• Korean journal of food and cookery science
• /
• v.29 no.6
• /
• pp.671-677
• /
• 2013

The objective of this study was to examine the levels of free amino acids and identify the correlation between ${\gamma}$-aminobutyric acid (GABA)and L-glutamic acid contents in Kimchi during fermentation. During 2 weeks of fermentation, the acidity of Kinchi increased, i.e., the pH level decreased from 5.24 to 4.40. The content of amino acids determined using HPLC differed significantly (p < 0.05) during 7 weeks of fermentation. Over the 7 weeks of fermentation, the content of most free amino acids increased in the order L-valine > L-glutamic acid > L-glycine, except L-methionine decreased. Initially, the GABA content was found to be $72.43{\mu}M/100g$ fresh weight (fw), and it increased to $229.06{\mu}M/100g$ fw after 7 weeks. This rapid increase in the GABA content in the initial stage is considered to be due to L-glutamic acid. However, during the period of 0~7 weeks, no correlations were found between the L-glutamic acid and GABA contents.

• Journal of Microbiology and Biotechnology
• /
• v.9 no.5
• /
• pp.593-603
• /
• 1999

Poly(3-hydroxybutyrate) (PHB) production by fermentation was examined under both restricted- and ample-oxygen supply conditions in a single fed-batch fermentation. Recombinant Escherichia coli transformed with the PHB production plasmid pSYLl07 was grown to reach high cell density (227 g/l dry cell weight) with a high PHB content (78％ of dry cell weight), using a glucose-based minimal medium. A simple flux model containing 12 fluxes was developed and applied to the fermentation data. A superior closure (95％) of the carbon mass balance was achieved. When the data were put into use, the results demonstrated a surprisingly large excretion of formate and lactate. Even though periods of severe oxygen limitation coincided with rapid acetate and lactate excretion, PHB productivity and carbon utilization efficiency were not significantly impaired. These results are very positive in reducing oxygen demand in an industrial PHA fermentation without sacrificing its PHA productivity, thereby reducing overall production costs.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.20 no.6
• /
• pp.565-571
• /
• 1991

A short time microwave heat treatment, bringing in hot NaCl solution, addition of KCI, CaCl2, MgCl2 into brining solution and salts mixture of phosphates into half fermented dongchim were investigated for their effects on some quality of dongchimi, a Korean pickle of Chinese radish roots, during fermentation. The reference dongchimi was prepared by brining the radish roots in 7% NaCl added with seasonings at $25^{\circ}C$. The result showed that microwave heat treatment affected little on the pH or total acidity change during fermentation. Soaking the roots in 80-9$0^{\circ}C$ hot salt solution significantly reduced the fermentation and softening rate of dongchimi while a rather rapid fementation was found for those soaked in 7$0^{\circ}C$. Addition of KCI and CaCl2 into brining solution slowed the pH decrease and softening of the roots, respectively. The dangchimi added with the salts mixture of phosphate, citrate and nitrite was significantly extreneded the fermentation time to pH 4.0 by more than two folds.

• Korean journal of food and cookery science
• /
• v.27 no.5
• /
• pp.577-587
• /
• 2011

In this study, lotus leaf was added to a Takju (Korean milky rice wine) preparation to evaluate its effects on physicochemical and fermentation properties. For rapid saccharification Takju was stored at 25$^{\circ}C$ for 2 days and then temperature was switched to 18$^{\circ}C$ to mature the wine for 21 days. From the start of fermentation to 2-days, the pH of Takju decreased rapidly and acidity increased. Maltose, a byproduct of starch saccharification, increased for 2 days then rapidly decreased. Glucose fluctuated for 7 days and of the 21-days fermentation. The ethanol production rate was highest during the first 7 days, then slowed. Total viable yeast and lactic acid bacterial counts increased rapidly for 2 days and then decreased gradually thereafter. Leuconostoc spp. grew rapidly for 1 day and sharply disappeared with decreasing pH. DPPH radical scavenging activity was significantly higher for Takju prepared with lotus leaf than without. The overall acceptance of Takju tended to increase when it was prepared with lotus leaf.

• The Korean Journal of Mycology
• /
• v.11 no.4
• /
• pp.177-181
• /
• 1983

To improve cultivation technique for the stable and high yield, the outdoor fermentation of rice straw bundles, and pasteurization and fermentation of rice straw compost in tunnel were carried out. 1) Mycelial growth of P. ostreatus was becoming rapid and dense according to prolongation of fermentation periods outdoor rice straw bundles, but days untill fully mycelial growth after spawning was short. 2) As the fermentation period of rice straw bundles was 6 days (three times turning), yield of P. ostreatus was the highest as $50.5kg/3.3m^2 and increased 24% of yield than those of conventional method. 3) When it was fermented rice straw compost in tunnel for 4 days, mycelial growth of P. ostreatus was rapid and dense, and also days untill budding after spawning, was shorter, yield $67.6kg/3.3m^2$, resulted in increasing 17% of yield than those of conventional method. 4) On being sterilization and fermentation of the rice straw compost in tunnel, the production cost was decreased 22.3% in compared with conventional method.

• Korean journal of food and cookery science
• /
• v.15 no.1
• /
• pp.61-67
• /
• 1999

The effects of salting methods on Kakdugi (cubed radish kimchi) fermentation were evaluated. Kakdugi was prepared with various salting methods, salt concentrations, and settling times, and fermented at 10$^{\circ}C$ for up to 52 days. Radish (Raphanus sativus L.) cubes (2 cm size) were salted by using the following methods salt concentration of about 1.5% which was known appropriate for the organoleptic quality of Kakdugi: 1) Treatment S-1: applying dry salt uniformly onto the radish cubes, with a salt concentration of about 1.5% (w/w) and cured for 1 hr, 2) Treatment S-5: applying dry salt uniformly onto the radish cubes, with a salt concentration of about 1.2% (w/w) and cured for 5 hr, 3) Treatment B-1: brining radish cubes in a 8.5% (w/v) salt solution for 1 hr, 4) Treatment B-5: brining radish cubes in a 4.0% (w/v) salt solution for 5 hr. As the fermentation continued, the initial high decrease in pH has been retarded in all the treatments, of which the delaying extent was more significantly noted from B-1 and B-5 than S-1 and S-5. The pH of the Kakdugi which showed a good eating quality dropped to 4.3∼4.8 with the accumulation of total acids. Total vitamin C increased sharply at the palatable period of Kakdugi during the initial fermentation and then decreased gradually following a sigmoidal changing pattern. The reducing sugar levels were also influenced by salting methods and fermentation as sugars are converted into acids. High initial contents of reducing sugars and their subsequent rapid decrease were observed in “S” group than “B” group during fermentation. For nonvolatile organic acids, lactic acid increased consistently throughout the fermentation while malic acid, which was high at the initiation of fermentation, decreased rapidly afterwards at the palatable period of Kakdugi.

• Journal of Ginseng Research
• /
• v.41 no.1
• /
• pp.36-42
• /
• 2017

Background: Some differences have been reported in the biotransformation of ginsenosides, probably due to the types of materials used such as ginseng, enzymes, and microorganisms. Moreover, most microorganisms used for transforming ginsenosides do not meet food-grade standards. We investigated the statistical conversion rate of major ginsenosides in ginsenosides model culture during fermentation by lactic acid bacteria (LAB) to estimate possible pathways. Methods: Ginsenosides standard mix was used as a model culture to facilitate clear identification of the metabolic changes. Changes in eight ginsenosides (Rb1, Rb2, Rc, Rd, Re, Rf, Rg1, and Rg2) during fermentation with six strains of LAB were investigated. Results: In most cases, the residual ginsenoside level decreased by 5.9-36.8% compared with the initial ginsenoside level. Ginsenosides Rb1, Rb2, Rc, and Re continuously decreased during fermentation. By contrast, Rd was maintained or slightly increased after 1 d of fermentation. Rg1 and Rg2 reached their lowest values after 1-2 d of fermentation, and then began to increase gradually. The conversion of Rd, Rg1, and Rg2 into smaller deglycosylated forms was more rapid than that of Rd from Rb1, Rb2, and Rc, as well as that of Rg1 and Rg2 from Re during the first 2 d of fermentation with LAB. Conclusion: Ginsenosides Rb1, Rb2, Rc, and Re continuously decreased, whereas ginsenosides Rd, Rg1, and Rg2 increased after 1-2 d of fermentation. This study may provide new insights into the metabolism of ginsenosides and can clarify the metabolic changes in ginsenosides biotransformed by LAB.

• Proceedings of the Korean Society for Applied Microbiology Conference
• /
• 1977.10a
• /
• pp.197.3-197
• /
• 1977

The microbial and chemical changes, and characterization of the predominant acid-producing bacteria in the swine manure ensilage blended with corn meal at a ratio of 50:50 were studied, The fermentation was dominated by Lactobacilli, which multiplied rapidly for the first 24 hrs. The acid production during the fermentation process caused rapid pH drop to 4.5, and controlled the population of E. coli and other organisms in the feedlot waste.(중략)

• Journal of Microbiology and Biotechnology
• /
• v.29 no.4
• /
• pp.558-561
• /
• 2019

This study aimed to understand the survival and growth patterns of bacteriophage-sensitive Weissella and Leuconostoc strains involved in kimchi fermentation. Dongchimi kimchi was prepared, and Weissella and Leuconostoc were co-cultivated in the dongchimi broth. Weissella cibaria KCTC 3807 growth was accompanied by rapid lysis with an increase in the bacteriophage quantity. Leuconostoc citreum KCCM 12030 followed the same pattern. The bacteriophage-insensitive strains W. cibaria KCTC 3499 and Leuconostoc mesenteroides KCCM 11325 survived longer under low pH as their growth was not accompanied by bacteriophages. The bacteriophage lysate of W. cibaria KCTC 3807 accelerated and promoted the growth of Leuconostoc. Overall, our results show that bacteriophages might affect the viability and population dynamics of lactic acid bacteria during kimchi fermentation.

• Journal of Microbiology and Biotechnology
• /
• v.34 no.6
• /
• pp.1197-1205
• /
• 2024

Filamentous fungi are important cell factories for the production of high-value enzymes and chemicals for the food, chemical, and pharmaceutical industries. Under submerged fermentation, filamentous fungi exhibit diverse fungal morphologies that are influenced by environmental factors, which in turn affect the rheological properties and mass transfer of the fermentation system, and ultimately the synthesis of products. In this review, we first summarize the mechanisms of mycelial morphogenesis and then provide an overview of current developments in methods and strategies for morphological regulation, including physicochemical and metabolic engineering approaches. We also anticipate that rapid developments in synthetic biology and genetic manipulation tools will accelerate morphological engineering in the future.