino acid content, GAD activity and GABA were significant positive correlated, correlation coefficients were higher than 0.96, Glu and GABA were significant negative correlated.2. During the period of hypoxia stress germination, the sprout length, germination rate, starch content, reducing sugar content, free amino acid content, GABA content, Glu content and GAD activity of immature grain and ripened grain of brown rice has no significant differences, which indicates that immature brown rice by hypoxia stress germination can improve its nutritional quality and be used as good test materials for GABA enrichment.3. The germinated immature brown rice was made into a kind of GABA-enriched immature brown rice beverage, using single element and orthogonal experiment to optimize the rice beverage production. Results showed that the basic ingredients of GABA-enriched beverage were as follows:rice baked 10 min at 200 ℃, the optimum ratio of sample and solution was 1:8 add 0.3% alpha-amylase and reacting for 30 min, the beverage was emulsionized with 0.03% of monoglycerides and 0.07% of sucrose ester, ratio was 3:7, HLB value was 11.8. Recipe was whole milk powder 2%, white granulated sugar 4% and salt 0.1%. The stabilizer prescription of GABA-enriched beverage was: 0.08% of compound emulsifier,0.02% of gellan gum and 0.04% of xanthan, the beverage has the best stability. Results also showed that the beverage was "most acceptable" level, and was in accordance with consumer drinking requirements.