• Journal of Korean Society of Environmental Engineers
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• v.27 no.2
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• pp.184-190
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• 2005

A new VFAs production process from sewage sludge using Fenton's oxidation was investigated. Optimum concentrations of $H_2O_\;and\;Fe^{2+}$ as well as optimum reaction temperature for VFAs production were studied. In the presence of $Fe^{2+}$ as catalyst, the VFAs formation rate increased about 4 times compared to $H_2O_2$ oxidation process without $Fe^{2+}$. Optimum concentrations of $H_2O_2$ and $Fe^{2+}$ were 0.62 M and 0.007 M, respectively. VFAs formation reaction proceeded rapidly within 1 min and VFAs formed degraded partly to acetic acid and $CO_2$, which exhibited series reaction characteristics. Based on the economic aspect, reaction temperature of $25^{\circ}C$ and 10 min of reaction time were thought to be proper reaction conditions. The effect of initial pH in the range of $3{\sim}6.3$ on the VFAs formation was not observed.

• Korean Journal of Food Science and Technology
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• v.30 no.3
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• pp.548-551
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• 1998

Physicochemical characteristics of the Korean type hot sauce during storage were investigated. Chemical analysis of the Korean type hot sauce showed as follows; pH 3.29, titratable acidity 3.88%, capsanthin 0.13% and capsaicin 2.68 mg%. The contents of capsanthin and capsaicin except pH and titratable acidity decreased during storage for 50 days at 20 and $30^{\circ}C$. The results of sensory evaluation showed the decrease of value according to storage time. Especially change of color in sensory evaluation was outstanding. For correlationship between the color of sensory evaluation and capsanthin content was high, capsanthin content was selected as a quality index of the Korean type hot sauce. Shelf-lives of the Korean type hot sauce were predicted to be 232.5 days at $20^{\circ}C$, and 178.0 days at $30^{\circ}C$, respectively.

• Food Science and Preservation
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• v.10 no.3
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• pp.288-292
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• 2003

Grapefruit seed extract powder (GFSEP), which was made with grapefruit seed extract and calcium carbonate, was investigated to retard the fermentation rate. The mixing ratios of GFSEP to salted Chinese cabbage were 0.1, 0.3 and 0.5％. Quality characteristics of kimchi such as pH, titratable acidity, reducing sugar content and microbial loads were measured during fermentation at 10$^{\circ}C$. pH and reducing sugar content of control and kimchi sample with 0.1％ GFSEP showed decreases until 10 days, and then attained to stabilized levels. Kimchi samples with 0.3％ and 0.5％ GFSEP maintained a higher pH and reducing sugar content, while microbial load was lower than others. Based on the pH and tit ratable acidity, kimchi samples with GFSEP prolong the shelf life about 3～10 days.

• Journal of the Korean Home Economics Association
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• v.42 no.3
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• pp.145-158
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• 2004

Experimental conditions for evaluating chitosan antibacterial activities were established. The chitosan antibacterial activities were measured against the Staphylococcus aureus and evaluated for their application to antibacterial textile finishing. The strain of Staphylococcus aureus used in this experiments was KCTC 1916. The chitosan antibacterial activities were estimated from the bacterial densities or ％reduction of bacteria in chitosan solutions and bacterial culture mixtures after incubation under specific conditions. Six parameters as follows were evaluated to optimize the experimental conditions for measuring antibacterial activities. The different combinations of mixtures according to the different ratios of chitosan solutions to the bacterial cultures showed different antibacterial activities. However, the chitosan antibacterial activities could be evaluated by comparing the data obtained from the same combinations of mixtures. The solvent influence on the chitosan solution antibacterial activities could be eliminated using control solution containing the same concentration of acetic acid. The initial pH of the chitosan -bacterial mixtures also affected the chitosan antibacterial activity; at a higher pH, higher activity in terms of ％reduction of bacteria was observed. In case of the bacterial solution without either the acetic acid or chitosan, the initial pH of the solution did not significantly affect bacterial growth. The ％ reduction of bacteria increased when contact times of bacteria with chitosan in the chitosan -bacterial mixture were expended upto 24 hours. However, the chitosan antibacterial activities could be successfully evaluated at contact time 0 where the chitosan-bacterial mixture was plated immediately after mixing and incubated to measure the bacterial number to 24 hours. Evaluating ％reduction of bacteria in the test mixtures after incubation were not changed when the inoculated bacterial concentrations were 2.3${\times}$10$\^$0/ml to 2.3${\times}$10$\^$6/ml. The optimal range of incubation time of the petri-Dish after plating the chitosan-bacterial mixture was 24 to 72 hours depending on the antibacterial activities of the test solutions.

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.1018-1022
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• 2002

Effect of nitric oxide (NO) treatment on physiology and quality characteristics of peaches (Prunus persica L. Batsch) was determined. Peaches were treated for 4 hr with NO (0, 10, 100 ppm) gas under oxygen-free atmosphere at $10^{\circ}C$, packaged with 0.05-mm LDPE film, and stored at $10^{\circ}C$ for 15 days. Treatment with 100 ppm NO reduced the ethylene production and the loss of flesh firmness in peaches, but did not affect soluble solids, titratable acidity, and surface color. Oxygen-free atmosphere induced the reduction of respiration rate and ethylene production. Modified atmosphere packaging retarded the loss of flesh firmness and surface greenness, but decreased soluble solids and titratable acidity regardless of NO treatment.

• Food Engineering Progress
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• v.14 no.1
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• pp.27-34
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• 2010

Multilayer edible coatings was applied to lemon with beeswax-hydroxypropyl methylcellulose (BW-HPMC), soybean oil-carboxymethyl cellulose (SBO-CMC), and carnaubawax-shellac-locust bean gum (CW-SL-LBG), respectively. The multilayer was composed of two layers of the same material, but the outer layer only contained vitamins C and E as antioxidants. Coating amounts built on lemon peel were measured to be large in the order of CW-SLLBG> BW-HPMC> SBO-CMC. The coated lemons were stored at 30${^{\circ}C}$ for 12 days. CW-SL-LBG showed the least change during the storage in weight loss, rotten rate, firmness, and browning. Whereas SBO-CMC had the least change in pH, soluble solid amount, and titratable acidity. In a sensory test, CW-SL-LBG was evaluated to be the best in the attributes such as spoilage, glossiness, color, firmness, and flavor. Overall CW-SL-LBG was judged to be the best for multilayerd coating with vitamin C and E on lemon.

• Journal of The Korean Association For Science Education
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• v.28 no.1
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• pp.67-74
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• 2008

The purpose of this study was to investigate the effects of an MBL instrument in laboratory execution by analyzing an experimental time and student to student interactions in the MBL and traditional method of the acid-base titration experiment. The MBL method used a conductivity sensor and the traditional method used a current meter on the HCl/NaOH titrations. In comparison of the two methods, the traditional method required more time than the MBL and most of the extra time were used in the execution. In the execution, the MBL method showed more numbers of student to student interaction and higher level of verbal interaction than the traditional method.

• Korean Journal of Agricultural Science
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• v.26 no.1
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• pp.39-49
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• 1999

Curd yoghurts were manufactured by addition of chestnuts and walnuts which were special agricultural products in Chungnam area. The nut powders were added to the yoghurts in the given concentration of 1~4%. The yoghurts after 12 hours fermentation were examined for pH, acidity, cell counts of lactic acid bacteria, viscosity, chemical composition and sensory test and preservation of yoghurts. The results obtained were summarized as follows; 1. The chestnut powder decreased pH, whereas increased acidity in yoghurts, however, the walnut powder did not change significantly for pH and acidity in yoghurts. 2. The cell counts of lactic acid bacteria was higher for 2% chestnut powder yoghurt ($2.6{\times}10^9/ml$) than 2% walnut powder yoghurt ($1.7{\times}10^9/ml$) and control yoghurt. 3. The viscosity of yoghurt was higher for 4% chestnut powder yoghurt (3,225 centipoise) than control (1,638 centipoise) and 4% walnut powder yoghurt (2,010 centipoise). 4. The protein content of yoghurts were 3.99% for both 2% chestnut powder and 2% walnut powder yoghurts, and solid-non-fat contents of yoghurt were 15.10% for chestnut powder yoghurt and 13.65% walnut powder yoghurt. 5. The scores of sensory tests were higher in chestnut powder yoghurt for tastes, odor and texture, and in walnut powder yoghurt for tastes, odor and texture compared to control yoghurt. 6. When yoghurts were stored at $5^{\circ}C$ for 14 days for preservation test, the acidity and number of lactic acid bacteria were not changed significantly.

• Korean Journal of Food Science and Technology
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• v.29 no.1
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• pp.115-119
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• 1997

The chemical and microbial properties and acceptability of milk and soymilk inoculated with Bifidobacterium were studied at each storage time (0, 5, 10, 15, 20, 25, and 30 days). Soymilk, milk, low-heat milk, low-fat milk, non-fat dry milk with Bifidobacterium longum ATCC 15707 were incubated in a nitrogen-carbon dioxide atmosphere at $4^{\circ}C$ for 30 days. pH and acidity of all the samples were in the range of $pH\;6.6{\sim}pH\;6.9$ and $0.4%{\sim}0.55%$ for 30 days, respectively. The viable cell numbers in non-fat dry milk reached above $8.4{\times}10^9\;CFU/mL$ after 15 days. The glucose content in soymilk was $4.5{\times}10^{-2}{\sim}5.5{\times}10^{-2}\;mM$ at 10 days of storage. Milk and soymilk containing B. longum at $4^{\circ}C$ were found to be different in taste, odor, off-flavor at each storage time (0, 2, 4, 6, 8, and 10 days). Sensory scores indicated that milk containing bifidobacteria was poorly affected by the storage time, but milk at 4 days of storage was quite close in odor and off-flavor to milk with storage time 0. Soymilk containing bifidobacteria at 2 and 4 days of storage had significantly higher acceptability of taste than soymilk with storage time 0.

• Food Science and Preservation
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• v.14 no.1
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• pp.94-99
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• 2007

To investigate the effects of Pichia anomala SKM-T and Galactomyces geotrichum SJM-59 on Baechu kimchi fermentation, lyophilized yeasts were added to Baechu kimchi and co-cultured at room temperature ($20{\pm}2^{\circ}C$) for 7 days. Desirable pH and acidity levels appeared by 3 days of fermentation in both the control culture and that with added G. geotrichum SJM-59. Furthermore, the culture with G. geotrichum SJM-59 sustained a desirable pH and acidity level until 5 days of co-culture. The pH of the culture with P. anomala SKM-T decreased slowly and was significantly higher than that of control throughout the experimental period. As fermentation time increased, the acidity of the culture with P. anomala SKM-T increased gradually. However, this culture maintained a desirable acidity level throughout the experiment. The number of lactic acid bacteria in the culture with P. anomala SKM-T was higher than in the culture with G. geotrichum SJM-59, or the control culture, throughout the experiment. The highest LA/TM ratio appeared after 3 nays of fermentation in the control culture, and on the 5 day of the yeasts added co-cultures. On sensory evaluation, no differences were detected between control and the culture with G. geotrichum SJM-59 arter 3 days of fermentation. The co-cultures with yeasts received high marks in umami taste. The co-culture with P. anomala SKM-T showed better texture properties than did the control culture. It was considered that fermentation times were delayed by addition of G. geotrichum SJM-59 or P. anomala SKM-T to Baechu kimchi fermentation.