• Biotechnology and Bioprocess Engineering:BBE
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• v.1 no.1
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• pp.22-25
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• 1996

An Exponetial feeding strategy has been frequently used in fed-batch fermentation of recombinant E. coli. In this feeding scheme, growth yield and initial cell concentration, which can be erroneously determined, are needed to calculate the feed rate for controlling specific growth rate at the set point. The effect of the incorrect growth yield and initial cell concentration on the control of the specific growth rate was theoretically analyzed. Insignificance of the correctness of those parameters for the control of the specific growth rate was shown theoretically and experimentally.

• The Korean Journal of Food And Nutrition
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• v.29 no.6
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• pp.962-970
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• 2016

Commercialized production of onion vinegar, which has biological activities formed through alcohol and acetic acid fermentation, requires standardization. The objective of this study was to determine optimal conditions of sugar contents ($11{\sim}15^{\circ}Brix$) and agitation rate (100~300 rpm) of fermenter in the alcohol-acetic fermentation for producing onion vinegar. The alcohol and total acidity contents increased, whereas contents of total sugars decreased during alcohol fermentation. Contents of alcohol of 13 and $15^{\circ}Brix$ reactants were about 8% in 36 hr and total acidities of all samples were below 0.2% in 60 hr. During acetic fermentation, total acidity increased with highest value at 9 days (3.2% in 100 rpm), 10 days (4.1% in 200 rpm) and 8 days (4.3% in 300 rpm), respectively. From these results, sugar contents ($13^{\circ}Brix$) were measured for alcohol fermentation and agitation rate (300 rpm) for fast fermentation method of vinegar. The contents of total phenols, flavonoids and quercetin in onion vinegar were 33.3 mg/100 g, 3.0 mg/100 g and 2.0 mg/100 g, respectively. Onion vinegar showed an antimicrobial activity against Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium, Escherichia coli and Enterobacter aerogenes. Antioxidant effect of onion vinegar was 26.23% in DPPH radical inhibition and 58.58% in superoxide dismutase like activity, respectively. Fibrinolytic activity was 1.51 plasmin unit/mL in onion vinegar. In conclusion, onion vinegar processed by alcohol and acetic fermentation had nutritional values and potential biological activities.

• Korean Journal of Food Science and Technology
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• v.22 no.5
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• pp.533-538
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• 1990

In polysaccharide fermentation with Aureobasidium pullulans, the aeration effects on the production of polysaccharide and the rheological properties of fermentation broth were studied. The increase of the aeration rates from 0.5 to 2.0vvm at 500 rpm yielded the maximum specific production rate of polysaccharide from 0.046 to $0.093 (hr^{-1})$, and the maximum specific growth rate of cells from 0.168 to $0.192 (hr^{-1})$. The viscosity behavior of fermentation broths at the different aeration rates followed the power-law ${\tau}= K({\gamma})^n$. The viscosity attributed by cells was about 10% of the total viscosity of fermentation broth and most of viscosity was attributed by the polysaccharide produced. The relationship between power-law parameters and the concentration of polysaccharide generally satisfied the etㄴrations with the regression coefficient greater than 0.980, $lnK(t)= ln({\tau})_o-n(t)\;ln({\gamma})_o\;and\;K(t)=A P(t)^B$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.3
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• pp.426-431
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• 2001

We made the Toha-jeot added cabbage kimchi with Toha-jeot, which is salt-fermented Toha shrimp in Korean traditional fermented food. The physicochemical characteristics of cabbage kimchi for 5 week fermentation at 4$^{\circ}C$ were observed. The salt content was 2.10~1.50% during the fermentation period. The salt content decreased rapidly during the first week, stayed the same level until the 4 week and then decreased after the 4 week. The pH of control kimchi and Toha-jeot added cabbage kimchi were 5.69, 5,64, respectively on preparation day. The rate of decrease of pH of Toha-jeot added cabbage kimchi was slow as the fermentation processed. The total acidity of the two kinds of kimchi was increased. The total acidity was higher from Toha-jeot added cabbage kimchi than control cabbage kimchi at the later stage of fermentation. The contents of total sugar and reducing sugar were higher from Toha-jeot added cabbage kimchi than control cabbage kimchi at the early stage of fermentation. The total sugar and reducing sugar contents of the two kinds of cabbage kimchi were decreased gradually as the fermentation processed. The ascorbic acid contents of the two kinds of kimchi were decreased slightly at the early stage of fermentation and then increased from 2 to 4 week, while there was no further change at 5 week.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.5
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• pp.340-344
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• 2000

Microbial oxidation of D-sorbitol to L-sorbose by Acetobacter suboxydans is of commercial importance since it is the only biochemical process in vitamin C synthesis. The main bottleneck in the batch oxidation of sorbitol to sorbose is that the process is severely inhibited by sorbitol. Suitable fed-batch fermentation designs can eliminate the inherent substrate inhibition and improve sorbose productivity. Fed-batch sorbose fermentations were conducted by using two nutrient feeding strategies. For fed-batch fermentation with pulse feeding, highly concentrated sorbitor (600g/L) along with other nutrients were fed intermittently in four pulses of 0.5 liter in response to the increased DO signal. The fed-batch fermentation was over in 24h with a sorbose productivity of 13.40g/L/h and a final sorbose concentration of 320.48g/L. On the other hand, in fed-batch fermentation with multiple feeds, two pulse feeds of 0.5 liter nutrient medium containing 600g/L sorbitol was followed by the addition of 1.5 liter nutrient medium containing 600g/L sorbitol at a constant feed rate of 0.36L/h till the full working capacity of the reactor. The fermentation was completed in 24h with an enhanced sorbose productivity of 15.09g/L/h and a sorbose concentration of 332.60g/L. The sorbose concentration and productivity obtained by multiple feeding of nutrients was found to be higher than that obtained by pulse feeding and was therefore a better strategy for fed-batch sorbose fermentation.

• Microbiology and Biotechnology Letters
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• v.19 no.4
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• pp.398-404
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• 1991

- Ethanol production by calcium alginate-immobilized baker's yeast was studied in the continuous shaked-flask reactor (CSFR) using glucose medium as a feed. Immobilized cells were stable at 30~$37^{\circ}C$ and pH 4~8. Fermentation characteristics of immobilized baker's yeast were examined changing the initial glucose concentration employed were 50, 100 and 150 g/l, respectively. It was investigated that the influent glucose concentration and the dilution rate have an influence on the ethanol fermentation characteristics at steady state in continuous culture of immobilized baker's yeast. The optimum conditions for high ethanol productivity and low residual glucose output in ethanol prodution were shown to be 0.2 h ' for the dilution rate and 150 g/l for the influent glucose concentration. The maximum ethanol productivity, ethanol yield, specific growth rate and glucose conversion rate were around 7.12 g/$l\cdot h$, 0.23, 0.366 g/$l\cdot h$ and 78.43, respectively.

• The Korean Journal of Community Living Science
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• v.17 no.3
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• pp.123-131
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• 2006

To compare the quality characteristics, chunggugjang was prepared with Bacillus subtilis NRLSI IV on the different inoculum levels$(10^2,\;10^4,\;10^6,\;and\;10^8 CFU/ml)$ and fermentation times(0, 12, 24, 36, and 48 hours). Although significant change in total nitrogen content was not found, the content of amino type, soluble and ammonia type nitrogen was generally increased according to the increase in fermentation time. Decomposition rate of nitrogen was also increased by fermentation time and nitrogen solubility was the highest value(62-75.9%) at 48 hour fermentation. In results of color changes, it was found that L and a value were decreased but there was no significant changes in b value as fermentation time was increased. In chunggugjang made with long fermentation time, hardness was decreased and relative viscosity of viscous substance was gradually decreased after little increase at initial fermentation time. The effect of inoculum level on hardness and relative viscosity were similar to that of fermentation time, i.e. the decrease of these at high inoculum level. In activity of V-GTP, 36 hour incubation could produce the highest value whereas no effect of inoculum level was found during fermentation except at 48 hour. In chunggugjang made with $10^2CFU/mL$ of Bacillus subtilis NRLSI IV, the content of glucose, sucrose, raffinose and stachyose was dramatically decreased at initial fermentation time and that of phytic acid, oxalic acid, citric acid, tartaric acid and malic acid was also decreased during fermentation, although the increase in acetic acid was found.

• Journal of the East Asian Society of Dietary Life
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• v.21 no.6
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• pp.897-904
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• 2011

For set up the processing method of Byeo-Nuruk, we investigated the quality characteristics of Byeo-Nuruk according to the mixture ratio of rice and wheat, as well as the addition rate of moisture. After 12 hours of incubation, the temperature of Nuruk increased dramatically and reached a maxium temperature at 36 hours. After 36 hours, the temperature decreased gradually and was maintained at about $31{\sim}38^{\circ}C$. The ranges of pH and titratable acidity of Byeo-Nuruk were 4.85 to 7.42 and 1.0 to 2.3, respectively. A higher content of wheat ratio in Byeo-Nuruk, was associated with higher enzyme activities of ${\alpha}$-amylase, glucoamylase, and acidic-protease. Further, at a 70% wheat ratio, a 25% addition rate of moisture showed the highest enzyme activity. In the mixture ratio between rice and wheat, the 50:50 and 30:70 treatments contained the highest levels of microorganisms.

• Journal of Animal Science and Technology
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• v.59 no.6
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• pp.14.1-14.9
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• 2017

Background: Garlic and its constituents are reported to have been effective in reducing methane emission and also influence glucose metabolism in body; however, studies in ruminants using garlic leaves are scarce. Garlic leaves contain similar compounds as garlic bulbs, but are discarded in field after garlic bulb harvest. We speculate that feeding garlic leaves might show similar effect as garlic constituents in sheep and could be potential animal feed supplement. Thus, we examined the effect of freeze dried garlic leaves (FDGL) on rumen fermentation, methane emission, plasma glucose kinetics and nitrogen utilization in sheep. Methods: Six sheep were fed Control diet (mixed hay and concentrate (60:40)) or FDGL diet (Control diet supplemented with FDGL at 2.5 g/kg $BW^{0.75}$ of sheep) using a crossover design. Methane gas emission was measured using open-circuit respiratory chamber. Plasma glucose turnover rate was measured using isotope dilution technique of [$U-^{13}C$]glucose. Rumen fluid, feces and urine were collected to measure rumen fermentation characteristics and nitrogen utilization. Result: No significant difference in rumen fermentation parameters was noticed except for rumen ammonia tended to be higher (0.05 < P < 0.1) in FDGL diet. Methane emission per kg dry matter ingested and methane emission per kg dry matter digested were lower (P < 0.05) in FDGL diet. Plasma glucose concentration was similar between diets and plasma glucose turnover rate tended to be higher in FDGL diet (0.05 < P < 0.1). Nitrogen retention was higher (P < 0.05) and microbial nitrogen supply tended to be higher (0.05 < P < 0.1) in FDGL diet. Conclusion: FDGL diet did not impair rumen fermentation, improved nitrogen retention; while absence of significant results in reduction of methane emission, glucose turnover rate and microbial nitrogen supply, further studies at higher dose would be necessary to conclude the merit of FDGL as supplement in ruminant feedstuff.

• Microbiology and Biotechnology Letters
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• v.28 no.5
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• pp.298-302
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• 2000

Fermentation parameters were estimated by use of a vent gas analyzer coupled to a computer data acquisition system in cultivation of Phellinus linteus WI-001, pro-ducer of polysaccharides known to have potent anticancer activities. Oxygen uptake rate(OUR), a critical indicator of the cells activities, was calculated by applying oxygen mass balance. In addition, by dividing the oxygen uptake rate hy the total oxygen consumed, on-line estimation of the cells specific growth rate was successfully done. It was also possible to estimate cell concentration directly bt use of oxygen-cell yield($Y_{x/o}$ ) which was obtained based on a correlation between cell growth and total oxygen consumed.