• Journal of Soil and Groundwater Environment
• /
• v.21 no.6
• /
• pp.146-155
• /
• 2016

The field feasibility tests for a phytoextraction process were performed to identify the effect of citric acid as a chelate on the uranium (U) transfer into the plant for the naturally U contaminated soil in Duckpyeongri, Korea. For the feasibility tests, lettuce and Chinese cabbage were cultivated for 49 days on four testing grounds ($1m{\times}1m{\times}0.5m$ in each) in 2016. The citric acid solution was added to two testing grounds (one for lettuce and the other for Chinese cabbage) increasing the U transfer in two crop plants and their results were compared to those without the citric acid solution. When without the citric acid solution, the U concentration of plant after the cultivation was low (< $45{\mu}g/kg$ for leaves and < $450{\mu}g/kg$ for roots). However, with the addition of 50 mM citric acid solution, the U concentration of lettuce leaves and roots increased by 24 times and 1.8 times, and the U concentration of Chinese cabbage leaves and roots increased by 86.7 times and 5.4 times. The absolute accumulated U amount (${\mu}g$) in lettuce and Chinese cabbage also increased by 8.7 times and 50 times, compared to those without citric acid solution. Less than 8% of the U amount of exchangeable/carbonate phases was removed by using the lettuce and Chinese cabbage when the citric acid solution was not applied. However 52% and 66% of the U amount in exchangeable/carbonate phases were removed by the lettuce and the Chinese cabbage when the citric acid solution was added. The effect of the citric acid on the U transfer capability into the plants was quantitatively investigated by the field feasibility test, suggesting that U existing as exchangeable/carbonate phase in soil can be successfully removed by the phytoextraction process using Chinese cabbage with citric acid.

• Proceedings of the IEEK Conference
• /
• 2001.06b
• /
• pp.33-36
• /
• 2001

In this paper, we have studied the characteristics of wet etching using citric acid based wet etchant. We have used the citric acid / hydrogen peroxide solution, citric acid / hydrogen peroxide / D.I. water solution. From our experimental result, a volumetric 1：3 ratio of citric acid and hydrogen peroxide and 1 ： 3 ： 1 ratio of citric acid, hydrogen peroxide, and D.I. water is shown to be a better wet etchant of PHEMT's system.

• Journal of Applied Biological Chemistry
• /
• v.66
• /
• pp.90-97
• /
• 2023

The effect of citric acid on rice starch gelatinization and low-temperature (4 ℃) storage was studied in order to produce rice cake with a lower retrogradation rate. A citric acid solution in the ratio of 0, 0.5, 1.0, and 1.5% (w/w) of the water used during production was utilized. The gelatinization properties, gel strength, thermal properties, and texture analysis were evaluated to determine the retrogradation rate. The result showed that acid hydrolysis occurred in samples treated with citric acid. Thus, increasing citric acid decreased gelatinization temperature (58.63±1.98 to 45.84±1.24 ℃). The moduli of elasticity increased with increasing citric acid concentration, indicating an increased gel strength. Thermal analysis of starch showed that the onset, peak, and conclusion temperatures of retrogradation were increased significantly with the storage period and decreased with citric acid concentration. After 72 h of low-temperature storage (4 ℃), the retrogradation rate was lowest in the rice cake with 1.5% citric acid solution, with an increased ratio of 12.01 to 13.60% compared to the control sample, with a ratio of 12.99 to 43.54%. This shows a high retrogradation rate in the control sample. Additionally, sensory properties and retrogradation ratio suggest that the addition of 1.0% citric acid solution during rice cake production is efficient in retarding the retrogradation without an adverse effect on the rice cake modeling and acceptance.

• Food Science and Biotechnology
• /
• v.17 no.4
• /
• pp.878-882
• /
• 2008

The efficacy of citric acid-aqueous chlorine dioxide ($ClO_2$) treatment of radish seeds artificially contaminated with Escherichia coli was studied. Radish seeds were inoculated with E. coli. Following inoculation, samples were stored at $4^{\circ}C$ and soaked in citric acid or aqueous $ClO_2$ for 10 min. The treatment of radish seeds using 200 ppm aqueous $ClO_2$ solution caused a 1.5 log CFU/g reduction in the population of E. coli. Compared to the aqueous $ClO_2$ treatment, soaking radish seeds in 2.0% citric acid solution for 10 min was more effective in reducing E. coli populations on radish seeds. The efficacy of spray application of chlorine (100 ppm) or 0.5% citric acid to eliminate E. coli during the germination and growth of radish was investigated. Radish seed inoculated with E. coli was treated for the duration of the growth period. Although it resulted in a decrease in the E. coli population, the spray application of 100 ppm chlorine during the growth period was not significantly effective. In contrast, the combined treatment of seeds using 200 ppm aqueous $ClO_2$ and treatment of sprouts with 0.5% citric acid solution during sprout growth was hardly effective in eliminating E. coli.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.28 no.6
• /
• pp.1269-1274
• /
• 1999

Four dimensional response surface methodology was applied to determine the optimum conditions on organoleptic properties to develop red pepper jam into Korean type jam. The organoleptic color of red pepper jam showed maximum score of 8.08 in 14.24g pectin, 256.2g sucrose and 8.31ml citric acid(50% citric acid solution). The organoleptic taste of red pepper jam showed maximum score of 6.77 in 14.23g pectin, 202.1g sucrose and 8.19ml citric acid. Optimum conditions on the organoleptic mouth feel of red pepper jam were 14.34g in pectin, 255.6g in sucrose and 8.39ml in 50% citric acid solution. Maximized overall palatability of red pepper jam was 7.25 in 14.15g pectin, 257.08g sucrose and 8.19ml of 50% citric acid solution. The optimum preparation condition ranges on organoleptic properties of red pepper jam were 14.0~15.5g pectin, 225.0~257.0g sucrose and 8.0~8.2ml of 50% citric acid solution.

• Journal of the Korean Wood Science and Technology
• /
• v.45 no.4
• /
• pp.432-443
• /
• 2017

Maltodextrin and citric acid are two types of natural materials with the potential as an eco-friendly binder. Maltodextrin is a natural substance rich in hydroxyl groups and can form hydrogen bonds with lignoselulosic material, while citric acid is a polycarboxylic acid which can form an ester bond with a hydroxyl group at lignoselulosic material. The combination of maltodextrin and citric acid as a natural binder materials supposed to be increase the ester bonds formed within the particleboard. This research determined to investigate the bonding properties of a new adhesive composed of maltodextrin/citric acid for nipa frond particleboard. Maltodextrin and citric acid were dissolved in distillated water at the ratios of 100/0, 87.5/12.5, 75/25 and 0/100, and the concentration of the solution was adjusted to 50% for maltodextrin and 60% citric acid (wt%). This adhesive solution was sprayed onto the particles at 20% resin content based on the weight of oven dried particles. Particleboards with a size of $25{\times}25{\times}1cm$, a target density $800kg/m^3$ were prepared by hot-pressing at press temperatures of $180^{\circ}C$ or $200^{\circ}C$, a press time of 10 minute and board pressure 3.6 MPa. Physical and mechanical properties of particleboard were tested by a standard method (JIS A 5908). The results showed that added citric acid level in maltodextrin/citric acid composition and hot-pressing temperature had affected to the properties of particleboard. The optimum properties of the board were achieved at a pressing temperature of $180^{\circ}C$ and the addition of only 20% citric acid. The results also indicated that the peak intensity of C=O group increased and OH group decreased with the addition of citric acid and an increase in the pressing temperature, suggesting an interreaction between the hydroxyl groups from the lignocellulosic materials and carboxyl groups from citric acid to form the ester groups.

• Korean Journal of Plant Resources
• /
• v.33 no.3
• /
• pp.194-199
• /
• 2020

This study was carried out to get the information of Plum tree (192 germplasm) collected in Korea, and to evaluate the organic acid contents and fermentation solution. The organic acid content of fruit was 50.9 ± 6.0 mg/g, and which was composed of 55.5% of citric acid, 43.4% of malic acid and 1.1% of oxalic acid, and showed large difference among germplasms. Oxalic acid and malic acid made no differences in organic acid content according to flesh color, whereas citric acid and total organic acid contents were highest in orange color and lowest in whitish green. Malic acid, citric acid and total organic acid contents did not show differences among fruit weight groups, but oxalic acid content was highest at fruit weight of 5.1 ~ 10.0 g and lowest at more than 20.1 g. The sugar content of fermentation solution of fruit was 55.7 ± 1.6 °Brix and the harvest rate was 116.7 ± 8.7%. The correlation coefficients among fruit weight, the sugar content (°Brix) and harvest rate of fermentation solution were very low, and there were correlations of r=-0.551^⁎⁎ between fruit weight and oxalic acid, r=-0.767^⁎⁎ between malic acid and citric acid, and r=0.834^⁎⁎ between citric acid and total organic acid content.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.04a
• /
• pp.307-310
• /
• 2004

Micellar enhanced ultrafiltration (MEUF) is a surfactant-based separation process and it can remove heavy metal ions from aqueous stream effectively. However, it is necessary to recover and reuse surfactants for economic feasibility because surfactant is expensive. Foam fractionation was investigated for both anionic and cationic surfactant recovery. Chelating agent such as ethylenediaminetetraacetic acid (EDTA) was studied for the separation of heavy metals from surfactant solution. Anionic surfactants bound with heavy metals can be recovered by lowering pH (acidification). In this study, citric acid and imminodiacetic acid (IDA) were applied to release copper from sodium dodecyl sulfate (SDS) micellar solution and compared with EDTA. Precipitation of copper by ferricynide and sodium sulfide were also investigated. As a result, ca. 100 % of copper was released from SDS micellar solution by 5 mM of EDTA and citric acid. And 3.3 mM of ferricyanide formed precipitate with 82.7 % of copper. 5 mM of IDA and sodium sulfide released or formed precipitate 82.5 % and 58.9 % of copper, respectively. Citric acid is harmless to environments and ferricyanide precipitates with Cu easily. Therefore, it is considered that citric acid and ferricyanide have competiveness over a famous chelating agent, EDTA, for the separation of Cu from SDS solution.

• Preventive Nutrition and Food Science
• /
• v.9 no.2
• /
• pp.121-125
• /
• 2004

Effects of chemical treatment with a citric acid solution or ozonated water on microbiological changes in lettuce and cabbage during storage were studied. Fresh lettuce and cabbage samples were cut into small pieces and treated by soaking in either ozonated water or a citric acid solution. After treatment, populations of total bacteria, yeast and mold, and E. coli were determined. Numbers of microorganisms increased during storage, but ozonated water and citric acid treatments retarded the increase in microbial growth. Among treatments, 1 % citric acid treatment was the most effective in terms of microbiological change and inhibition of polyphenoloxidase (PPO). For lettuce, citric acid treatment decreased the microbial growth overall by 1.5 log CFU/g and inhibited the PPO activity by 80%. These results indicate that chemical-treated lettuce and cabbage retained a better quality than those of the control during storage.

• Food Science and Preservation
• /
• v.15 no.5
• /
• pp.754-759
• /
• 2008

The effect of citric acid-aqueous chlorine dioxide ($ClO_2$) treatment of radish seeds artificially contaminated with Salmonella typhimurium was studied. Radish seeds were inoculated by immersion, in more than 106 log CFU/g seed, of a suspension of S. typhimurium, dried, and stored sealed at $4^{\circ}C$ Radish seeds soaked in 200 ppm aqueous ClO2 solution for 10 min showed a bacterial reduction of 1.08 log CFU/g seed, and the lowering of microbial burden noted in seeds soaked in 2% (w/v) citric acid solution for 10 min was 2.89 log CFU/g seed. Next, radish seeds were exposed to 0.5% (v/v) glycerol solution for 10 min either before or after treatment with 200 ppm aqueous ClO2 or 2% (w/v) citric acid for 10 min. Glycerol exposure after citric acid treatment reduced bacteria by 3.46 log CFU/g seed, and glycerol treatment after aqueous $ClO_2$ treatment reduced the microbial burden by 2.14 log CFU/g seed. Both glycerol treatments yielded better elimination of S. typhimurium than did a single treatment with either citric acid or aqueous $ClO_2$. Radish seeds inoculated with S. typhimurium were treated throughout the entire growth period. Although radish seed treatment was effective, treatment by citric acid and aqueous $ClO_2$ after sprouting was not effective to eliminate S. typhimurium.