• Preventive Nutrition and Food Science
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• v.9 no.2
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• pp.113-120
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• 2004

Selected microbiological and biochemical characteristics of the steeping process for the production of yukwa, a traditional Korean oil-puffed snack made of waxy rice, were investigated during steeping of waxy rice in water for 15 days. The lengthy steeping process was largely predominated by lactic acid bacteria (LAB), particularly, Lactobacillus and Leuconostoc. The predominat type of bacterium isolated was the Y26 strain tentatively identified as Lactobacillus plantarum. The titratable acidity of the steeping medium increased from 0.01 to 1.13%, in parallel with the decrease in pH ranging from 6.3 to 4.2 as the steeping period increased from 0 to 15 days. A high amount of lactic acid and to a much lesser extent, butyric acid, acetic acid, propionic acid, and succinic acid were detected during the steeping process. The amount of reducing sugars in the steeping medium increased from 0.61 to 10.43 mg/mL, whereas sucrose decreased from 0.46 mg% to an undetectable level. Starch degradation products including glucose, maltose and oligosaccharides ranging G3-G7 were not initially noticed, but their content increased during the steeping process until completion. However, no oligosaccharides larger than G8 were detected in the steeping medium. The activities of $\alpha$-amylase, $\beta$-amylase and protease in the steeping medium of waxy rice tended to rise increase with time during the steeping process. From these results, the lengthy steeping process in yukwa production can be characterized as the spontaneous fermentation, dominated by lactic acid bacteria, which is a necessary process for inducing biochemical modification of waxy rice.

• Journal of The Korean Society of Grassland and Forage Science
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• v.37 no.1
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• pp.10-18
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• 2017

A total of nine Korean indigenous goats were used in a cross-over arrangement to give nine replicates per treatment, and they were housed individually assigned to 1 of 9 dietary treatments. Nine treatments were 0, 500, and 1000 ppm of quercetin supplementation in diets by mixing roughage and concentrate with different ratios (RC ratio) of 3:7 (RC 30), 5:5 (RC 50) and 7:3 (RC 70). Nutrient utilizations of dry matter, crude fat and NDF were not affected by neither RC ratio nor dietary quercetin (p>0.05), but the rate of crude protein and ADF increased in animals in RC 70 group regardless of quercetin supplementation (p<0.05). In addition, higher RC ratio increased (p<0.05) N retention and N retention rate. Total VFA, acetic acid, propionic acid, iso-butyric acid, butyric acid, iso-valeric acid and valeric acid contents were not affected (p>0.05) by dietary quercetin. Meanwhile, lower total cholesterol level exhibited in animals in RC 70 group compared to RC 30 or 50 groups, unrelated to dietary quercetin (p<0.05), however other plasma parameters were not influenced (p>0.05) by RC ratio and dietary quercetin. Our results indicated that both RC ratio and dietary quercetin may not directly affect the production indices and immune responses in Korean indigenous goat.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.10
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• pp.672-678
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• 2014

In this study, variations of fermentative hydrogen production and microbial community were investigated with different nitrogen concentration of food waste. Optimum hydrogen production rate was acquired at 200 mg/L nitrogen concentration of the food waste. Which was eqivalent to 83.43 mL/g dry biomass/hr. However, bio-hydrogen production was inhibitedly reduced at over 600 mg/L of nitrogen concentration whereas proportional relation between hydrogen production and B/A ratio were not observed. Most dominant specie of the microbial community analyzed was Clostridium sp. throughout PCR-DGGE analysis of 16S rDNA. It revealed that most contributing microorganism producing hydrogen were Enterococcus faecium partial, Klebsiella pneumoniae strain ND6, Enterobacter sp. NCCP-231, and Clostridium algidicarnis strain E107 in this experiment.

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.1085-1090
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• 2002

Leuconostoc mesenteroides, the major bacterium in the initial phase of lactate-fermentation in kimchi, produces lactic acid, acetic acid, mannitol, and $CO_2$. It also secrets dextransucrase, which catalyzes the transfer reaction of glucose from sucrose to maltose, synthesizing mainly panose ($6^_2-{\alpha}-D-glucopyranosylmaltose)$, a probiotic oligosaccharide. To use the strain as a starer culture to produce high amount of panose during kimchi fermentation, we screened psychrotrophic strains showing fast growth rate at low temperature among the isolates of Leuconostoc sp. and selected two strains showing high dextransucrase activity. The strains were identified as Leuconostoc mesenteroides, which can be used as function added-starters for lactate-fermented foods.

• New & Renewable Energy
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• v.19 no.4
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• pp.35-45
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• 2023

Global efforts are focused on achieving carbon neutrality due to the increases in the levels of greenhouse gases. Moreover, the greenhouse gases generated from the disposal of municipal solid waste (MSW) are the primary sources of emissions in South Korea. In this study, we conducted the biological conversion of syngas (CO, H₂, and CO₂) generated from MSW gasification. The MSW-derived syngas was used as a feed source for cultivating Eubacterium limosum KIST612, and pressurization was employed to enhance gas solubility in culture broth. However, the pH of the medium decreased owing to the pressurization because of the CO₂ in the syngas and the cultivation-associated organic acid production. The replacement of conventional HEPES buffer with a phosphate buffer led to an approximately 2.5-fold increase in acetic acid concentration. Furthermore, compared with the control group, the pressurized reactor exhibited a maximum 8.28-fold increase in the CO consumption rate and a 3.8-fold increase in the H2 consumption rate.

• Journal of Practical Agriculture & Fisheries Research
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• v.25 no.4
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• pp.127-137
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• 2024

This study was conducted to investigate effect of corn flake and corn ground on nutrient digestibility and fermentation characteristics of rumen in Hanwoo. The animals used were three Hanwoo cows implanted with ruminal fistula. Corn were categorized in 2 groups based on the corn processing method: Ground and Flake. The rumen digestibility of dry matter, starch, nitrogen free extract and non fiber carbohydrates were increased in flake compared to ground from 3 to 24 hours of incubation(P<0.05). The pH of rumen was lower in the flaked treatment than ground treatment at 3 hours after incubation, but average pH was no significantly difference between treatments. The average acetic acid, propionic acid and butyric acid were significantly increased in the flaked treatments compared to the ground treatment (P<0.05). Thus, flake processing can improve the carbohydrate availability of corn in the rumen and increase feed value.

• Korean Journal of Food Science and Technology
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• v.26 no.1
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• pp.12-17
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• 1994

Physicochemical characteristics of traditional kochujang fermented for 6 months and commercial kochujang were compared. Tested kochujang included 18 kinds of Sunchang kochujang prepared with glutinous rice, 10 kinds of Boeun kochujang prepared with barley and 17 kinds of Sachun kochujang prepared with wheat, and 10 kinds of commercial kochujang. Major free sugar was found to be glucose both in traditional and commercial kochujang. Fructose, maltose, and sucrose were also detected in small amounts. The contents of free sugars in traditional kochujang was approximately one fourth of those presented in commercial kochujang. Commercial kochujang showed the highest level of total free amino acids followed in decreasing order by Sachun, Sunchang, and Boeun kochujang. The most abundant free amino acid was serine in Sunchang kochujang and aspartic acid both in Boeun and Sachun kochujang. On the other hand, glutamic acid was the most abundant amino acid in commercial kochujang. Volatile organic acids in various kochujang were determined and acetic, propionic, butyric, and 3-methyl butanoic acids were found in traditional kochujang. However, 3-methyl butanoic arid was not found in commercial kochujang. The most abundant volatile acid was acetic acid in both tradtional and commercial kochujang. Analysis of non-volatile organic acids showed that large amounts of lactic, oxalic, and succinic acids were found in traditional and commercial kochujang. In addition to these, small amounts of itaconic, malic, malonic, and pyroglutamic acids were found in commercial kochujang.

• Korean Journal of Food Science and Technology
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• v.47 no.5
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• pp.579-585
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• 2015

Following supplementation with organic acids (acetic, citric, and lactic acids), the pH of the alcohol mash changed from 4.2 control to 3.73-3.97 supplemented, the acidity from 5.06 to 8.13-9.98, and the alcohol content from 17.8 to 17.0-17.8%. Protease activity decreased owing to the pH change, and the total nitrogen content decreased by 13.1-36.9% following organic acid supplementation. Organic acid supplementation did not affect the distillation efficiency; however, thiobarbituric acid values in the crude distillate (40%) decreased 2.2-3.6 fold following supplementation with citric acid and lactic acid. The total isobutanol (B), isoamyl alcohol (A), and 1-propanol (P) contents in each soju (25%) supplemented with organic acid were 1,041.47, 979.50, and 961.48 ppm, respectively, which were higher than those in the control soju (935.27 ppm). The A/P, A/B, and B/P ratios of soju were altered and the acetaldehyde content decreased following supplementation with the organic acid.

• Korean Journal of Food Science and Technology
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• v.43 no.5
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• pp.570-576
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• 2011

The effect of nuruks and crude amylolytic enzyme on free amino acid and volatile components of brown rice vinegar prepared by static cultures was investigated. Five groups consisted of AV (100% nuruk without crude amylolytic enzyme), BV (75% nuruk; 25% crude amylolytic enzyme), CV (50% nuruk; 50% crude amylolytic enzyme), DV (25% nuruk; 75% crude amylolytic enzyme) and EV (100% crude amylolytic enzyme without nuruk). Free amino acid content in AV vinegar (132.06 mg%) was lower than the others (184.56-191.22 mg%). Acetic acid, 3-methyl butyl acetate, acetoin and isoamyl alcohol were major volatile components as analyzed using gas chromatography-mass spectrometry after headspace solid-phase microextraction. Acetic acid in AV and EV samples represented 67.56% and 55.53% of total GC peak area, respectively. E-nose provided different patterns in each case showing variation in sensory properties.

• Korean journal of food and cookery science
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• v.7 no.1
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• pp.15-25
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• 1991

The effects of lactic acid bacteria on the chemical and microbial changes of fermented kimchi at various temperatures were studied. Kimchi was homogenized and was sterilized by ultra violet, then Lactobacillus plantarum, Leuconostoc mesenteroides, Pediococcus acidilactici, Lactobacillus brevis and the mixture of there bacteria inoculated on sterilized kimchi, respectively. The measurement of pH and total acidity, quantitative analysis of volatile organic acids and nonvolatile organic acids by gas chromatography were investigated while inoculated kimchi were fermented at $30^{\circ}C$, $21^{\circ}C$, $14^{\circ}C$ and $7^{\circ}C$. Sample I (original kimchi homogenate), Sample III (inoculated with Leuconostoc mesenteroides) and Sample Ⅵ (inoculated with mixed lactic acid bacteria) were alike in that changes of pH and total acidity and especially, these phenomena were prominent at $14^{\circ}C$. Formic, acetic and heptenoic acid as volatile organic acid were detected by GC, and these acids formed mainly by Leuconostoc mesenteroides and lactobacillus brevis. Sample III was more higher content than other samples at $14^{\circ}C$. As nonvolatile organic acid, lactic acid in all samples, citric acid in sample III at $21^{\circ}C$and $14^{\circ}C$, succinic acid in sample I at $30^{\circ}C$, $21^{\circ}C$, $14^{\circ}C$ and sample V at $30^{\circ}C$ were detected by GC.