김치 유래 유산균을 이용한 발효미강의 최적 조건 및 특성 분석

Abstract

Rice bran contains a variety of physiologically active substances, but most rice bran are used as animal feed and compost, and it is difficult to effectively utilize it. In this study, rice bran was fermented using L. plantarum EM and W. koreensis DB1, which are functional lactic acid bacteria separated from kimchi, and its characteristics were investigated. After preparing fermented rice bran according to the optimal fermentation conditions for each strain set in the previous study, the optimal drying conditions were set to 12 to 16 hours at 55°C during hot air drying and 3 to 4 days at -70°C during freeze drying. The number of viable cell of the rice bran fermentation product prepared under the optimization condition was detected to be about 102 CFU/g or less. As for the sensual characteristics, the preference of rice bran after fermentation was higher than before fermentation, and the freeze-dried product showed higher preference than hot-air drying. As a result of the functional evaluation, arginine was completely converted to ornithine in rice bran fermented with W. koreensis DB1, high cholesterol removal ability was confirmed in rice bran fermented with L. plantarum EM, and antibacterial activity of about 200 to 400 AU/mL was shown. In addition, both rice bran fermented with L. plantarum EM and W. koreensis DB1 exhibited high antioxidant activity. In the free sugar analysis, glucose and fructose were detected before fermentation, but after fermentation, both were exhausted by sugar metabolism, and in the organic acid analysis, the content of lactic acid increased after fermentation. A total of 11 components of fatty acids were detected, and in the results of free amino acid, arginine was high before fermentation in rice bran fermented with W. koreensis DB1, but the contents of ornithine and citrulline increased after fermentation. The characteristics of the fermented rice bran prepared under optimal conditions according to the storage period at 4°C and room temperature were investigated. As a result, all viable cell were dead after 1 month of storage, no other bacteria were detected, and ornithine content and cholesterol removal ability were maintained high. In addition, in the sensory evaluation, rancid flavour was felt from 6 months in the hot air-dried sample of the rice bran fermented with W. koreensis DB1, but rancid flavour was not felt in the rest of the samples. It was confirmed that the fermented rice bran developed from the experiment has excellent functionality and preservation, and it is a promising functional food.