• Korean Journal of Food Science and Technology
• /
• v.26 no.6
• /
• pp.726-732
• /
• 1994

Development of an effective method for the preparation of dongchimi juice was investigated by addition of NaCl, sucrose and hydrolytic enzymes before fermentation and addition of dongchimi juice during fermentation. The Chinese radish was ground and suspended in water (1:1, w/v) with addition of spices of garlic, green onion and ginger followed by fermentation at $25^{\circ}C$. Increase in NaCl concentration of brinning solution from 1.0 to 5.0% resulted in a significant decrease in the rates of pH decrease and acidity increase. The sugar addition resulted in a faster changes of them, particulary after 24 hours at $25^{\circ}C$. The fermentation rate was also greatly improved by enzymatic hydrolysis with using viscozyme, a commercial polysaccharides hydrolyzing enzyme, before fermentation. When the fermented juices of two stage (pH 5.4 and pH 4.4) were added up to 15% before (pH 5.4 juice) and during (pH 4.4 juice) fermentation, the initial and second stage of fermentation were significantly improved. Therefore a method of addition of sugar, hydrolytic enzymes and dongchimi juice before or during fermentation was suggested for dongchimi juice preparation.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.42 no.6
• /
• pp.569-573
• /
• 2009

The biochemical and microbiological changes of the hard clam shikhae were studied during fermentation at $4-18^{\circ}C$ for 45 days. For preparation of the shikhae, the shucked hard clams were blanched into 2% saline solution and were soaked in seasoning solution before mixing with salt, cooked grain and spices. During fermentation, the initial pH steadily decreased from 5.0 to 4.6, but $NH_2-N$ and VBN concentrations increased to 127 mg/100 g and 27.0 mg/100 g, respectively. Alanine, taurine, glutamic acid, and aspartic acid concentrations increased, but arginine concentration decreased by fermentation. The major organic acids of the fermented shikhae were lactic acid, succinic acid and acetic acid. The major free sugar were maltose, glucose and fructose. The concentration of total viable cell ($2.1\times10^5$ CFU/g) and proteolytic bacteria ($1.2\times10^5$ CFU/g) increased to $4.4\times10^8$ CFU/g and $9.8\times10^7$ CFU/g, respectively until day 15 and then slightly decreased. The concentration of yeast ($2.4\times10^3$ CFU/g) increased to $1.6\times10^7$ CFU/g until day 25, but lactic acid bacteria ($5.0\times10^8$ CFU/g) increased to $5.0\times10^8$ CFU/g until day 9. Vibrio species was not detected on the TCBS agar during fermentation.

• 한국생물공학회:학술대회논문집
• /
• 2005.10a
• /
• pp.272-276
• /
• 2005

Candida tropicalis, an osmophilic strain isolated from honeycomb, produced xylitol at a maximal volumetric production rate of 3.5 g $l^{-1}$ $h^{-1}$ from an initial xylose concentration of 200 g $l^{-1}$. Even with a very high xylose concentration, e.g., 350 g $l^{-1}$, this strain produced xylitol at a moderate rate of 2.07 g $l^{-1}$ $h^{-1}$. In a fed-batch fermentation of xylose and glucose, 260 g $l^{-1}$ of xylose was added, and xylitol production was 234 g $l^{-1}$ for 48 h, corresponding to a rate of 4.88 g $l^{-1}$ $h^{-1}$. To increase the xylitol production rate, cells were recycled in a submerged membrane bioreactor with suction pressure and air sparging. In cell-recycle fermentation, the average concentration of xylitol produced per recycle round, total fermentation time, volumetric production rate, and product yield for ten rounds were 180 g $l^{-1}$, 195 h, 8.5 g $l^{-1}$ $h^{-1}$, and 85%, respectively. When cell-recycle fermentation was started with the cell mass contratrated two-fold after batch fermentation and was performed for ten recycle rounds, we achieved a very high production rate of 12 g $l^{-1}$ $h^{-1}$. The production rate and total amount of xylitol produced in cell-recycle fermentation were 3.4 and 11 times higher than in batch fermentation, respectively.

• The Korean Journal of Food And Nutrition
• /
• v.22 no.3
• /
• pp.377-386
• /
• 2009

The principal objective of this study was to evaluate the influence of temperature and salt concentration on the physicochemical properties of salted Chinese cabbage. Salted Chinese cabbage samples were prepared with various concentrations of salt(4, 5, 6 and 7%), and were stored for 10 days at three temperatures(8, 14, and $25^{\circ}C$). The salting ratio of Chinese cabbage evidenced a decreasing trend regardless of the salting temperature and salt concentration, and their decrement appeared relatively high as the salting temperature increased. The period required to achieve a critical salting ratio(85%) decreased with increases in the salt concentration at $25^{\circ}C$, and a similar trend was observed at lower temperatures(8 and $14^{\circ}C$). The salinity of all samples evidenced an increasing trend during the salting period, and at $25^{\circ}C$, in particular, a continuous increment was observed. At salt concentrations of 4%, the critical salinity(2.2%) was not achieved regardless of the temperature and salting period. The pH of salted Chinese cabbage achieved critical pH in 3 days at a salting temperature of $25^{\circ}C$, but the critical pH 5.5 of samples at 8 and $14^{\circ}C$ appeared after a long period of approximately 4 to 10 days. The average hardness values of salted Chinese cabbage at a salting ratio of 85% were approximately 1.49 MPa, 1.87 MPa, and 1.97 MPa, respectively, at three temperatures($25^{\circ}C$, $14^{\circ}C$, and $8^{\circ}C$). The initial reducing sugar content of cabbage juice was 11.8 mg/$m{\ell}$, and this value decreased substantially to 3 to 5 mg/$m{\ell}$ on day 1.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.4
• /
• pp.511-517
• /
• 2013

In this work, a fibrous bed bioreactor with high specific surface area and good adsorption efficacy for S. cerevisiae cells was used as the immobilization matrix in the production of ethanol. In batch fermentation, an optimal ethanol concentration of 91.36 g/l and productivity of 4.57 g $l^{-1}\;h^{-1}$ were obtained at an initial sugar concentration of 200 g/l. The ethanol productivity achieved by the immobilized cells was 41.93% higher than that obtained from free cells. Ethanol production in a 22-cycle repeated batch fermentation demonstrated the enhanced stability of the immobilized yeast cells. Under continuous fermentation in packed-bed reactors, a maximum ethanol concentration of 108.14 g/l and a productivity of 14.71 g $l^{-1}\;h^{-1}$ were attained at $35^{\circ}C$, and a dilution rate of 0.136 $h^{-1}$ with 250 g/l glucose.

• The Korean Journal of Mycology
• /
• v.10 no.2
• /
• pp.75-83
• /
• 1982

As a primary study for cell growth and alcohol production of a cider yeast, Saccharomyces sp. R-11, cultural and nutritional characteristics of the strain were investigated. The results obtained were as follows: The optimum culture medium for this strain was a synthetic medium, Henneberg B, and sucrose was the best carbon source for yeast growth and alcohol production. Optimum sugar concentrations for yeast growth and alcohol production were 15% and 25%, respectively. Optimum pH and temperature of the basal medium for growth of this strain were 4.5 and $30^{\circ}C$ respectively. The yeast growth was enhanced by the addition of 100 ppm of $Mg^{2+}$, but significantly inhibited by the addition of 100 ppm of $Co^{2+}$. Lower temperature and maintenance of optimum pH for yeast growth increased the final alcohol concentration. Under optimum condition for cell growth at stationary culture, generation time and specific growth rate of the strain were 7.5 hr and 0.092 $hr^{-1}$, respectively. At 8% initial alcohol concentration, yeast growth was inhibited about 50% and this strain could not be grown at more than 12% initial alcohol. The strain could be grown at less than 125ppm $SO_2$without alcohol addition, and at less than 75 ppm $SO_2$ with 8% initial alcohol. The higher sulfur dioxide concentration of a medium, the longer lag phase in yeast growth was observed. This strain could induced alcoholic fermentation at less than 10% initial alcohol concentration with 0 and 25 ppm $SO_2$, at less than 8% initial alcohol with 50 and 75 ppm $SO_2$, and at less than 6% initial alcohol with 100 and 125 ppm $SO_2$.

• Journal of the Korean Wood Science and Technology
• /
• v.20 no.3
• /
• pp.11-20
• /
• 1992

Steam explosion is one of the most effective pretreatment for fractionating wood. This leads to the total utilization of wood basic components; cellulose, hemicellulose and lignin. The amount of sugar and lignin extracted with the hot water method was very low. The lignin content of residues after extraction with using a sodium hydroxide treatment, increased delignification of carbohydrate as the concentration of alkali was increased. Oak, pretreated with steam exploded at 25kg/$cm^2$ for 6 min. then 1% alkali for 2hrs. showed a delignification rate up to 95%. A sodium chlorite treatment of steam exploded pine and oak also afforded a high deligninfication effect. Pine, treated 10% sodium chlorite for 2hrs. showed high delignification. However, by using a sodium hydroxide treatment, a 2% retreatment for Ihr. after a 2% for 2hrs. afforded remarkable delignification effect on exploded wood at 30kg/$cm^2$ for 9min. and at 35kg/$cm^2$ for 3-6min. In oak, an initial 2hrs. treatment of 2% sodium chlorite was followed by a second 2hrs. treatment at 10%. This showed a delignification rate of 96%.

• Mycobiology
• /
• v.34 no.1
• /
• pp.22-29
• /
• 2006

Forty-one fungal species belonging to 15 fungal genera isolated from Egyptian soil and sugar cane waste samples were tested for their capacity of producing acidity and gluconic acid. For the tests, the fungi were grown on glucose substrate and culture filtrates were examined using paper chromatography analysis. Most of the tested fungi have a relative wide potentiality for total acid production in their filtrates. Nearly 51% of them showed their ability of producing gluconic acid. Aspergillus niger was distinguishable from other species by its capacity to produce substantial amounts of gluconic acid when it was cultivated on a selective medium. The optimized cultural conditions for gluconic acid yields were using submerged culture at $30^{\circ}C$ at initial pH 6.0 for 7 days of incubation. Among the various concentrations of substrate used, glucose (14%, w/v) was found to be the most suitable carbon source for maximal gluconic acid during fermentation. Maximum values of fungal biomass (10.02 g/l) and gluconic acid (58.46 g/l) were obtained when the fungus was grown with 1% peptone as sole nitrogen source. Influence of the concentration of some inorganic salts as well as the rate of aeration on the gluconic acid and biomass production is also described.

• Food Science and Biotechnology
• /
• v.18 no.6
• /
• pp.1342-1350
• /
• 2009

This paper investigates the production and optimization of $\beta$-galactosidase enzyme using synthetic medium by Kluyveromyces lactis NRRL Y-8279 in stirred tank bioreactor. Response surface methodology was used to investigate the effects of fermentation parameters on $\beta$-galactosidase enzyme production. Maximum specific enzyme activity of 4,622.7 U/g was obtained at the optimum levels of process variables (aeration rate 2.21 vvm, agitation speed 173.4 rpm, initial sugar concentration 33.8 g/L, incubation time 24.0 hr). The optimum temperature and pH of the $\beta$-galactosidase enzyme produced under optimized conditions were $37^{\circ}C$ and pH 7.0, respectively. The enzyme was stable over a pH range of 6.0-7.5 and a temperature range of $25-37^{\circ}C$. The $K_m$ and $V_{max}$ values for O-nitrophenol-$\beta$-D-galactopyranoside (ONPG) were 1.20 mM and $1,000\;{\mu}mol/min{\cdot}mg$ protein, respectively. The response surface methodology was found to be useful in optimizing and determining the interactions among process variables in $\beta$-galactosidase enzyme production. Hence, this study fulfills the lack of using mathematical and statistical techniques in optimizing the $\beta$-galactosidase enzyme production in stirred tank bioreactor.

• Journal of the East Asian Society of Dietary Life
• /
• v.10 no.5
• /
• pp.425-430
• /
• 2000

Physicochemical properties of Kochujang(OK) added onion powder (OK ) were Investigated duringstorage at 20"C The pH value of Kochujang tended to decrease by condition of storage. Initial pH value of OK was significantly lower than that of control, but the difference of pH value was getting smaller during the storage period. In the Process of 90 days storage period, the pH value of OK containing 8 and 10% of onion powder was higher than control. Salt content was lower in OK than in control as the onion content was higher No changes in salt content were observed during the storage process. Reducing sugar was higher in OK than in control, and Its concentration was increased with onion content. Amino acid nitrogen content which was slightly higher in OK than in control increased during 45 days of storage period and tended to decrease afterward. In the sensory attribute data of Kochujang after 3 months of storage period, OK had higher scores in sweetness, color, flavor, and overall acceptability than control, especially the OK with 10% onion powder had the highest scores.scores.