• 한국축산식품학회지
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• 제33권6호
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• pp.744-751
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• 2013

The objective of this study was to assess the physicochemical and sensory changes of a kefir manufactured by a two-step fermentation (MTY, $1^{st}$ step: $37^{\circ}C$ for 9 h; $2^{nd}$ step: $24^{\circ}C$ for 15 h) and compare it with kefirs produced by two conventional methods (GTY, fermentation at $37^{\circ}C$ for 24 h; KEY, $22^{\circ}C$ for 24 h). Rapid changes in pH and titratable acidity (TA) were observed in samples from all three manufacturing methods during fermentation process and storage period. Lactic acid bacteria (LAB) counts of MTY increased gradually up to 12 h of fermentation, reaching 9.28 Log CFU/mL, with maximum value observed in this experiment of 9.48 Log CFU/mL. The LAB counts of all samples decreased significantly during storage. The highest viscosity was observed for MTY (1750-1771 cPs), compared with the lowest viscosity observed for KEY (1250-1277 cPs). The viscosity of all samples increased slightly during storage (1250-1805 cPs, p<0.05), as well as carbon dioxide content (0.01-1.36%, p<0.05), except for GTY. The most significant increase in alcohol concentration during storage period was seen in MTY from 0.01% to 1.36% (p<0.05). MTY scored significantly higher in most items of the sensory analysis, indicating that the product manufactured by the two-step fermentation method is more acceptable compared with conventionally produced kefirs.

• 한국식품영양학회지
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• 제25권4호
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• pp.871-877
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• 2012

추출조건에 따른 귀리겨 ${\beta}$-glucan의 추출조건을 확립하기 위하여 추출온도($40{\sim}60^{\circ}C$), 추출용매의 에탄올 농도(0~20%) 및 pH(5~9)를 변수로 중심합성계획법으로 설계하여 ${\beta}$-glucan 추출특성을 조사하였다. 추출시간의 증가에 따라 ${\beta}$-glucan의 추출속도는 추출초기에 급격히 증가하였으나, 이후에는 완만하였다. 총괄물질전달계수는 $3.363{\sim}8.552{\times}10^{-6}cm/min$ 범위로 낮은 추출온도에서는 추출용매의 농도가 낮을수록, 높은 추출온도에서는 추출용매의 농도가 높을수록 증가하였지만 pH에 의한 영향은 적은 것으로 나타났다. 추출용매의 pH는 중성일 때보다 산성이나 알칼리성일 때 ${\beta}$-glucan의 추출량이 증가하였다. 추출조건에 따라서 ${\beta}$-glucan 수용액의 점도는 유의적인 차이를 보였으며, 총괄물질전달계수가 높을수록 crude ${\beta}$-glucan 수용액의 점도가 높게 나타났으며, 점도, 추출율 및 총괄물질전달계수의 상관관계를 분석한 결과, 각각의 요인들이 높은 양의 상관관계(p<0.01)를 나타내었다.

• 한국축산식품학회지
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• 제38권5호
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• pp.927-935
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• 2018

Various amounts of buckwheat powder (0%, 1%, 2%, and 3%) were added to emulsion-type pork sausages. The effects of buckwheat powder on the physicochemical characteristics of the emulsion type sausages, including proximate composition, cooking yield, viscosity, pH, instrumental color, texture profile analysis (TPA), and sensory evaluation, were determined. Increased levels of added buckwheat powder led to higher moisture (p<0.05), ash content (p<0.05 or >0.05), and cooking yield (p<0.05). However, the protein and fat contents of the sausage samples were lower (p<0.05) with higher levels of added buckwheat powder. The instrumental color and pH values were affected by the addition of buckwheat powder, which has a pH of 6.1 and associated color coordinates of $L^*=75.0$, $a^*=1.3$, and $b^*=8.7$. Meat batter with 3% buckwheat powder was shown the highest (p<0.05) viscosity indicating great formation of emulsion. There were no significant differences in the TPA among the treated samples. The viscosity value increased with increasing cooking yield in the batter ($r^2=0.7283$) i.e. the correlation coefficient between the two measurements was very high and positive. For sensory traits except for tenderness, the highest scores (p<0.05) was detected on sausages with 3% added buckwheat powder by a panel. These results suggest that the addition of 3% buckwheat powder to emulsion-type sausages produces a more beneficial meat product, with a lower fat content, greater formation of emulsion and no adverse effects on sensory properties.

• 한국세라믹학회지
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• 제43권4호
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• pp.203-206
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• 2006

Polyacrylonitrile (PAN) nanofibers, which are pH-sensitive and exhibit soft actuation as a linear actuator and artificial muscles, were prepared by electrospinning to investigate the effect of viscosity on the morphology of PAN fibers. Experimental results revealed that higher viscosity is critical for the formation of unbeaded nanofibers because surface tension is almost constant throughout the experiment. Uniform, smooth, and continuous fibers with diameters of about 700 nm were achieved for the 10 wt% PAN fibers at a flow rate of 0.5 mL/h and an electric field of 0.875 kV/cm.

• 산업기술연구
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• 제20권A호
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• pp.39-44
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• 2000

Highly viscous biopolymer from alkali-tolerant Bacillus sp. was purified and its solution properties were investigated. The intrinsic viscosities for crude biopolymer and biopolymers purified by dialysis or CPC(cetylpyridinium chloride) treatment were 58.24, 73.60 and 42.18 dL/g, respectively. The intrinsic viscosity of biopolymer showed the maximum value at the neutral pH but it was decreased remarkably at the alkaline or acidic pH. Biopolymer exhibited the property of polyelectrolyte, showing the sharp decrease of intrinsic viscosity by the addition of NaCl. Intrinsic viscosity of dilute solution at the low NaCl concentration was exponentially dependent on temperature and its temperature dependency was increased with NaCl concentrations. The chain stiffness, coil overlap parameter, and critical concentration were 0.09, 5.25 and 0.07g/dL, respectively. Temperature dependency on intrinsic viscosity of biopolymer solution was different each other at $45^{\circ}C$. Flow activation energies at temperatures above $45^{\circ}C$ were constant, while those at temperatures below $45^{\circ}C$ increased with increase of added NaCl concentration.

• 한국식품영양학회지
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• 제12권5호
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• pp.484-489
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• 1999

Rosting conditions for improvement of viscosity and sensory properties of sea tangle extracts were investigated. The supernatant % solid yield and crude protein yield were increased by increasing of roasting temperature and times. The highest contents of algin was obtained in roasting temperature of 175$^{\circ}C$ ash contents were increased by roasting temperature increasing. Viscosities of sea tangle extract were significantly decreased by increasing of roasting temperature and time upto 175$^{\circ}C$ and 10 mins more than further roasting conditions. The pH of sea tangle extracts slightly decreased from 5.94 to 5.83 in the roasting of 15$0^{\circ}C$ however at temperature more than 175$^{\circ}C$ its pH was increased by increasing of temperature and time. According to increase of roasting temperature and time Lightness (L value) were significantly decreased and redness (a value) and yellowness (b value) reached the highest value in the roasting of 20$0^{\circ}C$ 15 min. or 175$^{\circ}C$ 30 min and after that its value were decreased. The odor characteristics showed that sea tangle extract prepared by roasting of 175$^{\circ}C$ 10mins was slightly reduced in intensity of savory and seaweed taste but significantly low in intensity of nauseous taste and high in intensity of roasted taste and accetability. Overall data suggested 175$^{\circ}C$ 10min was the most effective roasting conditions for improvement of viscosity and sensory properties of sea tangle extract.

• 한국응용과학기술학회지
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• 제27권2호
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• pp.99-106
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• 2010

We have investigated the rheological behaviours of emulsions containing polymers. The polymers used in this study were polyacrylamide and carboxy vinyl polymer. The emulsion with polyacrylamide shows better prior preference than that with carboxy vinyl polymer on the skin texture. In the toxicity test, such as, LLNA cell toxicity, skin organ culture and human patch test, polyacrylamide was the appropriate materials for the cosmetics. The viscosity of polyacrylamide shows maximum value in neutral pH and good stability against temperature. The decreasing effect of viscosity against salt was not good enough but showed a better result than that of carboxy vinyl polymer. Two times the amount of polyacrylamide should be used for the formation of a similar viscosity of carboxy vinyl polymer. Yield value of polyacrylamide was low and the effect for the stabilizing emulsions was also low.

• Bulletin of the Korean Chemical Society
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• 제3권3호
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• pp.83-88
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• 1982

Viscosity and zeta-potential of 11.0 wt. % aqueous bentonite suspension containing various electrolytes and hydrogen-ion concentration were measured by using a Couette type automatic rotational viscometer and Zeta Meter, respectively. The effects of pH and elcctrolytes on the rheological properties of the suspension were investigated. A system, which has a large zeta-potcntial, has a small intrinsic relaxation time ${\beta}$ and a small intrinsic shear modulus $1/{\alpha}$ in the Ree-Eyring generalized viscosity equation, i.e., such a system has a small viscosity value, since ${\eta}={\beta}/{\alpha}$. In general, a stable suspension system has large zeta-potential. The stability condition of clay-water suspension can be estimated by viscometric method since stable suspension generally has small viscosity. The correlation between the stability, viscosity and zeta-potential has been explained by the Ree-Eyring theory of viscous flow.

• 한국식품조리과학회지
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• 제22권2호
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• pp.111-121
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• 2006

The aim of this study was to investigate the possibility of producing goods evaluating the preservation of DSG, PSG, DST and PST, all of which were the most preferred according to the results of sensory evaluation of some sauces made of Demi-glace sauce and a Teriyaki-applied sauce. The pH of normal Demi-glace sauce, at 5.2, was the highest among these sauces. The Teriyaki-applied Demi-glace sauce was the second with pH 5.12 DSG was the lowest. The pH didn't change significantly according to preservation. However, the degree of PSG's pH was lowered by the time period of preservation. DGST didn't changed a lot apart from being a bit morewatery (12.40) after three-week storage. It seemed that the viscosity of the normal sauces, checked after 10 sec, decreased. At 20 sec there were no differences among these sauces. After making 10 applied sauces and evaluating them, DSG, PSG, DST and PST gained the highest preference and the application of Teriyaki sauce was evaluated favorably. According to the preservation test. the sensory evaluation didn't seem to decrease within 2 weeks which demonstrated that the other physicochemical products were unaffected. Therefore, an improvement following more than two-week preservation is expected in t case of rigid store regulation.

• 대한화학회지
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• 제37권2호
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• pp.249-254
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• 1993

N-p-nitrophenyl poly(m-phenylene isophthalamide)는 poly(m-phenylene isophthalamide)를 디메틸술폭사이드(DMSO) 용매속에서 수소화나트륨(NaH)과 반응시킨 후, 1-fluoro-4-nitrobenzene을 첨가하여 43 wt%를 얻었다. 고유점성도는 폴리머를 98% 황산에 녹여 $30^{\circ}C$에서 측정하였으며 그 값은 0.606g/cm${\cdot}$sec(0.125g/25ml)였다. Poly(m-phenylene isophthalamide) 합성에 있어서, 1,3-페닐디아민은 트리에틸아민과 트리에틸아민·염화수소가 있는 클로로포름 용매속에서 클로로이소프탈산과 반응에 의해 얻어졌다. 고유 점성도 값은 같은 조건에서 0.560g/cm${\cdot}$sec 였다. N-p-nitrophenyl poly(m-phenylene isophthalamide)의 치환비율은 $^1H-NMR$ integration에 의해 16.7~47.0%였다. 고유점성도가 큰 poly(m-phenylene isophthalamide)를 사용했을 때는 치환비율이 낮았다.