Kye-Man Cho’s research while affiliated with Gyeongnam National University of Science and Technology and other places

To develop health-functional food ingredients for improvement of diabetes, we examined biological activities, including total contents of polyphenols and flavonoids, antioxidant activity, and inhibition of α-glucosidase and pancreatic lipase activities of ethanol extracts from unripe fruit of Momordica charantia L. cultivated in Hamyang, Korea. Ethanol extracts were tested using different ethanol concentrations (0%, 30%, 50%, and 70%) and temperatures (50°C and 70°C). Experimental results showed that total polyphenol and flavonoid contents were achieved concentrations of 7.77 mg/g (tannic acid), 7.66 mg/g (gallic acid), and 10.66 mg/g (rutin). The hydroxyl radical scavenging, ABTS cation radical scavenging, and FRAP activities were 82.19%, 42.82%, and 0.19 under the same conditions, respectively. The highest inhibitory activities of α-glucosidase and pancreatic lipase were achieved in the 70% ethanol extract at 70°C. These results will be useful for development of health functional foods for anti-diabetes using 70% ethanol extract from unripe fruit of bitter melon © 2015, Korean Society of Food Science and Nutrition. All rights reserved.

In this study, the β-glucosidase activity and total phenolic and isoflavone contents and antioxidant activities during Cheonggukjang fermentation with bitter melon powder (BMP) were investigated and evaluation of the same was performed. The level of β-glucosidase activity was increased at 48 hr and decreased after 72 hr, and the total phenolic and isoflavone-malonylglycoside and aglycone contents increased, while the antioxidant activities increased, but the total isoflavone and isoflavone-glycoside contents decreased during the Cheonggukjang fermentation. In particular, the soybean with 5% BMP fermented at 37°Cfor 72 hr displayed the highest antioxidant activities, among all the samples. The highest levels of total phenolic and daidzein contents and DPPH radical scavenging activity, ABTS radical scavenging activity and FRAP assay results after 72 hr fermentation in Cheonggukjang with 5% BMP were found to be 13.5 mg/g, 390.57 μg/g, 90.74%, 99.79%, and 1.705 (OD593 nm) respectively. In addition, the more BMP was added to the Cheoggukjang, the more the off-odor of the Cheonggukjang decreased. These results suggest that BMP can be used to come up with a new type of Cheonggukjang with improved palatability and antioxidant activity.

We investigated the changes in the quality characteristics of Doenjang with low salt contents (6, 8, 10, and 12%) and 10% garlic. The Doenjang was analyzed at an interval of a week during its fermentation for six weeks, at room temperature. Its L color gradually decreased, but its a and b colors did not change significantly. Its salinity increased by about 1% after six weeks. In contrast, immediately after its preparation, its pH was gradually decreased and its acidity was increased for the fermentation. The reducing sugar was significantly increased from 1.34~1.88 g/100 g immediately after its preparation to 7.25~9.13 g/100 g after six weeks, which was higher as the salt concentration decreased. The amino-type nitrogen doubled from 100~130 mg% at 0 week to 210~290 mg% at six weeks, which were lower with the higher salt concentrations. The growth curve of the Bacillus fermentation strains of Doenjang increased to two weeks but gradually decreased since, and the growth of the Bacillus was favorable for up to two weeks in the Doenjang with 10% and 12% salt added. Otherwise, the yeast was reduced rapidly during the early fermentation of the Doenjang, and slightly changed after three weeks of fermentation. The results of this study showed that the reducing sugar and amino-type nitrogen contents of the low-salt garlic Doenjang were higher with the lower salt dose, and the physicochemical quality of the 6%-salt Doenjang was not significantly affected. Thus, we suggest that low-salt Doenjang can be manufactured with the addition of 6% salt and 10% garlic.

In this study, we investigated the quality characteristics of Korean soybean paste, Doenjang, fermented for 6 weeks at room temperature with the addition of 0, 10, 20 and 30% garlic. Samples were analyzed in one-week intervals. The lightness decreased in all samples as the fermentation period and garlic concentration increased. Yellow index decreased in weeks 5~6 compared with weeks 0-1, for which the values were lower for the garlic-added Doenjang than the control. The pH increased, greatly reducung the acidity in week 1 compared with week 0. Significant differences in the pH and acidity were not observed among the sample groups. Amino type nitrogen contents increased continuously up to weeks 5, displaying no significant differences among the sample groups at weeks 5 and 6. In addition, reduction in the sugar content increased depending on the fermentation period. It increased in all sample groups by about 2.5 times after 6 weeks compared with the initial levels. Isoflavone content was also reduced generally depending on the fermentation period. In the early fermentation periods, the aglycone contents were the higher than the glycosides, while the glycoside contents increased over the fermentation period. The presence of Bacillus was not significantly different among the garlic added groups, but yeast was lower in the Doenjang with high garlic content.

Bitter gourd (Momordica charantia L.) fruit has long been used as a food and medicine in tropical and subtropical regions. The purpose of this study was to investigate total vitamin C content, total phenolic content, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, 2,2′-zinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging (ABTS) assay and ferric reducing antioxidant power (FRAP) assays in 8 cultivars of bitter gourd in plastic greenhouse located in Jeju Island, Korea. Fruit length and fruit weight ranged from 7.1±0.5 to 37.0±1.9 cm and from 18±2 to 577±95 g, respectively at harvest time. The contents of total vitamin C (112.4±12.0 mg/100 g) and total phenolic content (3.81±0.3 mg/g) were higher in 'Nakanokoya' cultivar (large fusiform fruits) compared to other cultivars (long and small fruits) tested bitter gourd. The DPPH, ABTS and FRAP assays tends to higher in 'Nakanokoya' and 'Kanzyukoya' cultivars than others bitter gourd cultivars. Therefore, eNakanokoya f bitter gourd was the highest in content of vitamin C and antioxidant activities among experimented cultivars in greenhouse cultivation.

In this study, the characteristics of alcohol fermentation using Elaeagnus multiflora juice were studied under static fermentation condition in an effort to develop new types of functional wine. After 9 days of fermentation at 25^{\circ}C, the pH, soluble solids, reducing sugar, viable cell numbers, and alcohol contents were shown to be 3.32~3.33, 7.8{\sim}9.0^{\circ}C, 29.84~31.05 g/L, 7.26~8.73 cfu/mL, and 11.0%, respectively. The heat treated juice exhibited significantly higher antioxidant activity than untreated juice while the soluble phenolic and flavonoid contents became higher. Also, the fermented wine after the heat treated at 120^{\circ}C for 30 min contained free sugar such as fructose (0.42 g/L) and glucose (0.09 g/L), major organic acids such as lactic acid (7.32 g/L), malic acid (2.59 g/L), succinic acid (2.16 g/L), and oxalic acid (3.08 g/L), and major flavanols and phenolic acids such as catechin (99.45 mg/L), epicatechin (264.55 mg/L), epigallocatechin (82.19 mg/L), gallic acid (6.44 mg/L), and salicylic acid (60.53 mg/L). In addition, DPPH radical and ABTS radical scavenging activities and FRAP assay results were 70.47%,, 65.93%, and 1.254, respectively. These results suggest that it is possible to produced a new type of wine using Elaeagnus multiflora fruits.

This study was performed to determine the optimal composition of Cheonggukjang added with garlic. The experiment utilized a central composite design (CCD). The evaluation was carried out by means of response surface methodology (RSM), which included 18 experimental points with three independent variables : the content of the garlic (1.3~9.7%, ), the steaming time of garlic (0~15.1 min, ), and the fermentation time of Cheonggukjang (48.2~71.8 h, ). The viscous substance (), acidity (), amino-type nitrogen (), -GTP activity () and ABTS radical scavenging activity (). were assessed in four replicates with five dependent variables. The maximum content of the viscous substance was 13.02% at 6.53% (), 6.81 min () and 55.18 h (). The acidity was increased when the fermentation time was longer, and the minimum acidity point was 0.50% at 7.75% (), 3.42 min () and 58.60 h (), respectively. The content of the amino-type nitrogen at the experimental range studied was was 80.58~158.82 mg%, and the stationary point was at saddle point. Using ridge analysis, the maximum point was 156.97 mg% at 6.21% (), 14.85 min () and 58.04 h(). The optimum conditions of -GTP activity was 5.73% (), 6.99 min () and 57.96 h(), respectively, at the maximum point was 353.66 mU/mL. The maximum point of ABTS radical scavenging activity was 76.43% at 3.78% (), 14.28 min () and 57.99 h() at the saddle point, when the garlic steaming time was longer.

For the production of Korea traditional cereal wine makgeolli, a rice fermentation starter nuruk was Rhizopus oryaze CCS01 commercial nuruk. The carbohydrate content of rice nuruk was higher, the levels of moisture, ash, crude protein, and crude fat were lower. In particular, the saccharifying activity of rice nuruk was 2.2 times higher than commercial nuruk. pH, alcohol, and viable yeast cells of makgeolli made rice nuruk were higher than those of makgeolli made commercial nuruk. In contrast, the levels of acidity, , viable lactic acid bacteria (LAB) cells, and browning of makgeolli made rice nuruk were lower than those of makgeolli made commercial nuruk, the alcohol content of glutinous rice (GUR) makgeolli made rice nuruk higher other samples. These results suggest that rice nuruk R. oryzae CCS01 make new type cereal makgeolli.

We previously reported that the truncated Cel44C- -glycosyl hydrolase protein exhibits multifunctional activities, including cellulase, xylanase, and lichenase. DNA shuffling of the truncated Cel44C- enzyme was performed to enhance the enzymatic activity of the multifunctional -glycosyl hydrolase. Two mutant enzymes, M2Cel44C- that carries one mutation (P438A) and M21Cel44C- that carries two mutations (A273T and P438A) were obtained. The enzymatic activity of the M21Cel44C- double mutant was lower than enzymatic activity of the single mutant (M2Cel44C-). However, both mutants displayed the enhancements in their enzyme activities that were - to 2.2-fold higher than the original enzymatic activity in Cel44C-. In particular, the mutant M2Cel44C- exhibited an approximate 1.5- to 2.2-fold increase in the cellulase, xylanase, and lichenase activities in comparison with the control (Cel44C-). The optimum cellulase, linchenase, and xylanase activities of -glycosyl hydrolase were observed at pH 7.0, pH 7.0 and pH 6.0, respectively. These results, therefore, suggest that the amino acid residue Ala438 plays important roles in the enhancement of the activity of multifunctional -glycosyl hydrolase.

To improve of the quality of Korea traditional wheat-rice wine (makgeolli) production, we used a rice fermentation starter (rice nuruk) made by inoculation of Rhizopus oryzae CCS01 which was isolated and selected from commercial nuruk. Amylase activity of a rice nuruk was 1.8-2.4 times higher than those of commercial nuruks. The best acceptability of wheat-rice wine in a sensory test was observed at 4 : 6 ratio of wheat-rice mash at experimental condition. During the fermentation period, pH of wheat-rice makgeolli made with a rice nuruk was higher compared to those made with commercial nuruks such as Sanseong, Jinju, and Songhak. Acidity of makgeolli mash was lower in case of using a rice nuruk and birx and alcohol production were higher compared to those of makgeolli mash using commercial nuruks. Highest alcohol production was observed at makgeolli mash using a rice nuruk and 12% of alcohol was produced at fermentation end. These results suggest that production of a new type of wheat-rice makgeolli using a rice nuruk was possible.