• 한국식품과학회지
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• 제23권3호
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• pp.355-359
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• 1991

글루타민산 나트륨(MSG)의 열안정성을 조사하기 위하여 가열온도 및 pH를 변화시키면서 가열 중 MSG의 분해정도를 비교하였다. 가열온도와 pH의 범위는 각각 $100{\sim}120^{\circ},\;4{\sim}9C$로 하였고, MSG는 2% 용액으로 만들었으며 가열 중 잔류 MSG 농도를 HPLC로 측정하였다. 그 결과 pH 4와 $120^{\circ}C$의 3시간 가열로 약 73% MSG가 감소한 반면, $100^{\circ}C$에서의 3시간 가열은 12% 정도만이 감소함을 보였다. 가열온도와 pH에 따른 초기 MSG의 분해속도와 분해 속도상수{(%MSG/log(hrs)}를 비교한 결과 $110^{\circ}C$와 $120^{\circ}C$에서의 초기 분해속도는 pH 4가 가장 빨랐으며 분해 속도상수도 상당히 높은 값을 보였다. 분해가 가장 적었던 pH 범위는 $pH6{\sim}8$ 범위였다. 또한 가열온도에 영향을 가장 많이 받았던 pH 4와 pH 5의 MSG 열분해 속도상수와 1/T의 관계에서 계산된 활성화에너지는 각각 18.3 kcal/mole과 9.2 kcal/mole이었다.

• 한국축산식품학회지
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• 제31권5호
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• pp.727-730
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• 2011

The effects of various NaCl levels (0, 0.3, and 0.6 M) and pH values (pH 5.0, 5.5, 6.0, and 6.5) on the emulsifying and gelling properties of pork myofibrillar protein (MP) were assessed. The emulsion stability index (ESI), emulsifying activity index (EAI), and creaming index were measured at a 1:20 ratio of MP to corn oil. The EAI and ESI of pork MP showed maximum values at pHs 6.0 and 6.5 and at 0.3 M NaCl, resulting in better emulsion properties. Additionally, the cooking yield (CY) and gel strength (GS) of emulsified MP gel were measured at an MP: corn oil ratio of 1: 2; GS increased with increasing levels of salt. At 0.6 M NaCl, GS decreased with decreasing pH from 5.5 to 6.5. GS and gelling properties were optimal at pH 5.5 in 0.6 M salt. The highest CY was observed at 0.6 M NaCl, regardless of the pH value. However, increasing pH increased CY at salt levels of 0 and 0.3 M. These results indicate that NaCl and pH profoundly affected the emulsified MP system. Future work will be conducted on the rheological properties of the pork emulsified system as affected by adding non-meat protein.

• 한국축산식품학회지
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• 제30권5호
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• pp.717-721
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• 2010

The objective of this study was to evaluate the inhibition of Listeria monocytogenes growth by oleanolic acid under sublethal stresses of NaCl and pH. L. monocytogenes ATCC15313 (6 log CFU/mL) was inoculated in microplate wells containing brain heart infusion (BHI) broth supplemented with oleanolic acid in various amounts (0, 0.25, 0.5, 1.0, 1.5, 2.0, and $4.0\;{\mu}g/mL$), and different pHs (5 and 7) and NaCl concentrations (0, 3, and 6%), followed by incubation under accelerated storage condition ($37^{\circ}C$, 48 h). The optical density (OD) of the samples was measured at 0, 6, 12, 24, and 48 h at 600 nm. After the lag phase duration was observed at the early stage of incubation, the OD values of L. monocytogenes significantly increased (p<0.05) in BHI broth formulated with 0 and 3% of NaCl during accelerated storage at pH 5 and 7. However, the growth of L. monocytogenes in 6% NaCl and at less than $0.5\;{\mu}g/mL$ of oleanolic acid had no growth at pH 5 and only gradual growth at pH 7. Moreover, L. monocytogenes generally had lower OD values as the concentrations of oleanolic acid increased. As expected, the OD values of L. monocytogenes were generally higher (p<0.05) at pH 7 than at pH 5. These results indicate that oleanolic acid should be useful in inhibiting the growth of L. monocytogenes.

• Investigative Magnetic Resonance Imaging
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• 제18권1호
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• pp.52-58
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• 2014

목적: 임상용 MRI에서 마우스 종양의 pH 측정을 위한 $^1H-^{31}P$ RF 코일 시스템을 개발하고 팬텀을 이용하여 pH 값의 정확도를 시험하고자 한다. 대상과 방법: 마우스 종양 연구를 위한 표면형 $^1H$ 및 $^{31}P$ radio frequency (RF) 코일을 개발하였다. 두 코일을 서로 수직이 되도록 설치하여 두 코일간의 상호인덕턴스를 0으로 하였다. 다양한 pH 값을 가진 팬텀으로부터 $^{31}P$ MR 스펙트럼을 얻어 Henderson-Hasselbalch equation을 이용하여 pH를 구하였다. $^{31}P$ 스펙트럼으로부터 얻은 pH값은 pH meter를 사용하여 직접 구한 pH값과 비교한다. 결과: $^1H-^{31}P$ RF 코일 상호간 coil coupling (S12)은 각각 -73.0, -62.3 dB로 충분히 분리 되었다. 균일한 팬텀으로부터 얻은 $^1H$ 영상의 signal-to-noise ratio (SNR)는 약 300 이상이며, in vivo 고해상도 마우스 영상을 얻을 수 있었다. $^1H$ 신호가 분리된 $^{31}P$ MR 스펙트럼으로부터 얻은 pH값은 pH meter로 직접 측정하여 얻은 값과 약 97% 상관관계를 가졌다. 결론: 본 연구에서 개발한 임상 MRI 장비용 $^1H-^{31}P$ RF 코일 시스템으로부터 정확한 pH를 구할 수 있었다. 본 코일 시스템은 31P 이외의 다른 핵 MRS 혹은 MRI에 적용 가능할 것으로 기대된다.

• 한국재료학회지
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• 제24권11호
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• pp.578-584
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• 2014

To synthesize Sn nanoparticles (NPs) less than 30 nm in diameter, a modified polyol process was conducted at room temperature using a reducing agent, and the effects of different pH values of the initial solutions on the morphology and size of the synthesized Sn NPs were analyzed. tin(II) 2-ethylhexanoate, diethylene glycol, sodium borohydride, polyvinyl pyrrolidone (PVP), and sodium hydroxide were used as a precursor, reaction medium, reducing agent, capping agent, and pH adjusting agent, respectively. It was found by transmission electron microscopy that the morphology of the synthesized Sn NPs varied according to the pH of the initial solution. Moreover, while the size decreased to 11.32 nm with an increase up to 11.66 of the pH value, the size increased rapidly to 39.25 nm with an increase to 12.69. The pH increase up to 11.66 dominantly promoted generation of electrons and increased the amount of initial nucleation in the solution, finally inducing the reduced-size of the Sn particles. However, the additional increase of pH dominantly induced a decrease of PVP by neutralization, which resulted in acceleration of the agglomeration by collisions between particles.

• 한국축산식품학회지
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• 제40권2호
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• pp.254-261
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• 2020

The aim of this study was to evaluate quality characteristics of pork myofibrillar protein (MP) added with cornstarch as affected by different pH values and salt cocnentrations. MP mixtures were prepared with three different pH values (pH 6.00, 6.25, and 6.50) and three different salt concentrations (0.15, 0.30, and 0.45 M). Cooking yield (CY), gel strength, viscosity, and scanning electron microscopy were measured to evaluate characteristics of MPs. CYs of MPs with cornstarch at above pH 6.25 or salt 0.30 M were increased compared to those at pH 6.00 or salt 0.15 M. However, gel strengths of MPs at salt 0.45 M were higher than those at salt 0.30 M. In microstructure analysis, MP gels with increasing pH value and salt concentration showed compact and uniform structure. Thus, MP gels with pH 6.25 and salt concentration of 0.30 M would be better for manufacturing meat products containing cornstarch to increase their water holding ability.

• 한국축산식품학회지
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• 제18권2호
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• pp.157-163
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• 1998

This study was carried out to examine that pepsin-hydrolyzed bovine lactoferrin has applicabilities which are market milk and dairy products. The stability of pepsin-hydrolyzed bovine apo-lactoferrin and the change of its antibacterial character has been studied under various method for pasteurization (LTLT; 65$^{\circ}C$ / 30min., HTST ; 75$^{\circ}C$ / 15sec., UHT ; 135$^{\circ}C$ / 3sec.) and pH Values (pH 2.0, pH 4.0, pH 6.8). The ehated samples were assayed for minimal bacteriocidal concentrations (MBCs) and bacteriocidal effect against E. coli. The results obtained were summarized as follows: After fractionation of pepsin-hydrolyzed bovine lactofeerin by gel filtration. several peptide fractions were found that had strong antibacterial activity. SDS-PAGE showed that the one of these fractions with strong antibacterial activity, which had a molecular mass a range of 30∼33KDa. The MBCs for pepsin-hydrolyzed bovine lactoferrin fraction No. 2 against E. coli required to cause complete inhibition of growth varied within the range of 200∼400 $\mu\textrm{g}$/ml, depending on heat treatments and pH conditions. The peptide fraction No. 2 showed strong bacteriocidal activity against E. coli at LTLT and HTST treatments under acidic pH conditions. and was reduced activity at UHT treatment under pH 6.8 condition.

• 방사성폐기물학회지
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• 제19권1호
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• pp.1-7
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• 2021

The pH dependence of sorption distribution coefficient (Kd) of Np(IV) on MX-80 in Ca-Na-Cl type solution with the ionic strength of 0.3 M, which was similar to one of the reference groundwaters in crystalline rock, was experimentally investigated under the reducing conditions. The overall trend of Kd on MX-80 was independent of pH at 5 ≤ pH ≤ 10 but increased as pH increased at pH ≤ 5. The 2-site protolysis non-electrostatic surface complexation and cation exchange model was applied to the experimentally measured pH dependence of Kd and the optimized surface complexation constants of Np(IV) sorption on MX-80 were estimated. The values of surface complexation constants in this work agreed relatively well with those in the Na-Ca-Cl solution previously evaluated, suggesting that compared to Na+, the competition of Ca2+ with Np(IV) for surface complexation on MX-80 was not much strong in Ca-Na-Cl solution. The sorption model well predicted the pH dependence of Kd values but slightly overestimated the sorption at the low pH region.

• KSBB Journal
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• 제4권2호
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• pp.65-68
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• 1989

누에 번데기의 단백질 추출 조건을 규명하고자 온도, ph및 시간 변화에 따라 추출된 단백질의 총 질소함량을 Kjeldahl법과 원소 분석기를 이용한 결과는 다음과 같다. 1. 누에 번데기의 초단백질 : 23.34%, 조지방 : 15.61%이나, 2. 온도 변화에 따른 ph 4에서 1시간 추출시 6$0^{\circ}C$:6.76%, 8$0^{\circ}C$:7.94%, 10$0^{\circ}C$:8.67%이고 C.H.N corder의 분석결과는 6$0^{\circ}C$:8.08%, 8$0^{\circ}C$:9.52%, 10$0^{\circ}C$:9.72%로서 두 가지 방법에서 수치는 다르지만 온도 상승에 따라 수용성 질소계수가 증가하는 경향임을 알 수 있다. 3. pH변화에 따른 8$0^{\circ}C$에서 1시간 추출시 pH 4:7.94%, pH 6:8.96%, pH : 8:9.70%, pH : 10:10.67%, pH : 12:10.98%로 온도 상승과 같이 pH증가에 따라 증가하는 경향을 보이고 있다. 4.추출시간의 변화에 따른 10$0^{\circ}C$에서 pH 4인경우 1시간:8.67%, 2시간:9.23%, 3시간:9.76%이고, C.H.N. corder의 결과는 1시간:9.72%, 2시간:10.06%, 3시간:10.83%로서 추출 시간이 늘어남에 따라 증가되는 경향을 보이고 있다.

• Preventive Nutrition and Food Science
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• 제13권4호
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• pp.306-312
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• 2008

This study investigated the influence of pH on the color development of melanoidins formed from amino acid enantiomer model systems. For this, the color development was evaluated by measuring browning at 420 nm and color measurements by spectrophotometry and colorimetry. The browning and browning index showed no difference according to the type of amino acid enantiomers, while that formed from the D-Asn system was the only difference according to pH level. The tristimulus value of melanoidins formed from all model systems was located on a dominant wavelength of 475 nm, the blue zone of the diagram. In addition, the $L^*$, $a^*$, $b^*$, $C^*_{ab}$ values, and ${\Delta}E^*$ index on the basis of the type of amino acid enantiomers, the differences were markedly found at pH 4.0. At pH 7.0, significantly differences were found in the $L^*$, $a^*$, $b^*$ values, and ${\Delta}E^*$ index and not in the case of the lysine enantiomers. In addition, at pH 10.0, the differences were found in the $a^*$ and $b^*$ values from the lysine enantiomers and $C^*_{ab}$ value from the asparagine enantiomers. Therefore, the color development of melanoidins was influenced by the type of amino acid enantiomers and pH levels. Especially, it is thought that the $a^*$ and $b^*$ values can be used to explain the differences among the amino acid enantiomers in the color development of melanoidins.