• Korean Journal of Food Science and Technology
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• v.23 no.3
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• pp.355-359
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• 1991

Effects of temperature and pH on thermal degradation of monosodium glutamate(MSG) were investigated during heating of 2% MSG solution at $100{\sim}200^{\circ}C\;and\;pH\;4{\sim}9$. The results showed that the degradation of MSG was very significantly affected by heating temperature and pH. Three hours of heating at $pH\;4\;and\;120^{\circ}C$ resulted appr. 73% MSG degradation while 3 hours at $100^{\circ}C$ decreased only 12%. The comparison study of initial rate of MSG degradation and degradation rate constants showed the highest degradation rate and rate constant and low values in the range of $pH\;6{\sim}8{\sim}$. The values of activation energy calculated from linear relationship of rate constants and 1/T were 18.3 and 9.2 kcal/mole for pH 4 and 5, respectively.

• Bulletin of the Korean Chemical Society
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• v.23 no.6
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• pp.845-851
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• 2002

The synthesis of the intramolecular donor - stabilized silyl and germyl complexes of the type ($Cab^c.p) MMe_2X$ (2a:M=Si, X=Cl;2b;M= Ge, X=Cl;2e;M=Si,X=H) was achieved by the reaction of $LiCab^c,p$ (1) with $Me_2SiClX$ and $Me_2GeCl_2$ respectively. The intramolecular M←P interacion in 2a-2c is provided by $^1H$, $13^C.$, $31^P$ and $29^Si$ NMR spectroscopy. The salt elimination reactions of dichlorotetramethyldisilane and -digermane with 1 afforded the $bis(\sigma-carboranylphosphino)disilane$ and disgermane [$(Cab^C.P)MMe_2]_2(4a;M$ = Si;4b: M=Ge). The oxidative addition reaction of 4a-4b with $pd_2(dba)_3CHCl_3afforded$ the bis(silyl)-and bis(germyl)-palladium complexes. The chloro-bridged dipalladium complexes were obtained by the reaction of 2a-2b with $pd_2(dba)_3CHCl_3$ The crystal structures of 5a and 7b were determined by X-ray structural studies.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.2
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• pp.212-218
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• 2006

Changes of paralytic shellfish poison (PSP) contents, toxicity and toxin composition with pH and storing periods at different temperature in toxic blue mussel, Mytilus edulis, were tested by using fluorometric HPLC method. Toxicity at pH 3 was the highest as 14.1 MU/g $(100\%)$ and showed 12.9 MU/g $(92.1\%)$ at pH 5, 9.0 MU/g $(63.8\%)$ at pH 7, 3.6 MU/g $(25.5\%)$ at pH 9 and 0.8 MU/g $(5.7\%)$ at pH 10 which suggested PSP was unstable at alkaline conditions. The decrease in toxicity during storage days was depend on pH and temperature. The toxicity markedly decreased until during the first S day storage $(19.9\~65.3\%)$ at all pH (3, 5, 7, 9) and temperature (30, 5, $-20^{\circ}C$), but, slightly decreased after then till to 30 days. C group toxin (C1 and C2) was the major components and other toxins such as GTX 1,2,3,4, STX and dcSTX were detected. Among the 8 toxins, GTX1,4, dcSTX and STX were firstly decreased according to the decreasing the toxicity at all processing conditions. The toxicity in blue mussel (14.1 MU/g) were able to remove by heating over 10 minutes at pH higher than 7.

• KSBB Journal
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• v.15 no.4
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• pp.359-365
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• 2000

Three lactic acid bacteria (C-1 K-3 and T-1 strain) were isolated from Nuruk and characterized subsequently. They were useful strains for production of lactic acid and their growth was inhibited at 10% ethanol pH 4 These strains were identified as lactococcus lactis subsp. lactis NR C-1 Leuconostoc mesenteroides subsp. mesenterides NR K-3 and pediococcus pentosaceus NR T-1 respectively by morphological physiological and biochemical characterization Lac lactis subsp lactis NR C-1 showed the highest lactic acid productivity. Leu measenteroides subsp mesenteroides NR K-3 showed stable lactic acid productivity and its growth was inhibited at pH 4. P pentosaceus NR T-1 had lower lactic acid productivity than the other two bacteria but it could not grow at 10% ethanol pH 4 The lactic acid productivity of these three strains in MRS broth were higher than that in Skim milk media the optimum pH and temperature for the lactic acid production of the three strains were 30-32$^{\circ}C$ and pH 6.0∼6.8 Glucose was the optimal carbon souorce for the lactic acid production. In terms of antagonism lac lactis subsp lactis NR c-1 showed somewhat inhibitory efects against some Gram positive rod and cocci such as Lactobacillus brevis and Streptococcus mitis. And Leu mesenteroides subsp mesenteroides NR K-3 showed the inhibitory effects against Streptococcus mitis but P. pentosaceus NR T-1 didn't show any inhibitory effects against tested strains.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.2
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• pp.385-399
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• 1997

The purpose of this experiment was to determine the effects of etching with a Nd : YAG Laser on dentin, or porcelain surface on the bond strength with composite resin. The dentin specimens were devided into the following 4 groups. D1 : No treatment D2 : Etched with 10% phosphoric acid D3 : Laser etchded with 1W, 20PPs D4 : Laser etched with 2W, 20PPS The procelain specimens were devided into the following 4 groups. P1 : diamond roughened P2 : etched with HF acid P3 : Laser etched with 2W, 20PPS P4 : Laser etched with 3W, 20PPS All specimens were veneered with resin. One half of the specimens were stored in $37^{\circ}C$ water for one day and the other half were thermocycled 1000 times at temperature of $5^{\circ}C\;to\;55^{\circ}C$ at 20 seconds intervals. After that, the bonding strength of composite resin to the dentin and porcelain was measured. The surface treated state and fractured state were observed with SEM. The following results were obtained. 1. In the dentin specimens, the bond strength of group D2 was highter than that of groups D1 and D3 in the case of the specimens stored in $37^{\circ}C$ water for one day, there was a statistically significant difference between group D2 and D1, D3 (P<0.05). The bonding strength of the specimens that were thermocycled decreased in the following order : group D2,D4,D3 and then D1. 2. In the porcelain specimens, the bonding strength of groups P1,P2 were higher than that of group P3 in the case of the specimens stored in $37^{\circ}C$ water for one day (P<0.05). The bonding strength of the specimens of being thermocycled decreased in the following order : group P2,P1,P4 and then P3. 3. The groups of high bond strength had a rougher surface and a high level of microporosity with SEM findings.

• Food Science of Animal Resources
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• v.31 no.4
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• pp.588-595
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• 2011

In this study, the effects of red ginseng extracts (RGE), which has been used as an antioxidant and antimicrobial agent, on pork sausage were evaluated. The treatments were as follows; addition of 0.01% sodium ascorbate (V), 0.5% RGE (T1), 1.0% RGE (T2) and 1.5% RGE (T3) to the basal formula (C). T3 had a significantly higher pH, cooking loss and yellowness ($CIEb^*$) and lower lightness (CIE $L^*$) and redness (CIE $a^*$) than the other samples. The hardness and surface hardness values of 1.5% RGE treated sample were significantly lower (p<0.01) than those of C. However, the cohesiveness values of the RGE samples were higher than the others (p<0.05). In the sensory evaluation, no significant differences in color, taste, texture, juiciness and acceptability were observed among the tested samples, while, the aroma scores of T2 and T3 were higher than those of the C and V samples (p<0.05). The TBARS values of RGE treated groups were higher (p<0.05) than the C sample after 1, 2 and 3 weeks of storage; however, this value did not increase with storage time (p>0.05). When the RGE concentration was high, the reduction in total plate counts and VBN value at week 3 and 4 of storage (p<0.01) decreased. In conclusion, red ginseng extracts seemed to have a positive impact on lipid oxidation, aroma and the microbial characteristics of pork sausage.

• Food Science of Animal Resources
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• v.31 no.4
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• pp.551-556
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• 2011

The objective of this study was to determine the resistance of Cronobacter sakazakii in acidic environments. The D-values of CAFM2 (ATCC 29544), EB 1, EB 5, and EB 41 at pH 2.5 in TSB were significantly (p<0.05) higher when cells were adapted at pH 4.5 in TSB for 5-h then when cells were not adapted at pH 4.5 in TSB. The D-values of CAFM2, EB1, and EB 41 at pH 2.5 in TSB were significantly (p<0.05) higher when cells were adapted at pH 4.5 in TSB for 10-h then when cells were not adapted at pH 4.5 in TSB. The D-values of CAFM2 and EB1 at pH 2.5 in TSB were significantly (p<0.05) higher when cells were adapted at pH 4.5 in TSB for 24-h then when cells were not adapted at pH 4.5 in TSB. The adaptation of C. sakazakii to mild acidic environments may result in increased resistance to severe acidic environments. The D-values of all test strains at pH 2.5 in TSB were significantly (p<0.05) higher when cells were cultured at pH 4.5 then when they were cultured at pH 7.2 in TSB. These data indicate that cells cultured in mildly acidic environments may result in increased resistance to severe acidic environments. The acid adaptation of C. sakazakii showed an increased resistance to acidic environments. The acid adaptation response of C. sakazakii has important implications for food safety, which should be considered when food preservation measures are developed.

• Journal of Animal Science and Technology
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• v.48 no.6
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• pp.861-870
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• 2006

This study was conducted to examine the effects of supplementing coated vitamin C+E with cottonseed on rumen fermentation and body weight gain, blood metabolites and hormone concentrations in Hanwoo steers fed fermented feedstuff. Experiments were done with two treatment groups, T1 without any supplements and T2 supplemented with coated vitamin C+E and cottonseed. Ruminal pH was lower in T2 than in T1 at 3h after morning feeding (p<0.05), but was higher in T2 than in T1 at 6 and 9h after morning feeding (p<0.05). Ruminal ammonia concentration was higher in T2 than in T1 for 12h after morning feeding (p<0.05). Concentrations of acetate, propionate, butyrate and total-VFA were higher in T2 than in T1 at 3h after morning feeding (p<0.05), but were lower in T2 than in T1 at 9 and 12h after morning feeding (p<0.05). Average daily gain and concentrations of blood metabolites and hormones between T1 and T2 were similar. Results indicate that supplementation of coated vitamin C+E and cottonseed to fermented feedstuff affects on ruminal pH, ammonia and VFA. But it has no influences on body weight gain and concentrations of blood metabolites and hormones in Hanwoo steers.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.9
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• pp.1361-1366
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• 2008

One-hundred and twenty Ischia grey rabbits, traditionally raised in pits, were equally divided after weaning (32 days) into three groups: group C, housed in cages (4 rabbits/cage) and fed a commercial concentrate; group GF, housed as C group and fed grasses collected on the island and crushed faba beans supplemented with an appropriate mineral vitamin mix; group P, housed in pits (8 rabbits/pit) and fed as GF group. Feed intake was recorded daily and live weight monthly up to slaughter (92 days). At slaughter, 10 rabbits per group were used to measure carcass and meat traits. The carcasses were weighed and measured according to the standard procedures and meat samples from the Longissimus dorsi and left hind leg were analysed for water holding capacity and chemical composition, respectively. During the entire trial, group C consumed significantly (p<0.01) a higher quantity of feed than the other groups (126.1 vs. 63.4 and 66.5 g/d, resp. for groups C, GF and P) and at slaughter showed a significantly (p<0.01) higher body weight (2,529.7 vs. 1,324.4 and 1,375.4 g, resp. for groups C, GF and P). Significant differences (p<0.01) were found also for dressing out percentage (68.6 vs. 66.6 and 66.9%, resp. for groups C, GF and P) and for meat chemical composition, in particular lipid percentage (4.13 vs. 1.84 and 1.93%, resp., for groups C, GF and P, p<0.01) and moisture (73.7 vs. 76.4 and 76.3%, resp. for groups C, GF and P, p<0.01). The results suggest the opportunity to obtain heavier animals raised in the pits if their diets were integrated with commercial feed.

• Korean Journal of Environment and Ecology
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• v.28 no.5
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• pp.566-573
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• 2014

Decay rate and nutrient dynamics during leaf litter decomposition of deciduous broad leaf Quercus mongolica and evergreen needle leaf Pinus densiflora were investigated for 69 months from December 2005 to September 2011 in Mt. Worak National Park as a part of National Long-Term Ecological Research Program in Korea. Percent remaining weight of Q. mongolica and P. densiflora leaf litter after 69 months elapsed was $35.4{\pm}2.3%$ and $16.1{\pm}1.3%$, respectively. Decomposition of P. densiflora leaf litter was significantly faster than that of Q. mongolica leaf litter. Decay constant (k) of Q. mongolica and P. densiflora leaf litter after 69 months elapsed was 5.97 and 10.50, respectively. Initial C/N and C/P ratio of Q. mongolica leaf litter was 43.1 and 543.9 respectively. After 69 months elapsed, C/N and C/P ratio of decomposing Q. mongolica leaf litter decreased to 8.7 and 141.2, respectively. Initial C/N and C/P ratio of P. densiflora leaf litter was 151.2 and 391.4, respectively. After 69 months elapsed, C/N and C/P ratio of decomposing P. densiflora leaf litter decreased to 22.9. and 136.5. respectively. Initial concentration of N, P, K, Ca and Mg in leaf litter was 9.30, 0.23, 2.36, 3.14, 1.11 mg/g in Q. mongolica, and 3.02, 0.09, 1.00, 3.84, 0.62 mg/g in P. densiflora, respectively. Initial concentration of N and P in Q. mongolica leaf litter was significantly higher than those in P. densiflora. After 69 months elapsed, remaining N, P, K, Ca and Mg in decomposing leaf litter were 73.8, 60.9, 17.2, 20.3, 35.1 % in Q. mongolica, and 69.5, 75.3, 12.3, 10.9, 10.8 % in P. densiflora, respectively.