• Preventive Nutrition and Food Science
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• v.1 no.1
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• pp.41-45
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• 1996

This study was conducted to develop the fermentation kinetic model for the prediction of acidity and pH changes in Kimchi as a function of fermentation temperatures. The fitness of the model was evaluated using traditional two-step method and an alternative non-linear regression method. The changes in acidity and pH during fermentation followed the pattern of the first order reaction of a two-step method. As the fermentation temperature increased from 4$^{\circ}C$ to 28, the reaction rates of acidity and pH were increased 8.4 and 7.6 times, respectively. The activation energies of acidity and pH were 16.125 and 16.003kcal/mole. The average activation energies of acidity and pH using a non-linear method were 16.006 by the first order and 15.813 kcal/mole by the zero order, respectively. The non-linear procedure had better fitting 개 experimental data of the acidity and pH than two-step method. The shelf-lives based on the time to reach the 1.0% of acidity were 33.1day at 4$^{\circ}C$ and 2.8 day 28$^{\circ}C$.

• Korean journal of food and cookery science
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• v.11 no.1
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• pp.37-43
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• 1995

Effect of the pretreatment with acetic acid(0.01%, 0.05%, 0.1%) on the fermentation of Chinese cabbage Kimchi, and differences in the degree of maturity between Chinese cabbage blades and midribs were observed. To estimate the degree of maturity, correlation analysis was used with several variables such as pH, titratable acidity, volatile acidity, ascorbic acid content, resazurin test value and pH/acidity ratio. Based on the pH and titratable acidity, the degree of maturity of Chinese cabbage midribs fermented at 10$^{\circ}C$ until the optimum stage of fermentation increased more rapidly than those of the blades. The stage of maturity of Kimchi pretreated with 0.01% acetic acid were slightly prolonged, compared to those pretreated with acetic acid at the higher levels. The pH of Chinese cabbage midribs and blades pretreated with acetic acid was lower than those of control between 2nd and l0th day of fermentation. The volatile acidity of Chinese cabbage midribs and blades increased proportionally with the concentration of acetic acid. The ascorbic acid contents of Chinese cabbage midribs showed higher than those of Chinese cabbage blades. During the fermentation, the higher concentration of acetic acid was used, the less ascorbic acid content was remained. The pH/acidity ratio, volatile acidity, ascorbic acid content and resazurin test value of Chinese cabbage midribs and blades during Kimchi fermentation at 10$^{\circ}C$ showed good correlations with the pH and titratable acidity.

• Archives of Pharmacal Research
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• v.17 no.4
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• pp.231-235
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• 1994

Fluorenecarboxaldehyde hydrazone 9FCH)was synthesized as a new fluorescent reagent for the determination of acidity. FCH had no fluorescence in itself, however, it strongly fluoresced under acidic conditions at excitation maximum of 392 nm and emission maximum of 447 nm, respectively. It showed good correlation with pH in the range from pH 0.60 to pH 3.60 in strong acids. As an application, the acidity of gastric juice in rats and humans was determined. In comparision with pH-metry, the acidity measured by the developed method showed generally increased values of about 0.7-1.3 unit and 0.8-1.2 unit in rats and humans, respectively. However, these results had statistically close correlation with those of pH-metry and the correlation coefficients were 0.887 in rats and humans between two methods.

• Restorative Dentistry and Endodontics
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• v.16 no.2
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• pp.189-196
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• 1991

The purpose of this study was to observe the inital acidity of zinc phosphate cements(Confit and Super Cem), poly carboxylate cement(Unident and Poly F), zinc oxide engenol cement(Stailine Super EBA) and g1ass ionomer cement(Fuji ionomer) Each cement was manuplated in accordance with each manufacturer's direction. All cements were mixed at the room temperature of $23^{\circ}{\pm}$, $5^{\circ}C$, and the electrode of pH meter(Ionanalyzer) was inserted in the mixed cement, and the acidity of cement were measured for 20 minutes from begining of cement mixing at $23^{\circ}C$ and $37^{\circ}C$ Results were as follows 1. The acidity of all cements ranges from pH 3, 5 to 4, 5 at 2 minutes after the start of mixing 2. The value of pH at $23^{\circ}C$ was higher than the value of pH at $37^{\circ}C$ in all cements. 3. As the time elapsed, the pH in all cements rose. The 20 minutes after the start of mixing the range of acidity was from pH 5 to pH 6 except Poly F. 4. In polycarboxylate cement, the different value of acidity at $23^{\circ}C$ and $37^{\circ}C$ was greatest. 5. The curve pattern of acidity in Unident was similar to that in Poly F cement The pH value of Unident was higher then that of Poly F, and value of pH in the curve pattern of acidity in Confit were similar to those in Super cement.

• Korean Journal of Agricultural and Forest Meteorology
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• v.6 no.3
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• pp.190-195
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• 2004

This study investigated effects of water content in leaf, leaf acidity, bark acidity and water soluble sulfur contents by vehicle. The results were as follows: The average water content in Pinus Koraiensis leaves at Cheongpyoung and Chuncheon were 49% and 51 % respectively. The average leaf acidity and bark acidity at Cheongpyoung and Chuncheon were respectively pH 4.8 and pH 4.9 in leaf, pH 5.3 and 5.4 bark. The average water soluble sulfur content in leaves showed a significant difference between Cheongpyoung and Chuncheon of 0.133% and 0.053% respectively.

• Journal of Environmental Science International
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• v.1 no.1
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• pp.29-39
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• 1992

A study on acidity in precipitation was carried out during May 1990 - April 1991 at two sites in Chongwon, Choongbook. We observed variations of pH from 4.0 to 7.0. Annual mean value of pH was 5.21 in the area. In particular, strong acidity of rain fall, pH 4.0 were observed during winter to early spring. Neutral values were observed during June to July and were due to wet deposition of atmospheric pollutants by stationary fronts in the rainy season. Interestingly, acidity of snow observed in winter was neutral and it was weaker than the acidity of rain in winter by a value of 2.0. Discussion is made on meteorological and chemical analyses and seasonal variations of acidity of precipitation.

• Korean Journal of Agricultural Science
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• v.24 no.2
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• pp.156-169
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• 1997

This experiment was carried out to exame the effects of sweeteners, sucrose(2.0~10.0%), aspartame(0.01~0.05%) and oligosaccharide(3.6~11.6%) on the fermentation of yoghurts by single or mixed culture (Lact. bulgaricus and Str. thermophilus). The acidity, pH and number of lactic acid bacteria in yoghurts added different level of sweeteners were examined by the fermentation time. The results were summarized as follows; 1. The acidity increased and the pH decreased more rapidly by 4.0% sucrose and 5.6% oligosaccharide. By the addition of 8.0% sucrose and 9.6% oligosaccharide the acidity and pH of yoghurts were changed less significantly. 2. The number of Lact. bulgaricus and Str. thermophilus increased more rapidly by 4.0% sucrose and 5.6% oligosaccharide and increased slowly above those levels. 3. Aspartame as a sweeteners did not affect on the acidity, pH and number of lactic acid bacteria in yoghurts. 4. The number of lactic acid bacteria, acidity and pH in yoghurts added sucrose and oligosaccharide were affected more by single culture than by mixed culture.

• Food Science and Preservation
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• v.11 no.1
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• pp.34-37
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• 2004

Calcium powder from whey (WCF) was added to enrich the calcium content of kimchi, and the mixing ratios of it to salted Chinese cabbage were 0.5, 1.0 and 1.5％. Quality characteristics of kimchi such as pH, titratable acidity, reducing sugar content and microbial loads were measured during fermentation at 10$^{\circ}C$. Kimchi samples with WCF showed a higher level in pH and titratable acidity than that of control during fermentation. Kimchi having higher WCF maintained a higher in pH and titratable acidity, and titratable acidity was above 1.0％ about 12 days in kimchi sample with 0.5％ WCF. Reducing sugar content was steadily decrease after 5 days, and control maintained a higher than others. Microbial load was similar until 10 days, but control was lower than kimchi samples with WCF. Based on the titratable acidity, kimchi with WCF had a limitation in shelf life.

• Journal of the East Asian Society of Dietary Life
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• v.7 no.1
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• pp.57-63
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• 1997

In order to use leaf mustard Dolsan food preservative ingradient acidity, antimicrobial activity and colors were investigated during pretreatment of leaf mustard Dolsan. pH was remarkably decreased after 8 hours to pretreatment(extracted on shaking) of leaf mustard Dolsan, and no changes were observed after that time. pH of leaf part was higher than stalk after 8 hours storage. Titratable acidity was opposite tendency to the pH. pH was gradually decreased than initial stage during pretreatment of leaf mustard Dolsan at 30, 40 and 5$0^{\circ}C$. After 16 hours pretreatment, the higher pretreatment temperature was, the higher pH was, but after pretreatment for 48 hours, pH of sample pretreated at 5$0^{\circ}C$ was lower than that of sample pretreated at 40 $^{\circ}C$. Antimicrobial activity of leaf mustard Dolsan extract pretreated at 3$0^{\circ}C$ was the strongest of the samples pretreated at 30, 40 and 5$0^{\circ}C$, and that of stalk part was stronger than that of leaf part. L and time. L and b value was higher in the order of samples pretreated at 40, 50 and 3$0^{\circ}C$, and the lower pretreatment temperature was, the higher a value was. L value of stalk part was higher than that of leaf part, but a and b value of leaf part was higher than that of stalk part.

• Korean Journal of Food Science and Technology
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• v.35 no.2
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• pp.316-319
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• 2003

Titratable acidity, pH, color, and pungency characteristics of commercial kimchi were investigated. Titratable acidity and of pH commercial kimchi waried significantly from pH 3.88 and titratable acidity 0.28% in non-fermented kimchi, to pH 6.20 and titratable acidity 1.13% in over-fermented one. Capsaicinoid contents of kimchi showed low pungency intensity of 0.18% to strong pungency intensity of 2.02, and American spice trading association value of kimchi samples ranged $0.52{\sim}4.1$.