| Summary: | 碩士 === 國立嘉義大學 === 食品科學系碩士班 === 90 === The samples of brown rice of the first crop season of seven japonica and three indica varieties, which supplied by Taichung District Agricultural Experiment Station, were examined for its g-aminobutyric acid (GABA)-enriching capacity during germination. The germination process carried out under 25℃, RH95% and dark condition in a growth chamber. Brown rice weighted about 5g of each variety were soaked in 30ml of ultrasound-treated tap water in a beaker and then germinated for 0, 12, 18, 24 and 36 hours to observe its sprouting and to determine its GABA and phytic acid content. The germination percentage of brown rice of japonica varieties generally showed a higher value than that of brown rice of indica varieties. While germinated for 36 hours, the length of sprout of brown rice of all the ten varieties were too long, i.e. 1mm or longer, to handle in hot air drying. Brown rice of Taikeng-X and Taichungsen-Y, germinated for 24 hours, had the highest GABA content among the ten varieties during the germination periods. The GABA content of germinated brown rice of the two varieties was 17.641 and 16.943mg/100g brown rice d.b. exhibited two to about three times rise compared to the original GABA content of 7.745 and 6.496 mg/100g brown rice d.b., respectively. While the content of phytic acid of brown rice of all the ten varieties showed no reduction during germination process. The Taikeng-X brown rice was selected for GABA-enriching experiment due to its high potential in GABA-enriching capacity and good eating quality.
Considering the GABA-enriching experiments was time-consuming and would cause the loss of sprouting ability of the brown rice of the first crop season, so the brown rice of the second crop season of Taikeng-X variety was, after the same characteristics in GABA-enriching was confirmed between brown rice of the first and second crop, selected for GABA-enriching investigation. Taikeng-X brown rice of the second crop season was undergone treatments of three stages sequentially for GABA-enriching. Different light qualities , at the first stage, crossed with three germination times, 12, 18 and 24 hours, for brown rice to enrich its GABA content. The data showed a rise of GABA content from original 11.21 to the peak value of 19.12mg/100g brown rice d.b., i.e. a 70.49﹪ rise in GABA content of brown rice gained under red light-24hr treatment at the first GABA-enriching stage. At the second stage, based on the red light-24hr treatment condition, three factors, pH of soaking water, concentration of glutamic acid and germination time, were used in central composite design which was taken to investigate the effect on GABA-enriching of brown rice, but, all the treatments, at this stage, only resulted in no significant effect on the accumulation in GABA content of germinated brown rice. At the last stage, ultrasound was taken to treat the brown rice treated previously by red light-24hr at the first stage. The result showed that there was no significant effect on the accumulation in GABA content for the sake of the dissolution of GABA into water due to ultrasound treatment. The brown rice, got form red light-24hr,then, dried in vacuum or by hot air combined with far infrared, and a preference panel test was carried out on the raw and two kinds of dried germinated brown rice, there was no significant difference found in preference among the three kinds of rice.
|
|---|
