• Mycobiology
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• v.33 no.4
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• pp.223-229
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• 2005

A novel fungal strain Aspergillus sp. L117 that produced acid-stable and thermostable phytase was isolated on basis of the clearing zone on PSM plate and the ability of Na-phytate hydrolysis. The phytase of isolate showed a 3-fold higher activity than that of A. ficuun NRRL3135. The Aspergillus sp. L117 produced maximal level of phytase at initial pH of 5.0 and $30^{\circ}C$. The optimal pH and temperature for phytase activity were 5.5 and $50^{\circ}C$, respectively. The phytase showed totally stable activity after 20 min of exposure between 30 and $90^{\circ}C$, and even at $100^{\circ}C$. The highest level of residual phytase activity was obtained at pH 5.5, and still retained the stability at the broadest pH ranges (2.0 to 7.0) of all the aforementioned phytases. Storage stability of phytase was preserved over 96% of initial activities for 60 days at 4, -20, and $-70^{\circ}C$ and to retain even 70% of the initial activity at room temperature.

• Food Science and Biotechnology
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• v.16 no.4
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• pp.572-575
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• 2007

The angiontensin converting enzyme (ACE) inhibitory peptides were separated from beef sarcoplasmic protein extract and their amino acid sequences were identified as GFHI, DFHINQ, FHG, and GLSDGEWQ. The 4 peptides were synthesized in a laboratory and the ACE inhibitory activities of pep tides was measured after 2 months of storage at $4^{\circ}C$ under different pH conditions (6.0, 6.5, 7.0, 7.5, and 8.0) and the exposure of different temperatures (70, 80, 90, and $100^{\circ}C$) for 20 min to evaluate industrial use. No significant difference was detected by pH and temperature abuse for 20 min during storage. When the synthetic peptides were digested by pepsin, trypsin, and chymotrypsin, the ACE inhibitory activity was not changed. These results indicated that the 4 synthetic peptides with ACE inhibitory activity were pH-stable, heat-stable, and resistant to proteinases in gastro-intestinal tracts. Therefore, those 4 peptides can be used as a source for functional food product with various applications.

• Journal of the Korean Society of Clothing and Textiles
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• v.26 no.2
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• pp.263-269
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• 2002

This research was conducted to establish the efficient use of the colored rice bran fur dyeing textiles. To investigate the fabric dyeability of the colored rice bran extract, the anthocyanin pigments were extracted with water of different temperature ranges of 40 ~ 8$0^{\circ}C$ and were dyed on silk fabrics with different dyeing temperature $25^{\circ}C$~6$0^{\circ}C$, at acidic pH and neutral pH, respectively. Aluminum chloride was preheated with mordant K/S value and dyeing fastness of dyed silk fabrics were examined. The anthocyanins of the colored rice bran were stable and red color at acidic pH, red purple or purple blue at neutral pH, but unstable, blue color at alkaline pH. If extracting temperature and dyeing temperature of dyeing solution were higher, the dyeability was high, but the color of dyed fabric showed red tone. When extracting temperature was 8$0^{\circ}C$ and dyeing temperature of dyeing solution was 6$0^{\circ}C$, the dyeability was best. Without mordant, the dyeability of silk fabrics was higher in acidic pH than in neutral pH solution. With mordant, the dyeability was higher than without mordant, and also higher in acidic pH. Pretreatment of aluminum chloride resulted in the increase of color intensity and stability. The laundering fastness of dyed fabrics was good from grade 5 to grade 3-4. Because of the anthocyanins sensitivity on light radiation, the light fastness of dyed fabrics was poor from grade 3 to grade 1-2.

• Journal of the East Asian Society of Dietary Life
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• v.14 no.4
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• pp.355-362
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• 2004

Studies on extraction and color stability of carotenoids from astringent persimmon(Diospyros kaki) were performed to provide the basic information for the utilization of persimmon pigment as a new source of natural food colorant. The major carotenoids in astringent persimmon were beta-cryptoxanthin, lycopene and beta-carotene. Beta-cryptoxanthin was the first major pigment and lycopene the next. Total carotenoid content in persimmon calculated as beta-carotene equivalent was 107.4 $\mu\textrm{g}$/g. The data indicated that the astringent persimmon was a good source of carotenoid pigment. The physical and chemical stabilities of carotenoid from astringent persimmon were investigated at various conditions of temperature, pH and antioxidant. The effects of oxygen and light on the stability of carotenoid pigment has been investigated. The factors that cause the discoloration were visible light, temperature above 60, pH below 5 and oxygen. Especially, the carotenoid pigment was very sensitive to light and oxygen. Carotenoid stability was much improved with increasing nitrogen concentration in the atmosphere. Persimmon pigments have been found to be most stable at 5∼10. And tocopherol was the most effective inhibitor of the pigment discoloration.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.spc
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• pp.84-88
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• 2008

This study was carried out to develop the methods for efficient extracting and stabilization of anthocyanin pigments in black colored soybean. The optimum solvent concentration for the highest pigment extraction from seed coat of black colored soybean was 60% MeOH with 0.1% HCl in laboratory test. The higher temperature of the solvent until $60^{\circ}C$ led to better extraction efficiency of anthocyanin. The anthocyanin extracts maintained almost its stability in strong acidity area whereas it destroyed markedly over pH 4. Also anthocyanin extracts was stable for a while under weak light condition, but it showed rapid degradation of pigment color and markedly decreased HPLC value for anthocyanin content after one month storage days. In case storage temperature and instrument, glass vessel on low temperature ($4^{\circ}C$) was good storage condition among some treatments. And C3G was more stable than other pigments.

• The Korean Journal of Food And Nutrition
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• v.24 no.4
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• pp.559-566
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• 2011

The effects of pH and temperature on degradation of anthocyanin in purple-fleshed sweet potato cultivars(Mokpo No.62, Borami, Jami, Sinjami and Ayamurasaki) were determined at pH ranges of 1 to 5 and temperature ranges of 20 to $80^{\circ}C$. The anthocyanin contents of five sweet potato varieties were 3.9, 3.8, 4.7, 4.1, 4.2 mg/g of dried sweet potato, respectively. Degradations of anthocyanins at different pHs and temperatures followed the first-order reaction. Our results clearly showed that the anthocyanin stability of purple-fleshed sweet potato was dependent on the source of the sweet potato cultivars. Anthocyanin obtained from Borami showed the highest stability. The half-life of antocyanin degradation of purple sweet potato cultivars(Mokpo No.62, Borami, Jami, Sinjami and Ayamurasaki) at pH 3 were 22.2, 28.3, 26.3, 23.4, 22.7 days at $60^{\circ}C$, respectively. A significant decrease in anthocyanin stability was observed at temperatures above $40^{\circ}C$. Activation energies of purple-fleshed sweet potato cultivars at different temperatures were 54.67, 60.93, 71.73, 59.35, 62.28 kJ/mol, respectively.

• Food Science and Biotechnology
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• v.15 no.3
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• pp.453-457
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• 2006

Activity and stability of kiwifruit actinidine was determined in various conditions of pH, salt, and temperature using N-${\alpha}$-CBZ-lysine P-nitrophenyl ester as the substrate. Actinidine activity was low below pH 6, and undetectable below pH 3. The enzyme was stable in a pH range of 6.0-8.5. At $4^{\circ}C$ the enzyme was inactive in the presence of greater than 36% vinegar and in 2 M NaCl. Actinidine at $25^{\circ}C$ was unstable in 24% vinegar but stable in up to 3 M NaCl. With regard to freeze-thaw stability, actinidine retained 85% residual activity after being frozen at $-20^{\circ}C$ for 3 days. Based on Arrenius and Lineweaver-Burk plots, actinidine became unstable at greater than $45^{\circ}C$ with only 30% residual activity remaining after 6 min. The Km, kcat, and kcat/Km values of actinidine were $56\;{\mu}M$, 67/sec, and $1.2\;{\mu}M/sec$, respectively.

• Korean Journal of Food Science and Technology
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• v.34 no.4
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• pp.541-545
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• 2002

Stability of Monascus pilosus pigment was investigated under various conditions. The concentration of the pigments stored under air and sub-atmosphere (250 mmHg) for 30 days at room temperature decreased by 77.9% and 48.4%, respectively. The pigment solution was stable under temperature ranges of $20-80^{\circ}C$, pH 4-8, darkness and presence of KCl, NaCl, $CaCl_2$, $MgCl_2$, and $ZnCl_2$. In contrast, the pigment solution was relatively unstable, decreasing in concentration by 6.0 and 11.6% at 100 and $121^{\circ}C$, 15.5 and 13.7% at pH 3 and 9, 22.9 and 66.8% under fluorescence and sun light, respectively, and 20.2% in the presence of $AlCl_3$.

• Korean Journal of Poultry Science
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• v.15 no.1
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• pp.39-44
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• 1988

This study was undertaken to find out the effect of heating time and temperature, pH and NaCl concentration on heat sensitivity of egg albumen during heat treatment. Sharp increase of the turbidity and rapid decrease of the foaming power were observed when egg albumen was heated at above $60^{\circ}C$. Egg albumen became opaque when it was heated at $60^{\circ}C$ for above 13 minutes or at $65^{\circ}C$ for above 5 minutes. The turbidity was markedly increased at below pH 7 and the foaming power was largely decreased at around pH 4.0 by the heat treatment ($60^{\circ}C$, 5 min). The foam stability was slightly decreased at alkaline pH range by the heat treatment (60t, 5 min). The addition of NaCl up to 0.3M decreased the turbidity. There was no effect of NaCl addition on the foaming power, but the foam stability was decreased by the addition of NaCl at above 0.2M before and after the heat treatment ($60^{\circ}C$, 5 min).

• YAKHAK HOEJI
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• v.38 no.5
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• pp.488-495
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• 1994

To evaluate the feasibility of transmucosal delivery of leucine enkephalin (Leu-Enk) and its synthetic analog, $[D-Ala^2]$-leucine enkephalinamide (YAGFL), their physicochemical stabilities in aqueous buffered solutions were first investigated using a stability indicating high performance liquid chromatography. The degradation of Leu-Enk and YAGFL followed the pseudo-first-order kinetics. From the pH-rate profiles, it was found that the maximal stability of the two pentapeptides was at the pH of about 5.0. The shelf lives $(t_{90%})$ for the degradation of Leu-Enk and YAGFL at pH 5.0 and $40^{\circ}C$ were found to be 48.13 and 50.9 days, respectively. From the temperature dependence of the degradation, activation energies for Leu-Enk and YAGFL were calculated to be 13.61 and 13.47 kcal/mole, respectively. A higher ionic strength and a higher initial peptide concentration in buffered solution slowed the degradation of the two pentapeptides. The addition of 2-hydroxypropyl-${\beta}$-cyclodextrin into the peptide solution did not affect the stability significantly.