Microbial proteases are more economical than plant- and animal-derived proteases due to their ease of production and high activity. This study aimed to optimize the production of proteases from fermentative food-derived microorganisms. Five strains with proteolytic activity among 50 Bacillus sp. were first screened. Two strains with high protease activity were identified: Bacillus amyloliquefaciens SRCM 102139 and Bacillus subtilis SRCM 104999. SRCM 102139 strain and SRCM 104999 strain had the highest protease activity in 0.8% glucose and 0.3% yeast extract, and in 0.8% starch and 0.1% soy peptone, respectively. The production of protease for two strains was optimized by the Central Composite Design (CCD) under response surface methodology. The optimal conditions for protease production in SRCM 102139 were 0.5% and 0.347%, pH 6.0, for carbon (glucose) and nitrogen (yeast extract springer 0202) sources, respectively, with a predicted value of 0.929 U/mL. Additionally, the optimal conditions for protease production in SRCM 104999 were 0.5% and 0.5%, pH 6.7, for carbon (starch) and nitrogen (soy peptone HSP-349) sources, respectively, with a predicted value of 0.431 U/mL. The actual protease activities of SRCM 102139 and SRCM 104999 under the established conditions were 0.926 U/mL and 0.428 U/mL, respectively, closely matching the predicted values.

본 연구에서는 복분자 콤부차의 최적 배합비를 찾고 이화학적 특성과 항산화 활성을 알아보았다. 반응표면분석법을 통해 복분자 콤부차의 최적 배합비는 홍차 농도 10% (w/v), 복분자 농도 8.09% (w/v)로 나타났고 이 배합비로 홍차 발효 주정에 복분자 당침액과 균을 첨가하여 14일간 초산 발효와 젖산 발효 과정을 통해서 산도 4%와 pH 2.77인 콤부차를 만들 수 있었다. 복분자 콤부차의 주요 유기산은 acetic acid, lactic acid, oxalic acid로 나타났으 며 그 중에서 acetic acid가 3,705.34 mg/100 mL로 가장 높았다. 발효 후 총 폴리페놀의 함량은 763.33 μg CE/mL 로 발효 전보다 증가하였으나 콤부차 발효 후 DPPH, ABTS 라디칼 소거활성을 측정한 결과 항산화활성은 각각 46.09%, 89.81%로 발효 전보다 감소하는 것을 확인할 수 있었다. 또한 반응표면분석법을 통해 얻은 최적 배합비의 종속변수 예측값과 최적 배합비 콤부차 실험값의 산도의 평균차는 0.065, 유기산의 평균차는 0.041, ABTS 라디칼 소거활성의 평균차는 0.061이므로 예측값과 실험값은 유사 하다.

콩을 사용하는 간장제조공정과 달리 쌀을 사용하여 쌀소스를 제조 후 품질특성 및 관능적 평가를 실시하였다. 35oC로 하여 120일 숙성시킨 쌀소스의 품질평가 및 관능적 특성 결과 수분함량은 55.08%로 나타났으며, 색도측정 결과 L값은 38.90, a값 -1.22, b값 5.74로 숙성기간이 증가 할수록 황색도가 높게 나타나 b값이 증가하였다. pH는 4.35로 나타나 숙성 기간이 증가할수록 pH가 감소하는 경향을 나타났으며 총 질소 함량 측정 결과 0.26%로 나타나 숙성기간이 길어질수록 쌀의 단백질을 분해시켜 총 질소 함량은 높게 나타났다. 관능평가 결과, 숙성기간 120일 처리구가 숙성기간 90일 처리구에 비해 색의 기호도는 낮게 평가되었으나, 맛과 향의 기호도에서 높게 평가되었다. 따라서 쌀소스를 제조하는 경우에 숙성온도를 35oC로 하여 120일 숙성시키는 것이 관능적 품질 측면에서 가장 적합할 것으로 보이며, 본 연구를 바탕으로 생산된 쌀소스는 조미 식품으로써 쌀의 이용가치를 부가할 것으로 사료된다.

The objective of this study was to increase the efficiency of starch extraction from potato sludge by different concentration of food-grade hemicellulase. The potato sludge, which is a by-product of potato processing industry, was treated with food-grade hemicellulase. Starch extraction efficiency displayed no significant difference in hemicellulase concentration. The purities of potato starch increased from 83.40 to 95.91, 97.44, 95.58, and 97.79%, with treated 0.5, 0.75, 1.0, and 1.5% hemicellulase, respectively. The physicochemical properties of the starches, such as granule structure, particle size, pasting, and thermal transition, were not affected by the concentration of hemicellulase. These results indicate that food-grade hemicellulase treatment is an efficient method for starch extraction from potato sludge.

Millimeter waves are electromagnetic waves with frequencies of 30–300 GHz (wavelength 1–10 mm), and millimeter wave stimulation affects microorganism growth. The present study stimulated Bacillus subtilis with 60 and 70 GHz millimeter waves during cheonggukjang fermentation and characterized the effects on cheonggukjang quality. Cheonggukjang treated with millimeter wave irradiation showed no significant difference in total bacterial count but generated only 5.52-5.92% viscous substance. Irradiation with 60 GHz millimeter waves yielded bright and intense color values relative to 70 GHz millimeter waves. Examination of the amylase activity and reducing sugar content of finished cheonggukjang revealed that irradiation at 70 GHz inhibited amylase activity in cheonggukjang. Furthermore, irradiation at 70 GHz increased protease activity, whereas irradiation at 60 GHz inhibited the activity. Moreover, the amino acid content changed with millimeter wave irradiation.

Millimeter waves are electromagnetic waves with frequencies of 30–300 GHz (wavelength 1–10 mm), and millimeter wave stimulation affects microorganism growth. The present study stimulated Bacillus subtilis with 60 and 70 GHz millimeter waves during cheonggukjang fermentation and characterized the effects on cheonggukjang quality. Cheonggukjang treated with millimeter wave irradiation showed no significant difference in total bacterial count but generated only 5.52-5.92% viscous substance. Irradiation with 60 GHz millimeter waves yielded bright and intense color values relative to 70 GHz millimeter waves. Examination of the amylase activity and reducing sugar content of finished cheonggukjang revealed that irradiation at 70 GHz inhibited amylase activity in cheonggukjang. Furthermore, irradiation at 70 GHz increased protease activity, whereas irradiation at 60 GHz inhibited the activity. Moreover, the amino acid content changed with millimeter wave irradiation.

The objective of this study was to increase starch extraction efficiency from domestic potato by five kinds of foodgrade cellulases (mixture of β-glucanases, pectinase, cellulase, hemicelullase, and β-glucosdiase). Cellulase-treated potato had a maximum of 40% higher starch extraction yield than non-enzyme treated potato. It turned out that the shape and structure of cellulose-treated and nonenzyme-treated potatoes were the same. The average particle size of cellulose-treated potato starch was smaller than non-enzyme treated potato. Interestingly, the small starch granular (<10 μm particle) was shown in extracted starch from cellulose-treated potato. Rapid viscosity analysis showed that starch from cellulase treated potato had lower pasting temperature than starch from nonenzyme-treated potato. The range of the gelatinization temperature (49-62oC) of starches from cellulose-treated potato was broader than that of starches from nonenzyme-treated potato. Therefore, the results of this study confirm that cellulase plays an important role in the extraction of starch from the potato and physicochemical characteristics of potato starch.

Gamma-aminobutyric acid (GABA) is a functional component with physiological activity that helps to protect the liver from blood pressure reduction and alcohol damage, and is known to be widely distributed in various vegetables and fruits. In this study, a fermented rice syrup with enhanced GABA content was developed. The improved syrup was prepared by adding monosodium glutamate (MSG) to saccharified rice and using a complex of three types of lactic acid bacteria (Lactobacillus brevis, Lactobacillus plantarum, Leuconostoc mesenteroides ) with excellent GABA production ability. The physicochemical changes of the fermented rice syrup were measured, and the final pH of the product was 4.7 with a total water-soluble solid content of 22.1 °Brix. Of the dissolved solids, glucose (39.6 mg/mL) and maltose (12.7 mg/mL) were the main components, and it was confirmed that all MSG was converted to GABA. From the experiment, it was established that the rice syrup obtained from secondary fermentation of saccharified rice is suitable as a beverage base. The fermented saccharified rice syrup was differentiated from conventional rice fermented products which typically use yeast and acetic acid bacteria in the production process. The enhanced fermented rice syrup produced in this study was made using lactic acid bacteria in the fermentation and saccharified rice.

In this study, thirty-eight lactic acid bacteria (LAB) strains were isolated from Kimchi (Korean traditional fermented food) and screened for probiotic characterization in a series of in vitro tests, including resistance to low pH, tolerance to bile salts, hydrophobicity, antibiotic resistance and antioxidant activity. Firstly, twenty-two strains displayed survival in acid and bile passage conditions. Secondly, the strains KCCP 11349 and KCCP 11356 were observed to have high cell surface hydrophobicity with 63.9 and 98.8 %, respectively. Functionality of these potential probiotic isolates was supported by their antioxidant activity. Altogether, the strain KCCP 11349 showed characteristics similar to or even better than reference strain Lactobacillus rhamnosus GG. Finally, 16S rRNA gene sequencing was conducted to identify potential probiotic strains and KCCP 11349 was identified as Lactobacillus plantarum subsp. plantarum.