• 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.

• 한국식품영양과학회지
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• 제24권6호
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• pp.925-931
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• 1995

Cheddar, Emmentaler, Parmesan 그리고 Roquefort 치즈 등 자연 숙성 치즈와 지방 분해효소를 첨가하여 발효시킨 뒤 치즈향 농축물의 휘발성 향기 성분을 GC 및 관능적 분석을 통하여 비교하였다. 저급지방산이 그 특유의 향미를 나타내는데 가장 큰 영향을 미치는 성분으로 알려진 Parmesan 치즈향 농축물과 향미와 주성분으로 알려진 Cheddar 치즈향 농축물은 그 함량이 다른 시료 보다 10배 이상 높게 나타났따. 또한 메틸 케톤이 그 독특한 풍미의 결정적 온도가 되는 Roquefort 치즈의 경우는 제조시 lipase 및 P. roqueforti의 첨가로 메틸 케톤의 생성을 촉진시켜준 Roquefort 향 농축물의 함량이 월등히 높았다. 관능적 특성 차이를 비교한 결과 Cheddar, Emmentaler 그리고 Parmesan 치즈향 농축물이 sharpness, rancidity, soapy의 강도가 자연치즈 보다 유의성 있게 높았다. 반면, Roquefort 향 농축물에 있어서는 acidity, fruitness 등이 유의성 있게 높게 나타났다. GC profile과 관능적 특성과의 상관관계는 free fatty acid와 sharpness, rancidity, soap는 각각 0.8239, 0.8918, 0.7503 그리고 methyl ketone과 acidity, fruitness는 각기 0.9284, 09659의 높은 상관계수를 보였다.

• 한국표면공학회지
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• 제43권6호
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• pp.297-303
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• 2010

The effect of solution acidity and organic additives, polyethylene glycol (PEG), on the trivalent chromium electroplating was systematically investigated in the view point of electroreduction of trivalent chromium ions and solution stability. It was found that solution acidity controlled at pH 2.5 showed the widest current range for bright electrodeposits in the presence of PEG additives, which reduced the local current intensification at high current densities. Through complex interaction between PEG additives and hydrogen ion, that is, solution acidity, electrode potential was moved in the negative direction in the bulk solution, while it shifted in the positive when electric potential was scanned. In conjunction with electrochemical quartz crystal microbalance (EQCM), it was found that PEG additives had a role in promoting the electron transfer to trivalent chromium ion complexes in bulk solution and their adsorption at the electrode surface as well as interfering with hydrogen ion reduction process below pH 2.5. The PEG additives developed the nodular morphology during electroreduction of trivalent chromium ions with the increase of solution acidity and enhanced its current efficiency by maintaining the consumption of complexant, formic acid, at low speed.

• 한국환경과학회지
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• 제4권1호
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• pp.53-62
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• 1995

대기중의 산성도($H^+$)를 측정하기 위하여 디누더 시스템(Annula Denuder System)을 이용하였다. 산성도 측정은 1990년 4월 부터 1001년 3월 까지 미국 시카고에서 81개 샘플을 12시간 동안 낮과 밤을 구분하여 측정하였다. 본 연구를 통하여 대기중의 산성도 측정은 디누더 시스템을 이용하면 보다 정확한 결과를 얻을 수 있을음 알 수 있었다. 여과지에 포집된 산성도($H^+$)를 추출해 낼때 사용하는 $HCIO_4$용액은 $10^{-5}N$의 농도를 사용하는 것이 $10^{-4}N$의 농도보다 더 정확한 결과를 얻을 수 있다. 보다 정확한 산성도를 측정하기 위해서는 에어로졸이 여과지에 포집되기 전에 가스 상태의 $NH_3$가 먼저 제거되어야 한다. 산성도는 계절에 따라 변하였고 여름에 가장 높은 농도를 나타냈다. $SO_4^{2+} 와 $NH_4^+$, 그리고 $SO_4^{2+}와 $H^+$의 상관관계는 높은 것으로 나타났다.

• 한국대기환경학회지
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• 제2권3호
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• pp.45-51
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• 1986

The simple and precise model for the estimation of rain acidity from the ambient air quality was developed using the theory of wet scrubber and the chemical equilibria of $SO_2, CO_2, and H_2O$ system. From the measured mixing height, and from the developed relationship between NTU (=number of transfer units) and the concentration of $SO_2$(aq) in rain drops, the HTU (= height equivalent to one transfer unit, i.e. mass transfer resistance) was estimated, and validated with the field-measured data. In Seoul, Korea where the effect of $SO_2$ on rainfall acidity is as high as 84% and the average mixing height is 1 km, the average HTU of $SO_2$ system was found to be 191.5m. The important parameters affecting HTU were identified as rainfall intensity and initial ambient concentration of $SO_2$, and their effects on the value of overall volumetric mass transfer coefficient were quantified.

• 한국식품영양학회지
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• 제20권4호
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• pp.421-426
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• 2007

This study was carried out to investigate the properties of Kimchi made with potato as compared to Kimchi made with radish. The pH, acidity, hardness, and number of lactic acid bacteria were examined as properties of the Kimchi to determine the suitability of adding the potato and with focus on the possible duration of storage. First in the case of pH, the storage duration at pH $4.2{\sim}4.3$, which is the state for optimal tasting Kimchi, was approximately 10days in the control group, while that of the experimental group was 10 to 16 days, and thus, longer than the control. Second in the case of acidity, representing the maturity of Kimchi, we examined the time it took to reach 0.6% acidity, in which the experimental group took more longer time than the control. Although the experimental group was slower to mature than the control, the period for keeping at the proper pH was longer than that of the control group. Thirdly, in the case of hardness, which relates to softening, the experimental group had remarkably high values. This suggests that the Kimchi in the experimental group had a more rigid texture and more difficultly softening than the control group. Lastly in the case of the number of lactic acid bacteria, which closely relates to the process of fermentation, there were no significant differences. In conclusion, these results indicate that adding potato to Kimchi can extend its storage period.

• Food Science and Biotechnology
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• 제18권3호
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• pp.636-640
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• 2009

The effect of post-cut vanillin treatment at high concentrations on changes of quality and microorganism in fresh-cut apples was studied. Apples (Malus domestica Borkh. cv. Fuji) were sliced, treated by dipping in different vanillin solution, 0, 40, 80, and 120 mM, packed in polyethylene bag, and then stored for up to 3 weeks at $4^{\circ}C$. Changes in total aerobic bacteria, yeast and molds, browning, soluble solids, and titratable acidity during storage were investigated. Growth of total aerobic bacteria throughout storage was strongly inhibited by vanillin regardless of treatment concentrations. Growth of yeast and molds was inhibited by vanillin of all concentrations until 2 weeks of storage. Levels of browning index, soluble solids, and titratable acidity were not significant difference among the treatment conditions until 2 weeks of storage. However, when stored for 3 weeks, browning index increased more at 80 or 120 mM vanillin, while soluble solids and titratable acidity more be decreased by 120 mM vanillin as compared with other treatment conditions. These results show that the usage of vanillin in processing of fresh-cut apples had a limitation for maintaining quality.

• 한국미생물·생명공학회지
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• 제21권5호
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• pp.511-512
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• 1993

The production of vinegar containing high acetic acid concentration was carried in a single stage fed-batch culture. The initial and residual ethanol concentration were 50.0g/l and 5.0g/l, respectively, and the ethanol concentration was maintained from 5.0g/l to 10.0g/l during fedbatch culture. The fermentation temperature was decreased by 1C for every increase of 2.0% in acidity. The maximum productivity was 2.53g/l-hr and the acidity was 16.08% after 40 hours of acetic acid fermentation.

• 보존과학연구
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• 통권20호
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• pp.49-64
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• 1999

According to damage of papers by the chemical cause, papers become to acidify. Among the 3 kinds of method measuring the acidity of paper, one was nondestructive method measuring the surface of the paper by flat type electrode and the others were destructive methods measuring directly by cold water extract method and hot water extract method. In case of the cellulolytic cultural properties, the latter methods were not applied because those methods must bedissociated papers. To measure the paper acidity nondestructively, we investigated the correlation of the nondestructive method and the destructive methods. The conclusions are as follows. 1) In the relationship of the cold water extract method and the hot water extract method, It was indicated that the pH measured by the hot water extract method was high quality printing paper 0.08, rough printing paper 0.13, and Korean paper 0.29 higher than that by the cold water extract method.2) In the relationship of the cold water extract method and the surface measurement method, It showed that the pH value measured by the cold water extract method was high quality printing paper 1.86, rough printing paper 0.80,and Korean paper 0.58 higher than value that by the surface measurement.3) In the relationship of the hot water extract method and the surface measurement method, It showed that the pH value measured by the hot ABSTRACT water extract method was high quality printing paper 1.78, rough printing paper 0.66, and Korean paper 0.29 higher than that by the surface measurement. From the above-mentioned results, the pH value measured by the surface measurement was need to high about 1.78∼1.86 in high quality printing paper, 0.66-0.80 in rough printing paper, and 0.29∼0.58 in Korean paper and the surface measurement with flat type electrode was very available to measure the acidity of Korean papers actually.

• 한국식품영양과학회지
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• 제43권6호
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• pp.877-883
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• 2014

본 연구에서는 사과 농축액을 이용하여 일체의 영양원을 첨가하지 않고 알코올 및 초산 발효과정으로 고산도 식초의 제조 조건을 조사하였다. 초기 알코올 함량(6, 7, 8 및 9%)을 달리하여 고산도 초산 발효액의 품질특성을 비교 분석하였다. 그 결과 알코올 함량 6% 및 7%에서 적정산도 12%의 고산도 식초 제조가 가능하였으며, 초기 알코올 함량이 낮을수록 유도기가 단축되어 수율이 높은 경향이었다. 상기 고산도 사과식초의 품질특성은 pH 2.91~3.20이고 적정산도 12.0%이며 유기산은 acetic, malic, citric 및 oxalic acid가 검출되었다. 이상의 결과 사과 농축액을 이용하여 알코올 발효 후 2단계 발효과정으로 고산도 사과식초 제조가 가능하였으나 산업적으로 활용하기 위해서는 유가식 첨가에 의한 발효기간 단축에 관한 연구가 요구되었다.