• Food Science and Preservation
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• v.15 no.3
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• pp.483-490
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• 2008

Several tartaric acid-degrading bacteria were isolated from Korean grape wine pomace after enrichment culture at $30^{\circ}C$ for 10 days in liquid media containing tartaric acid Among them, strains KMBL 5777 and KMBL 5778 exhibited the highest level in the growth and tartaric acid degradability in a medium containing 0.2%(w/v) tartaric acid as a sole carbon source. They were identified as Acetobacter tropicalis based on their morphological and physiological characteristics as well as their 16S rDNA sequences. Blast search of the 16S rDNA sequences revealed that the isolated strains are closest to Acetobacter tropicalis. Homologies of the sequences of KMBL 5777 and KMBL 5778 were 96.0 and 98.9%, respectively with those of A. tropicalis LMG 1663. Both the two bacteria showed higher tartaric acid degradation at $25^{\circ}C$ that those at 20 and $30^{\circ}C$. They could degrade tartaric acid at a wide range of pH between 4.0 and 7.0 with the most rapid degradability at pH 7.0. However, when the bacteria were grown for 8 days, the same level of tartaric acid degradation was observed at pH 4.0, 5.0, 6.0 and 7.0, which was 90.0% of degradation of the acid.

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.680-685
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• 1998

Two kinds of new aliphatic diols were synthesized by the ring-opening reaction of lactide and glycolide with 1,4-butanediol, a difunctional initiator, in the presence of stannous octoate. The resulting aliphatic diols were melt-polymerized with D-tartaric acid at 150 ℃ to produce new crosslinkable polyesters. They were reacted with hexamethylene diisocyanate in THF at 65 ℃ in a teflon mold for 24 h to prepare sequentially ordered crosslinked polyesters (BD/LT/GL/D-tartarate). Degradation of the prepared yellow crosslinked films was carried out in a buffer solution in order to examine the effect of time, pH, temperature and crosslinking degree on their degradation rate and mechanism. The rate of degradation increased with an increase in pH and temperature, but it decreased with increasing degree of crosslinkage incorporated into the crosslinked polyesters. We also found that the crosslinked polymers were converted into the acidic compounds such as lactic, glycolic, and D-tartaric acids during the degradation.

• Korean Journal of Food Science and Technology
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• v.28 no.2
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• pp.352-359
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• 1996

Stabilities of purple sweet potato (PSP) anthocyanin pigment on pH, sugars, organic acids, metal ions, ascorbic acid and light were investigated to provide the basic information for utilization of PSP as a potential source of anthocyanin pigment. pH has a marked influences on the color of the PSP anthocyanin solution; i.e., at low pH the color of PSP was more intense and stable. It showed characteristic bathochromic shift as the pH of the solution increased. Among the sugars tested, glucose showed a protective effect on the color of PSP pigment to raise the color intensity and stability, while sucrose and fructose showed an adverse effect. Addition of organic acids greatly increased the stability of PSP anthocyanin pigment. Citric acid was found to be the most effective followed by malic. tartaric, and succinic acids. Most metal ions except $Al^{3+}$ and $Cd^{2+} were found to be detrimental effect on the stability of PSP pigment. Ascorbic acid degraded PSP pigment considerably, and had a synergistic effect with oxygen on the pigment degradation. The effect of light on PSP pigment was found to be very deleterious. The pigment degradation can be minimized by shielding the light from the pigment solution.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.9
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• pp.1544-1551
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• 2004

Effects of pH, sugar, ascorbic acid, organic acids and light sources on the stability of anthocyanin pigment extracted from Korean purple-fleshed potatoes (PL-6, PL-28, PL-31 and Jasim) were studied. The pH had remarkable influence on the color stability of anthocyanin pigment. With increasing pH, the color gradually fades as colorless pseudobases are formed. In acidic pH, anthocyanin was stable, but with increasing pH the color gradually changed to colorless. The addition of sugar decrease in color stability of the pigment during storage period. The most of organic acids, such as a tartaric, citric and succinic acids, were found to improve the stability of the pigment, while malic and malonic acid reduced the stability of the pigment. The addition of ascorbic acid considerable decreased in anthocyanin pigment stability, but the effect was not decreased by adding thiourea. The effect of light sources such as a darkroom, a fluorescent light, and sunlight, reduced gradually the stability of anthocyanin pigment. Therefore the pigment degradation could be minimized by shielding the light from the pigment.

• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.211-217
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• 1997

The physical and chemical stability of anthocyanins from a Korean pigmented rice variety was investigated at various conditions of pH, temperature, metal ion, sugar, organic acid and light. The anthocyanin pigments were relatively stable with half-lives of 36 days (pH 2.0) and 17 days (pH 3.0), while they were decomposed in a day at neutral and basic pH of 7.0 and 9.0 at $25^{\circ}C$. The anthocyanins also showed high thermal stability at pH 3.0; the half-lives were 7.4 hr, 23.6 hr and 96.3 hr at $95^{\circ}C,\;75^{\circ}C\;and\;50^{\circ}$, respectively. Addition of di- and tri-valent metal ions at pH 3.0 resulted in the increase of color intensity and stability throughout 21 days of storage periods at $25^{\circ}C$. Most sugars added accelerated the degradation of anthocyanin pigments, so that fructose showed the greatest degradation effect on the pigments. Addition of citric acid at pH 3.0 increased stability of anthocyanins, while tartaric acid decreased stability. The anthocyanins were very sensitive on light irradiation with a degradation half-life of 14 hr under 20,000 lux-light dosage at pH 3.0.

• Journal of the Korean Society of Food Science and Nutrition
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• v.11 no.3
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• pp.67-74
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• 1982

The effect of various pH levels, temperatures. organic acids, inorganic salts, metal ions on the stability of the anthocyanins pigment (pH 3.7) from the juice of raspberries were investigated. Initial absorption of total anthocyanin was decreased as pH increased from 1.0 to 7.0. Total amount of anthocyanin reached the highest at pH 3.7 and least at pH 7.0. The total anthocyanin content decreased rapidly with the increasing temperature. Many organic acids were found to enrich and stabilize the color density at 520nm in anthocyanin solution (pH 3.7). The hyperchromic effect of saturated n-carboxylic acid increased in the following order; formic acid> acetic acid>n-butyric acid>propionic acid. On the polycarboxylic acid, especially, malic acid showed 550$\sim$930% higher than control group. On the inorganic salts (0.5M), sodium perchlorate had the most hyperchromic effect and followed by sodium sulfate>sodium chloride>sodium phosphate, monobasic. Among the metal ions, both aluminium ion and cupric ion much more accelerated the anthocyanins degradation as compared with other metal ions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.6
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• pp.806-811
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• 2003

Effects of pH, temperature, light, sugars, organic acids, metal ions, ascorbic acid, thiamine nicotinic acid and pyridoxine on the stability of the color of the cranberry solution were investigated. The pH had marked influences on the color of the cranberry solution: i.e., the color of the cranberry solution was more intense at low pH. It showed characteristic bathochromic shift as the pH of the solution increased. The half-lives of olor value were 34 days at 37$^{\circ}C$, 91 mins at 9$0^{\circ}C$ and 29 mins at 12$0^{\circ}C$. Light gave an adverse effect to the stability of the color. The color degradation can be minimized by shielding the light from the cranberry solution. Among the sugars tested, fructose was the most deleterious followed by sucrose, galactose, maltose and glucose. Fumaric acid was found to be the most effective in stabilizing the color followed by citric acid, malic acid, acetic acid, while tartaric acid was found to be deleterious. Among the metal ions tested N $a^{+}$ and $Mg^{2+}$ were found to be effective in stabilizing the color, while M $n^{2+}$ was found to be the most deleterious followed by F $e^{2+}$, $K^{+}$ and $Ca^{2+}$. Ascorbic acid was found to be deleterious considerably followed by thiamine, while nicotinic acid and pyridoxine were found to be effective in stabilizing the color feebly.or feebly.