This study was carried out to investigate the economic value of organic rice production using gelatin ․ chitin microorganisms in eco-friendly complex, Gongsan, Naju city. The soil condition of experiment paddy field was Jeonbuk series and silt loam with a slightly poor drainage. Except for the high effective silicate, the chemical characteristics of soils used were included in the optimum range of paddy soils in Korea. In growth, plant length, tiller number, ear number, and ear length were observed to be higher in conventional paddy fields than organic paddy fields. However, number of grain per panicle and grain filling ratio (%) were higher in organic paddy fields than conventional paddy fields. Incidences of diseases and insect pests were slightly higher in the organic paddy fields. Water weevil, sheath blight, rice leaf roller and rice blast were more occurred in organic paddy field. On the other hand, false smut was higher occurred in conventional paddy field. There was a significant negative correlation between rice sheath blight and rice leaf roller, and rice yield. In the milled rice quality, the quality of organically cultivated milled rices was lower by the increase of broken rice than that of conventionally cultivated milled rices. The quality and palatability of rice were higher in organic cultivation with decreasing of protein content. Net income of conventionally and organically cultivated rice was 360,000 won/10a and 610,000 won/10a, respectively. Premium net income of the organically cultivated rice was 68%.

The objective of this study was to evaluate the effects of low temperature-adapted Saccharomyces cerevisiae Y297 and fermentation temperatures on the quality of Yakju brewed. Physicochemical properties of Yakju brewed were compared pH, total acidity, ethanol, free amino acid, organic acid contents, and volatile flavor compounds in S. cerevisiae Y297 with control treatment. Cooked non-glutinous rice and saccharogenic amylase in koji were mixed with ethanol-producing yeasts and then fermented at 15℃, 20℃, and 25℃ for 20 days. Yakju brewed using the Y297 treatment showed the highest ethanol yield (17.9%) at 20℃. Expression of heat shock protein (HSP) 104 was evaluated by immunoblotting as an indication of adaptation to low temperatures (15℃); levels of the HSP104 protein were higher in the Y297 treatment than in the control. Organic acid analysis showed that the lactic acid content of Yakju brewed using the control was the highest at 25℃. Finally, free amino acid analysis showed that the Y297 treatment had a higher proportion of essential amino acids than the control. Overall, these results indicate that S. cerevisiae Y297 could be used as a suitable yeast for Yakju brewed under low temperature (15℃) condition.

The objectives of this study were to isolate and characterize low temperature adaptation yeast and to obtain suitable yeasts strains for manufacturing Yakju. In this study, we isolated 482 wild yeasts from fermented foods. Out of these, 5 yeast strains were selected based on increased growth at low temperature (15℃) and high β-glucosidase activity. To screen the aromatic level of isolates, media containing cerulenin and 5,5,5-trifluor-DL-leucine (TFL) were used. Y297 strain demonstrated tolerance against TFL and produced more than 13% alcohol. Y297 strain was identified a Saccharomyces cerevisiae based on the 26S rDNA gene sequences. Maximum cell growth was observed after 19 hr and 38 hr of incubation at 25℃ and 15℃, respectively. The exponential phase was followed by a lengthy stationary phase, at 15℃, when the cells remained high viable. Y297 strain demonstrated tolerance against alcohol (10%), glucose (60%) and salt(NaCl, 8%). β-glucosidase and esterase activity in Y297 were higher than those of controls at 15℃. Overall, these results indicated that using wild yeast strain, isolated from fermented food, affects the chemical characteristics of the brewed Yakju.

1. 토양조건은 배수가 양호한 양토인 안룡통 보통답으로 칼륨을 제외하고는 우리나라 논토양의 평균 함량보다 낮은 토양이었다. 유기질비료로 처리구는 질소 표준시비량인 9kg/10a과 비슷한 N-P-K=8.45-4.89-9.24kg/10a를 시용한 반면 관행구는 표준시비량보다 많은 N-P-K=14.5-6.3-10.8kg/10a를 시용하였다. 2. 벼 수확 후 시험구 토양내 미생물상 분포를 조사한 결과 박테리아와 방선균의 수는 처리구에서 약간 높게 나타났고, 곰팡이의 수는 관행구에서 약간 높게 나타났다. 토양내 가수분해효소 생성미생물을 조사한 결과 호평벼 처리구에서 키틴분해미생물과 인산분해미생물 분포가 다소 높게 나타났다. 3. 병해충 발생정도는 전체적으로 처리구에서는 미미하게 발생하였다. 그러나 관행구에서 특히 호평벼에서 도복과 이삭도열병이, 잎집무늬마름병은 두 품종 공히 심하게 발생하였다. 혹명나방은 온누리에서 발생율이 높았는데 이는 질소 과다 시용으로 판단되었다. 4. 호평벼와 온누리 공히 관행구가 처리구에 비해 간장과 수장은 약간 길고, 주당수수는 많았다. 그러나 잎집무늬마름병 및 이삭도열병, 혹명나방 도복 등으로 등숙비율이 현저히 떨어졌다. 관행구는 천립중이 낮았으며 수량이 호평벼는 38%, 온누리는 13% 떨어졌다. 5. 병해충인 이삭도열병, 잎집무늬마름병, 혹명나방과 수량과의 관계에서 유의성이 높은 부의 상관관계가 나타났다. 6. 백미의 품질도 관행구에서 쇄립율의 증가로 완전미 비율은 낮고, 단백질함량이 높아 전반적인 품질 및 윤기치가 낮아졌다.