• The Korean Journal of Food And Nutrition
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• v.26 no.1
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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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.6
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• pp.925-931
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• 1995

Volatile compounds in Cheddar, Emmentaler, Parmesan and Roquefort cheese and cheese aroma were concentrated using a microsteam distillation-extraction apparatus and those compounds were analyzed with GC. The lipase-treated cheese aroma concentrates showed significantly higher level of short-chain free fatty acids than natural ripened cheese. The sensory properties of rancidity was high in Emmemtaler and Parmesan. Acidity and fruitness were shown high score in Roquefort. Correlation of free fatty acids and cheese flavor 'sharpness, rancidity and soapy' appear to be related(r=0.8239, 0.8918 and 0.7503), respectively. Methyl ketones, the most striking flavor components of Roquefort cheese showed high amounts in the series 2-heptanone > 2-nonanone > 2-pentanone > 2-undecanone. And the intensity of the Roquefort taste sensation 'acidity and fruitness' is linearly correlated with the methyl ketone concentrations(r=0.9284, r=0.9659).

• Journal of the Korean institute of surface engineering
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• v.43 no.6
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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.

• Journal of Environmental Science International
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• v.4 no.1
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• pp.53-62
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• 1995

To collect and evaluate an aerosol acidity ($H^+$) in ambient air, the cyclone/annular denuder/filter pack sampling system (ADS) was used. Aerosol acidity was collected in Chicago using the ADS for 81 12-hr samples divided in spring/summer/fall 1990 and winter 1991. This study illustrated that the ADS was suitable for measuring aerosol acidity. The $10^{-5}N$ $HCIO_4$ extraction solution for pH determination provided more reliable scale than $10^{-4}N$ HClO4. NH3 should be removed prior to particle collection to accurately measure $H^+$ concentration on the filter. There was seasonal variation in aerosol acidity concertrations. Aerosols were more acidic in the summer. High correlations between $SO_4^{2+} and$NH_4^+$, and between TEX>$SO_4^{2+}$H^+$ were observed during the entire sampling period.

• Journal of Korean Society for Atmospheric Environment
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• v.2 no.3
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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.

• The Korean Journal of Food And Nutrition
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• v.20 no.4
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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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• v.18 no.3
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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.

• Microbiology and Biotechnology Letters
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• v.21 no.5
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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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• s.20
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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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.6
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• pp.877-883
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• 2014

This study investigated the manufacturing conditions of apple vinegar with high acetic acid content following fermentation according to alcohol concentration without any nutrients. We compared and analyzed the quality characteristics of high acetic acid fermentation by varying the initial alcohol content (6%, 7%, 8%, and 9%). In the results, it was possible to manufacture high acetic acid vinegar with 12% titratable acidity and an alcohol content of 6% and 7%. Lower initial alcohol content was associated with higher yield due to a shorter lag phase. For quality characteristics of the high acetic acid apple vinegar, pH was 2.91~3.20, titratable acidity was 12.0%, and organic acid consisted of acetic acid, malic acid, critic acid and oxalic acids. Based on the results, high acetic acid apple vinegar was produced using a two stage fermentation process after alcohol fermentation but the further research is needed to reduce the time of fermentation in fed-batch culture for industrial use.