• Applied Chemistry for Engineering
• /
• v.5 no.2
• /
• pp.223-229
• /
• 1994

The effect of agitation speed on mass transfer coefficient in the extraction of citric acid from mixed aqueous solutions of citric and acetic acid with n-butylacetate solutions of di-isotridecylamine(DITDA) and 50% mixture of tri-n-octyl and try-n-hexyl phosphine oxide(MOHPO), were studied in batch extractor. Experimental results showed that the degree of extraction was higher with increasing agitation speed, and was best at 200rpm and 30 minutes in batch extractor. The higher degree of extraction was obtained in mixed solution of citric-acetic acid by using DITDA than MOHPO as an carrier. Mass transfer coefficient was proportional to the degree of extraction, and $K_r=1.254{\times}10^{-3}Re^{0.536}$ was found for she extraction of citric acid by DITDA.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2004.02a
• /
• pp.83-95
• /
• 2004

The removal efficiency of several washing agents on the $Cs^+$ ion was investigated. Leaching of $Cs^+$ ion from the soil surface by washing agents is affected by the exchange capability of the washing solution. Reuse tests of the effective soil washing agents such as $BaCl_2$, NaOH, citric acid＋ $HNO_3$ and oxalic acid were performed. NaOH, citric acid ＋ $HNO_3$ and oxalic acid solutions can be reused after passing through the ion exchange column. Among the tested solutions, both of citric acid＋ $HNO_3$ and oxalic acid were effective for the decontamination of TRIGA research reactor soil. The radioactivity of soils can be reduced to a release level by the successive application.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.13 no.1
• /
• pp.29-35
• /
• 1987

Purely synthesized L-ascorbic acid 2 phosphate Mg salt (1 AsA PMg) improved the weak point of ascorbic acid which is easily decomposed in water solution. This compound is hydrolyzed with phosphatase of skin to corresponding ascorbic acid giving Vitamine C activities. The buffer solution of potassium acetate 0.5% and citric acid 0.005% and the sodium sulfite respectively showed good stabilizing effect of the AsA PMg solution. Compared to the other ascorbic acid derivatives the good solubility of AsA PMg gives broad application to cosmetic field.

• Journal of the Korean Home Economics Association
• /
• v.32 no.5
• /
• pp.143-152
• /
• 1994

To investigate the changes of taste perception by aging, sixty one healthy elderly people and sixty five young adults were participated in the study. Most preferred levels of salt sour and sweet taste were chosen in bean sprout soup radish salad and yaksing respectively. Threshold levels of each taste were also chosen in NaCl solution for salt taste in citric acid solution for sour taste and in sucrose solution for salt taste, in citric acid solution for sour taste and in sucrose solution for sweet taste. The results are as follow: 1.Most preferred salt concentration in bean sprout soup was significantly higher in the elderly than in the young adults(p$\leq$0.001). There was no difference in sour taste preference of radish salad in both age groups. Most preferred sweetness in yacksig was significantly higher in both elderly men and women(p$\leq$0.001) 2. Threshold levels of salt and sweet taste were significantly higher in the elderly (p$\leq$0.001) However there was no difference in threshold level of sour taste in both age groups.

• Korean Journal of Food Science and Technology
• /
• v.38 no.1
• /
• pp.35-41
• /
• 2006

Possible application of hurdle technology extention of shelf-life of fresh-cut apples was investigated by evaluating various hurdle factors known to be effective microbial growth inhibitors and their synergistic effects. Fresh-cut apples treated with chitooligosaccharide or grapefruit seed extract (GSE) showed higher microbial counts than those treated with distilled water during latter half of storage period, and at high concentrations. Citric and malic acids showed similar results, although microbial counts of fresh-cut apples treated with 0.75% or higher concentration of citric acid increased at 4 days of storage at $18^{\circ}C$, indicating malic acid is more effective than all hurdles tested for controlling microbial growth. Using ascorbic acid and calcium chloride as additional hurdles to control browning and softening, minimum and maximum compositions of dipping solution were: 0.25 : 0.5 : 0.25% and 0.75 : 1.0 : 0.75% malic acid: ascorbic acid: calcium chloride, respectively.

• Corrosion Science and Technology
• /
• v.14 no.4
• /
• pp.166-171
• /
• 2015

Knowledge of how metal releases from the stainless steels used in food processing applications and cooking utensils is essential within the framework of human health risk assessment. A new European standard test protocol for testing metal release in food contact materials made from metals and alloys has recently been published by the Council of Europe. The major difference from earlier test protocols is the use of citric acid as the worst-case food simulant. The objectives of this study were to assess the effect of citric acid at acidic, neutral, and alkaline solution pH on the extent of metal release for stainless steel grades AISI 304 and 316, commonly used as food contact materials. Both grades released lower amounts of metals than the specific release limits when they were tested according to test guidelines. The released amounts of metals were assessed by means of graphite furnace atomic absorption spectroscopy, and changes in the outermost surface composition were determined using X-ray photoelectron spectroscopy. The results demonstrate that both the pH and the complexation capacity of the solutions affected the extent of metal release from stainless steel and are discussed from a mechanistic perspective. The outermost surface oxide was significantly enriched in chromium upon exposure to citric acid, indicating rapid passivation by the acid. This study elucidates the effect of several possible mechanisms, including complex ion- and ligand-induced metal release, that govern the process of metal release from stainless steel under passive conditions in solutions that contain citric acid.

• Korean Journal of Food Science and Technology
• /
• v.33 no.1
• /
• pp.149-152
• /
• 2001

Extraction characteristics of anthocyanin pigment from red flower cabbage(Brassica oleracea L. var. acephala) as a new source of natural food colorant were investigated. The pigment extracted from red flower cabbage showed the characteristic bathochromic shift of the maximum wavelength of light absorption(${\lambda}_{max}$) as pH of the solution changed from pH 1 to 12. As the concentration of citric acid in the extraction solvent increased, extraction rate and total optical density(TOD) of the extract increased. Maximum TOD was obtained by using the extracting solvent including $0.8{\sim}1.0%$ citric acid and stable pigment solution was obtained by using the extracting solvent including $10{\sim}20%$ ethanol in distilled water. As a result, 10% ethanolic solution with 0.8% citric acid was decided as the optimum extraction solvent for the anthocyanin pigment from red flower cabbage. Within the experimental ranges, the extraction rate increased and therefore extraction time decreased as the extraction temperature increased. The times to reach a certain value of TOD i.e., 2.1 were 24, 8, 4 and 2 hours at extraction temperature of 5, 20, 40 and $60^{\circ}C$, respectively.

• Journal of Microbiology and Biotechnology
• /
• v.3 no.2
• /
• pp.129-133
• /
• 1993

The effect of different compositions of organic acids on the flavor profile of 10% sugar solution was investigated by the response surface methodology, and the results were used to evaluate the flavor characteristics of lactic acid fermented cereal beverages. A mixture of extruded rice flour (10%) and soymilk (7.8% dry matter) was fermented with Leuconostoc mesenteroides (Sikhae). Depending on the substrate pretreatments, for example, the malt or amylase digestion and the proteolytic enzyme hydrolysis, the sugar and organic acid composition of the product varied. The organic acid composition of the fermented beverages was in the ranges of 0.44-0.55% lactic acid, 0.05-0.09% acetic acid and 0.07-0.09% citric acid, while that of commercial apple juice was 1.59% malic acid and 0.49% acetic acid. The flavor profiles of fermented beverages added with 10% sucrose were compared to those of apple juice and a model mixture containing 0.48% citric acid, 0.39% lactic acid and 0.12% acetic acid in 10% sugar solution. The QDA diagram of fermented beverages approached to that of apple juice, when the substrate was digested by amylase but not by protease.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.32 no.7
• /
• pp.960-964
• /
• 2003

Effects of pH, sugars, organic acids, and metal ions on the stability of anthocyanin pigments extracted from mulberry (Morus alba L) fruit were studied. The pH had marked influences on the color of the anthocyanine pigment: i.e. the lower pH of the anthocyanin solution was, the more stable and intense of the pigment was. Among the sugars, sucrose was the most deleterious followed by fructose, glucose and maltose. Among the organic acids, maleic acid was found to be the most effective in stabilizing the pigment followed by acetic acid, citric acid and tartaric acid. Most metal ions except C $u^{+2}$ and F $e^{+3}$ were found to be effective in stabilizing the pigment.

• Restorative Dentistry and Endodontics
• /
• v.23 no.1
• /
• pp.379-390
• /
• 1998

In endodontic treatment, calcium hydroxide has been used as intracanal medicament. Although calcium hydroxide should be removed thoroughly before permanent root canal filling, no effective method for its removal has been reported. Because of irregularity of root canal walls, root curvatures and anatomic variations, it is insufficient to remove calcium hydroxide from the canal wall only by mechanical instrumentation Considering the chemical effects of irrigants on calcium hydroxide, $Ca^{++}$ dissolving effect from two calcium hydroxide products is investigated, using dis- tilled water, NaOCl, citric acid and EDTA. Vitapex$^{(R)}$ 0.1g and calcium hydroxide 0.03g were dissolved in distilled water, 5% NaOCl, 50% citric acid and 17% EDTA respectively, at 1, 3, 5, 10min. time interval. The solution was filtered using filter paper(pore size $5{\mu}m$) and $Ca^{++}$ concentration was determined by ion chromatography. The result were as follows : 1. Distilled water, NaOCl, citric acid and EDTA abstracted more $Ca^{++}$ from calcium hydroxide than Vitapex$^{(R)}$ except NaOCl 1, 5, 10 time interval. 2. EDTA and citric acid abstracted more $Ca^{++}$ from Vitapex$^{(R)}$ and calcium hydroxide than distilled water or NaOCl. The overall result support the view that water-based calcium hydroxide product is easily removed than oil-based calcium hydroxide product and EDTA, citric acid are more effective in $Ca^{++}$ elution than NaOCl or distilled water.