• 한국식품영양과학회지
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• 제42권8호
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• pp.1204-1210
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• 2013

총 산도 10% 이상의 시판 고산도 식초를 원료(사과농축액, 맥아엑기스, 액상포도당 및 현미당화농축액)와 산도(2배 및 3배)에 따라 구입하여 이화학적 품질 및 항산화 특성을 확인하였다. 총산 함량은 2배 식초(12.10~13.41%)와 3배 식초(18.15~18.36%) 사이 유의적인 차이를 나타내었고, 식초의 당도 및 환원당 함량은 각각 $7.00{\sim}10.80^{\circ}Brix$ 및 1.32~3,885.90 mg% 범위로 확인되었으며 일정한 경향은 관찰되지 않았다. 고산도 식초의 유리당으로 fructose 및 glucose가 주로 확인되었고, 2배 식초의 경우 3배 식초에 비해 종류와 함량 측면에서 비교적 우수한 것으로 분석되었다. 식초의 품질지표인 acetic acid는 모든 식초에서 7,171~14,762 mg% 함량으로 분석되었고, oxalic acid의 경우 시판 고산도 식초에서는 확인할 수 없었다. 맥아엑기스를 사용한 2배 식초에서 총 24종의 유리아미노산이 확인되었고, 유리아미노산과 필수아미노산의 함량이 가장 높은 것으로 확인되었다. 총 페놀 및 총 플라보노이드 함량은 사과농축액을 원료로 한 2배 식초에서 가장 높게 확인되었고, 이는 DPPH 및 ABTS 라디칼 소거활성에도 영향을 주어 유사한 결과를 나타내었다. 고산도 식초의 품질은 사용된 원료와 제조방법에 영향을 받았으며, 사과를 이용한 2배 식초는 가장 우수한 항산화활성을 나타내었다.

• 한국식품과학회지
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• 제44권6호
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• pp.699-703
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• 2012

시판 사과식초의 총산 함량에 따른 이화학적 품질특성을 비교하였다. 사과식초 산도의 증가에 따라 pH는 감소하였고, 총 산도는 증가하였다. 환원당 함량 및 갈색도는 산도의 증가에 따라 감소하는 경향을 나타내었는데, 이는 제조과정의 차이가 최종 제품에 영향을 미친 것으로 사료되었다. 유리당은 산도에 관계없이 fructose의 함량이 가장 높게 나타났고, glucose의 함량이 그 뒤를 이었다. 총 유리당 함량은 저산도, 2배 산도, 일반산도, 3배 산도식초의 순으로 확인되었다. 유기산의 경우 acetic acid와 malic acid가 주로 확인되었다. 원료 중 과즙의 함량이 가장 높은 저산도 식초에서는 oxalic acid, citric acid, tartaric acid 등이 확인되었고, 구연산이 사용된 3배 산도 식초의 경우 citric acid 함량이 가장 높게 확인되었다. 총 페놀 및 총 플라보노이드 함량은 저산도 식초에서 가장 높게 측정되어 사과과즙 함량의 차이가 최종 제품의 함량에 어느 정도 영향을 미친 것으로 추측되었다. 시료의 DPPH 및 ABTS radical 소거능은 항산화물질의 함량이 높은 저산도 식초에서 가장 높게 확인되었다.

• Bulletin of the Korean Chemical Society
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• 제22권12호
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• pp.1303-1308
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• 2001

A series of catalysts, NiSO4/TiO2, for ethylene dimerization was prepared by the impregnation method using aqueous solution of nickel sulfate. On the basis of the results obtained from X-ray diffraction, the addition of NiSO4 shifted the transition of TiO2 from the anatase to the rutile phase toward higher temperatures due to the interaction between NiSO4 and TiO2. Nickel sulfate supported on titania was found to be very active even at room temperature. The high catalytic activity of NiSO4/TiO2 closely correlated with the increase of acidity and acid strength due to the addition of NiSO4. It is suggested that the active sites responsible for ethylene dimerization consist of low valent nickel, Ni+, with an acid.

• 한국식품영양학회지
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• 제26권1호
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• pp.51-59
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• 2013

This study aims to understand college students customer's preference and the difference of coffee grade by comparing the result of Q-grader, who was trained professionally and received certification for a sensory evaluation of coffee grade. The results of the chemical analysis of raw coffee and coffee berry show that those of specialty grade had slightly higher, but not significant, water content. Further, the pH of specialty grade coffee was high in coffee beans and after roasting, the commercial grade became high. There was no significant difference between the specialty degree and commercial degree in color before and after roasting. In this study, the panels for the sensory evaluation included 24 university students. The preference of evaluation items of sensory evaluation consist of aroma, acidity, bitterness, astringency, aftertaste, and overall satisfaction. Items for the strength evaluation consist of aroma, acidity and bitterness. The sensory evaluation was expressed by applying a 5 point Likert scale (1: extremely low~5: extremely high). In the sensory evaluation, it was evaluated that specialty grade coffee had strong acidity and commercial grade coffee was strongly bitter. The result of the sensory evaluation shows that female students are sensitive to coffee taste. In the analysis of frequent visit to coffee shop, the not-frequently-use-group rated that specialty grade coffee with higher overall satisfaction than commercial grade coffee in factors such as aroma and acidity. The group which did not prefer Americano coffee rated that specialty grade was higher than commercial grade in all factors except aroma, of which the result is similar to the cupping test.

• Carbon letters
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• 제9권1호
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• pp.8-16
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• 2008

Oxidized activated carbons were prepared by reacting steam-activated carbon developed from pecan shells with nitric acid of varying strength (15, 30, 45 and 60%). The textural properties and the chemistry of the surface of the non-oxidized and of the oxidized carbons were determined from nitrogen adsorption and base neutralization capacities. The uptake of Pb(II) and Cd(II) from aqueous solution by these carbons was determined by kinetic and equilibrium experiments as well as by the column method. Treatment with nitric acid brought about drastic decrease in surface area and remarkable increase in the pore size of the carbon with these changes depending on the strength of nitric acid. Nitric acid increased the surface acidity by developing new surface oxygen functional groups of acidic nature. $HNO_3$-oxidized carbons exhibited high adsorption capacities for Pb(II) and Cd(II). The adsorption of these ions increased with the decrease of the surface pH of the carbon and with the increase of the solution pH from 2.5 to 6 and 7. The amount adsorbed from lead and cadmium was also related to the amount of surface acidity, the pH of the point of zero charge and on some metal ion parameters. Cadmium and lead uptake by the investigated carbons followed pseudo-second order model and the equilibrium sorption data fitted Langmuir adsorption model.

• Bulletin of the Korean Chemical Society
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• 제27권10호
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• pp.1623-1632
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• 2006

NiO supported on zirconia modified with $MoO_3$ for acid catalysis was prepared by drying powdered $Ni(OH)_2-Zr(OH)_4$ with ammonium heptamolybdate aqueous solution, followed by calcining in air at high temperature. The characterization of prepared catalysts was performed using FTIR, Raman, XRD, and DSC. $MoO_3$ equal to or less than 15 wt% was dispersed on the surface of catalyst as two-dimensional polymolybdate or monomolybdate, while for $MoO_3$ above 15 wt%, crystalline orthorhombic phase of $MoO_3$ was formed, showing that the critical dispersion capacity of $MoO_3$ on the surface of catalyst is 0.18 g/g NiO-$ZrO_2$ on the basis of XRD analysis. Acidity and catalytic activities for acid catalysis increased with the amount of dispersed $MoO_3$. The high acid strength and acidity was responsible for the Mo=O bond nature of the complex formed by the interaction between $MoO_3$ and $ZrO_2$. The catalytic activity for acid catalysis was correlated with the acidity of the catalysts measured by the ammonia chemisorption method.

• 한국식품과학회지
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• 제31권2호
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• pp.410-415
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• 1999

고전장 펄스를 사용하여 전통 약주의 살균에 미치는 영향을 조사하였다. 약주 미생물 살균에 필요한 최소 임계전기장의 세기(Ec)는 총균의 경우 16.0 kV/cm이었다. 임계전기장의 세기이상의 전기장의 세기에서 미생물은 세포막이 붕괴되어 사멸하였으며 전기장의 세기가 증가할수록 약주 미생물의 살균효과는 증가하는 것으로 나타났다. 처리시간이 증가함에 따라 살균효과가 증가하는 것으로 나타났으며 처리시간 $2000{\mu}s$이상에서 $6000{\mu}s$까지 더 많은 시간을 처리하였을 경우에는 살균효과가 증가하지 않았다. 저장 실험 기간동안 대조구의 pH는 저장기간에 따라 감소하였으며 산도는 증가하였다. 대조구의 산도가 $4^{\circ}C$에서 저장했을 때 보다 $30^{\circ}C$에서 저장하였을 경우 더욱 빠른 변화를 나타낸 반면 PEF 처리구는 산도의 감소가 없었다. 미생물의 경우 대조구에서는 저장기간에 따라 미생물수가 증가하였으나 PEF 처리한 시료는 저장 9주 동안 미생물의 생육을 전혀 보이지 않았다.

• Bulletin of the Korean Chemical Society
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• 제16권6호
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• pp.507-511
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• 1995

Catalytic chlorination of chlorobenzene was studied in vapor phase using various solid-acid catalysts such as silica-alumina, alumina, zeolite and a modified clay prepared by impregnating bentonite with ferric chloride. The conversions of both chlorine gas and chlorobenzene showed high over silica-alumina, alumina and modified clay catalysts. However relatively large amounts of polychlorinated benzene derivatives were also observed. The active species of catalytic activity in chlorination of chlorobenzene in vapor phase were proved to be as Lewis acid sites by in-situ IR experiments. The strength of Lewis acid sites which were effective for the vapor-phase chlorination seemed to be having Hammett acidity Ho >-3.0. The selectivity to dichlorobenzenes was proved to be high over the zeolite catalyst due to their shape-selective properties. p-Dichlorobenzene or dichlorobenzene selectivities were improved more or less by changing the reaction conditions.

• Bulletin of the Korean Chemical Society
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• 제27권6호
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• pp.821-829
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• 2006

A series of catalysts, $NiO/La_2O_3-ZrO_2/WO_3$, for acid catalysis was prepared by the precipitation and impregnation methods. For the $NiO/La_2O_3-ZrO_2/WO_3$ samples, no diffraction lines of nickel oxide were observed, indicating good dispersion of nickel oxide on the catalyst surface. The catalyst was amorphous to X-ray diffraction up to 300 ${^{\circ}C}$ of calcination temperature, but the tetragonal phase of $ZrO_2$ and monoclinic phase of $WO_3$ by the calcination temperatures from 400 ${^{\circ}C}$ to 700 ${^{\circ}C}$ were observed. The role of $La_2O_3$ in the catalyst was to form a thermally stable solid solution with zirconia and consequently to give high surface area and acidity. The high acid strength and high acidity were responsible for the W=O bond nature of complex formed by the modification of $ZrO_2$ with $WO_3$. For 2-propanol dehydration the catalyst calcined at 400 ${^{\circ}C}$ exhibited the highest catalytic activity, while for cumene dealkylation the catalyst calcined at 600 ${^{\circ}C}$ showed the highest catalytic activity. 25-$NiO/5-La_2O_3-ZrO_2/15-WO_3$ exhibited maximum catalytic activities for two reactions due to the effects of $WO_3$ modifying and $La_2O_3$ doping.

• 한국식품영양학회지
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• 제25권4호
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• pp.1033-1038
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• 2012

This study was done to provide basic information about the storage and distribution of specialty grade coffee of which the market will be expanded through customer sensory evaluation according to the storage period of specialty grade coffee by the SCAA classified method with consideration to defective beans and scent. The specialty grade coffee sample of this study was extracted on day 1, day 14, and day 28. The water content showed a significant reduction on the 28th storage day and there was no pH change according to the storage period. Color degree was brightened according to the preservation period before and after grinding but there was no significant difference. The panels for sensory evaluation considered of 24 university. The sensory evaluation consist of aroma, bitterness, and astringency, acidity, aftertaste, overall satisfaction, and items for strength estimation consist of aroma, acidity and bitterness. The sensory evaluation was expressed by applying a 5 point Likert scale. The results showed that as the storage period increased so too did the aroma and the strength of bitterness. Preference was the highest on day 1 in every items except aroma and astrigency. However on day 14 and day 28, most of the sensory evaluation became low and then became high, which was inconsistent. Male students were not consistent in their evaluation according to the preservation period, but female students rated aroma and bitterness the lowest on preservation period day 1 and they prefer after a storage period of 1 day in regards to the entire degree of satisfaction including sour test. astrigency and aftertaste. The analysis of visiting frequency for coffee shops used demonstrated that the longer the preservation period, the lower the preference but was not significant in the case of involving a little frequency group. The group that did not like Americano coffee evaluated that the longer the preservation period, the lower the preference based on Americano coffee preference analysis. There was no consistency between the storage period day 14 and day 28 in strength and preference, but preference for storage period day 1 was high in every group, which means that the quality of coffee is affected by the preservation period.