• Journal of Microbiology and Biotechnology
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• v.22 no.12
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• pp.1782-1789
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• 2012

We have developed a novel type of polymer nanogel loaded with anticancer drug based on bio-derived poly(${\gamma}$-glutamic acid) (${\gamma}$-PGA). ${\gamma}$-PGA is a highly anionic polymer that is synthesized naturally by microbial species, most prominently in various bacilli, and has been shown to have excellent biocompatibility. Thiolated ${\gamma}$-PGA was synthesized by covalent coupling between the carboxyl groups of ${\gamma}$-PGA and the primary amine group of cysteamine. Doxorubicin (Dox)-loaded ${\gamma}$-PGA nanogels were fabricated using the following steps: (1) an ionic nanocomplex was formed between thiolated ${\gamma}$-PGA as the negative charge component, and Dox as the positive charge component; (2) addition of poly(ethylene glycol) (PEG) induced hydrogen-bond interactions between thiol groups of thiolated ${\gamma}$-PGA and hydroxyl groups of PEG, resulting in the nanocomplex; and (3) disulfide crosslinked ${\gamma}$-PGA nanogels were fabricated by ultrasonication. The average size and surface charge of Dox-loaded disulfide cross-linked ${\gamma}$-PGA nanogels in aqueous solution were $136.3{\pm}37.6$ nm and $-32.5{\pm}5.3$ mV, respectively. The loading amount of Dox was approximately 38.7 ${\mu}g$ per mg of ${\gamma}$-PGA nanogel. The Dox-loaded disulfide cross-linked ${\gamma}$-PGA nanogels showed controlled drug release behavior in the presence of reducing agents, glutathione (GSH) (1-10 mM). Through fluorescence microscopy and FACS, the cellular uptake of ${\gamma}$-PGA nanogels into breast cancer cells (MCF-7) was analyzed. The cytotoxic effect was evaluated using the MTT assay and was determined to be dependent on both the concentration and treatment time of ${\gamma}$-PGA nanogels. The bio-derived ${\gamma}$-PGA nanogels are expected to be a well-designed delivery carrier for controlled drug delivery applications.

• Food Science of Animal Resources
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• v.29 no.6
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• pp.659-667
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• 2009

Casein is considered to be the main source of protein in milk; therefore, many studies have been conducted to identify casein-derived bioactive peptides and their physiological effects. Casein is inactive within the parent protein but can be liberated by various proteases and enzymatic hydrolysis during microbial fermentation and gastrointestinal digestion. Once absorbed, casein exhibits different bioavailabilities in the body. Specifically, casein-derived peptides function as angiotensin converting enzyme (ACE) inhibitor in the cardiovascular system; thus, they are expected to reduce and prevent hypertension. Additionally, casein-derived peptides behave as opioid-like peptides in the nervous system, which impacts relaxation. These peptides are also expected to modulate various aspects of immune functions. Finally, caseinophosphopeptide (CPP) and glycomacropeptide (GMP) may exhibit a number of nutritional effects such as the absorption of calcium, iron or zinc. Many studies have been conducted to evaluate casein-derived peptides due to their multifunctional properties and the results of these studies have contributed to the development of a wide variety of functional dairy products. The purpose of this paper was to review the generation of bioactive peptides, their absorption and metabolism, and their specific bioactive effects.

• Food Engineering Progress
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• v.14 no.4
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• pp.346-353
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• 2010

Due to the globalization of Korean foods, there are great interests in traditional Korean foods. Thus, the enhancement and development of makgeolli processing have been constantly accomplished. In case of makgeolli, the storage stability is very important because the fermentation of makgeolli during distribution is still progressed. Therefore, the objective of this study was to investigate storage stability of makgeolli by separation storage methods. During the 30-day storage at $10^{\circ}C$, pH value, titratable acidity, color value, sugar content, reducing sugar content, and alcohol content were measured. Microbial cell counts were also evaluated. Reducing sugar content was decreased after 10 days for all the samples. In the case of titratable acidity and color, these values were constantly increased with storage time. Especially, the yellowness value of the precipitate of makgeolli was increased by two times than that of the beginning. There was a decreasing tendency for lactic acid bacteria with storage time. In case of yeast, there was a decreasing tendency after 15 days, but the significance was not detected. The quality changes in the samples from centrifugal separation were relatively less than the control. Therefore, the separation storage method could affect the enhancement of makgeolli quality during distribution.

• Journal of the Korean Society of Food Culture
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• v.34 no.2
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• pp.224-232
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• 2019

This study evaluated the physicochemical and microbial quality characteristic of seasonal commercial kimchi for hygienic safety levels. The pH of seasonal commercial kimchi was 3.84-6.36 and the titratable acidity and salinity of the samples were 0.21-1.16 and 1.19-1.54%, respectively. The content of nitrate and nitrite in the commercial kimchi were lower in the spring and summer, which was affected by acidic condition of the kimchi depending on fermentation. Heavy metal contents in commercial kimchi are not an issue because they were detected only at very low levels. The total aerobic bacteria and coliforms counts ranged from 5.25 to 8.44 Log CFU/g and 0.00 to 5.08 Log CFU/g, respectively. The total aerobic bacteria and coliforms were detected more in summer than in the other seasons. E. coli was detected in three of the samples tested. Food-borne pathogens were not detected in any of the samples except for B. cereus. B. cereus was detected in the fall in more than 70% of samples. These results suggest that commercial kimchi distributed in the fall maintain the quality properties and the microbiological safety of kimchi compared to the other seasons. Therefore, further studies as an effective distribution system for the particular seasons will be needed to guarantee the hygienic safety levels of commercial kimchi required by the consumers.

• Food Science and Industry
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• v.53 no.1
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• pp.69-83
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• 2020

For the development of the chitosan industry in Korea, the catch of red snow crabs caught on the east coast is rapidly decreasing. Therefore, it is urgent to develop raw materials that can replace the red snow crab as the top priority to solve the supply and demand problems, as well as wastewater treatment costs account for a large proportion of the cost of chitosan. In order to solve the problems, continuous research on biological extraction methods such as enzymatic extraction and microbial fermentation will increase production efficiency and lower unit cost as well as chemical extraction methods. Further efficient manufacturing method can be established. Establishing of novel techniques is indispensable for production of high-purity chitosan and the ability to regulate and separate the molecular weight, as well as joint research with industry, academia and research institute for the research and development of high-functional chitosan derivatives.

• Microbiology and Biotechnology Letters
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• v.50 no.1
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• pp.135-146
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• 2022

Obesity is closely associated with profound dyslipidemia, insulin resistance, and fatty liver disease. Recent reports have suggested that alterations in gut microbiota can be linked to diet-induced obesity. In this study, the anti-obesity effects of Weissella confusa WIKIM51 isolated from kimchi were investigated, as evidenced by: i) reduced lipid accumulation and downregulated adipogenesis-related genes in 3T3-L1 adipocytes; ii) suppressed gains in body weight and epididymal fat mass; iii) reduced serum lipid levels, for example, triglyceride and total cholesterol; iv) increased serum adiponectin levels and reduced serum leptin levels; v) downregulated lipogenesis and upregulated β-oxidation-related genes in the epididymal fat; and vi) altered microbial communities. The collective evidence indicate the potential value of W. confusa WIKIM51 as a functional food supplement for the prevention and amelioration of obesity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.5
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• pp.721-728
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• 2005

The physicochemical and microbial characteristics of pickled cucumber prepared with dry salting method, which has been used for industry, were investigated. Salting and storage conditions were HSHT $(30\%,\;25^{\circ}C)$, MSMT $(21\%,\;15^{\circ}C)$, MSLT $(21\%,\;0^{\circ}C)$, LSMT $(15\%,\;15^{\circ}C)$ and LSLT $(15\%,\;0^{\circ}C)$. Acidity was lower, and pH was higher in higher salt concentration as well as lower temperature groups. At the storage of 165 days, acidity and pH reached to $0.21\%$ and 4, respectively in MSLT and HSHT, of which conditions fermentation was retarded, compared to the other groups. During storage of pickled cucumber, greenness (-a) of Hunter color system showed the highest in MSLT ranged from -10.70 to -8.08, while in LSMT, the lowest to 1.17. Total microbial and lactic acid bacteria number in HTST and MSLT were the lowest than in other groups, while tile highest in LSMT. Yeast was not detected in HSHT and MSLT after 36 days of storage, while higher in LSMT Texture profile analysis exhibited that fracturability (2,318 g and 2,318 g) and hardness (849 g and 702 g) were highest in HSHT and MSLT, compared to the other groups. Scores of over-all preference for MSLT and LSLT were higher with 8.8 and 7.6, respectively, compared to the other products (p<0.05). Based on these results, lower saltiness and lower storage temperature condition was better for pickled cucumber preparation in industry.

• Food Science of Animal Resources
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• v.30 no.3
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• pp.435-442
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• 2010

The study analyzed the effects of salt concentration [high salt (HS) and low salt (LS)] and sodium nitrite ($NaNO_2$), which are typically utilized in Korean processing facilities, on fatty acid composition, free amino acids, microbial counts and sensory characteristics of processed dry-cured ham. Four different treatments were considered: three hams (11.30 kg) salted with 92 g/kg salt (w/w) (HS), three hams (10.65 kg) treated with HS and 100 ppm $NaNO_2$ (HS+$NaNO_2$), three hams (11.42 kg) salted with 62 g/kg salt (w/w) (LS), and three hams (10.62 kg) treated with LS and 100 ppm $NaNO_2$ (LS+$NaNO_2$). Fatty acid composition analysis revealed significantly (p<0.05) higher saturated fatty acid and lower (p<0.05) unsaturated fatty acid in the HS+$NaNO_2$ group compared with the other groups. Glutamate, alanine and lysine free amino acids were higher than the other free amino acids. The processing conditions did not significantly affect the free amino acids of biceps femoris muscles, except for the proline content (p>0.05). In sensory evaluation, the fermentation aroma of the LS group was higher than that of the HS group. The aerobic counts consistently ranged from from $2.3{\times}10^2$ to $1.11{\times}10^4$ CFU/g. Escherichia coli including strain O157:H7, Staphylococcus aureus, and Salmonella spp. were not detected.

• Journal of The Korean Society of Grassland and Forage Science
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• v.42 no.4
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• pp.229-236
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• 2022

This study was conducted to evaluate the efficacy of adding the microbial inoculants to silage for reducing mycotoxins in rice straw silage. When a single agent of L. plantarum and a mixed agent of L. plantarum and S. cerevisiae were added in rice straw silage contaminated mycotoxins, it had an effect on silage fermentation and fiber degradation as well as mycotoxin reduction. Among the mycotoxins, only ochratoxin A and zearalenone were found in the test sample. Ochratoxin A and zearalenone showed a decreasing trend with the addition of silage inoculants compared to the control groups (38.11±2.22 and 633.67±50.30 ㎍/kg), and there was a significant difference at the mixed agents; 27.78±2.28 and 392.72±25.04 ㎍/kg, respectively (p<0.05). The pH was lower in the single agent and the mixed agent compared to the control (p<0.05). The concentration of lactic acid was higher in the single agent (11.73±0.31 mM) than in the control group (8.18±0.93 mM), and the highest concentration was 16.01±0.88 mM in the mixed agent (p<0.05). Acetic acid and propionic acid were found to be significantly lowered with the addition of silage inoculants (p<0.05). Total VFA was also lower at the addition of silage inoculants than the control group (p<0.05). The rumen in situ dry matter degradation of NDF and ADF was maintained at the highest levels of the mixed agent during the culture period, followed by the single agent and the control group at the lowest level. NDF and ADF degradation showed a significant difference at all time points after 12 and 24 hours of culture, respectively (p<0.05). The study results showed that the silage inoculants had the positive effects on quality increasing of rice straw silage; fermentative charateristics, fiber degradation and mycotoxins reduction. Ochratoxin A and zearalenone were greater reduction by adding bacterial inoculants of silage. Therefore it is considered that L. plantarum and S. cerevisiae will improve the quality and stability with remediation of mycotoxin in silage.

• Korean Journal of Environmental Agriculture
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• v.34 no.2
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• pp.91-97
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• 2015

BACKGROUND: Earthworms are essential detritus feeders that play a vital role in the process of decomposition of organic matter and soil metabolism. The complex process of partial breakdown of organic matter and mixing with mucous and gut microbial flora in the form of earthworm cast results in the reduction of the toxicity. This study focused on the change of cast amount and pollutant contents before and after the eating of the organic waste and upland soil with the two species of earthworm. METHODS AND RESULTS: The two species of earthworms were compared to the cast production. In the upland soil material, the daily amount of worm's cast was 1.42 g in E. andrei and 0.40 g in A. agrestis. In the organic waste material, the cast of E. andrei was 0.78~0.83 g and the cast of A. agrestis. have not been collected because all earthworms died after the treatment. The heavy metals treated in the upland soil were evaluated the impact of the worm excretion. With the E. andrei, the cast production was decreased 0.1~0.8 times in zinc, 0.2~0.5 times in copper, and 0.1~0.7 times in cadmium compared to the control treatment according to the levels of concentration. With A. agrestis, the cast amount was decreased 0.3~1.1 times in zinc, 0.2~0.3 times in copper, and 0.1~2.1 times in cadmium, respectively. The changes of pollutant contents before and after the eating of the organic wastes with E. andrei were studied. In the treatment of the Alcohol Fermentation Processing Sludge and the Fruit Juice Processing Sludge, heavy metal content of the cast was increased 0.7~53.3% compared to the sludge materials. PAHs contents were decreased 50.1% in the cast of the Alcohol Fermentation Processing Sludge and 36.6% in the cast of the Fruit Juice Processing Sludge, respectively. CONCLUSION: In conclusion, although the A. agrestis was bigger than E. andrei in size and weight, the cast amount of A. agrestis was small. The two species of earthworm was less excretion with high concentration of heavy metals. While the heavy metals such as zinc, copper, and cadmium were considerably accumulated in the cast, the total compounds, PAHs were fairly decomposed. There results would provide us for restoring contaminated soil and cleaning organic wastes.