Citric acid

About: Citric acid is a research topic. Over the lifetime, 17745 publications have been published within this topic receiving 277125 citations. The topic is also known as: citrate & H3cit.

Cross-linking of cellulose and poly(ethylene glycol) with citric acid

Abstract: A novel approach to modifying native cellulosic fibres with poly(ethylene glycol) (PEG) impregnation and simultaneous cross-linking by citric acid (CA) was investigated. To understand the contributions of different components in the system, control references with just CA and cellulosic fibres (filter paper) were studied. The effect of sodium hypophosphite as a catalyst was also assessed. The results revealed that ester bonds are indeed formed in the cellulose–PEG–CA reaction system, as indicated by weight percentage gain (WPG) and FTIR analysis. The best results were achieved by using 5% CA and 10% PEG (calculated as weight-% from cellulose). In the reaction, the environmentally friendly CA prevents PEG from being leached out of cellulose during washing, resulting in promising future applications in dimensionally stabilized products based on cellulosic fibres.

Compositional changes of strawberry due to dehydration, cold storage and freezing–thawing processes

Abstract: Strawberry is an excellent source of food ingredients, although compositional changes might occur in improperly controlled processing, affecting product quality. In this article, changes in sugar composition (glucose, fructose and sucrose), citric acid, water and total soluble content, as induced by partial dehydration and freezing-thawing processes, were analyzed in strawberries (var. Camarosa). Osmotic dehydration (OD) with 65 °Brix sucrose solution, air drying (AD) at 45C, or combined treatments (OD-AD) were applied to reduce strawberries' water content to 70-85%. Fresh and dehydrated samples were frozen (-40C, 24 h) and stored (-18C, 30 and 180 days). All samples processed by OD and OD-AD showed a significant sugar gain, and depending on the dehydration treatment, total or partial sucrose hydrolysis was observed. Dehydration treatments caused small losses of citric acid. During the freezing-thawing process, drip loss and enzymatic action also cause changes in sugar concentration, especially in OD-treated samples.

Heated Ascorbic/Citric Acid Solution as Browning Inhibitor for Pre-Peeled Potatoes

Abstract: Treatment of pre-peeled potatoes with heated ascorbic acid (AA)/citric acid (CA) solution to extend shelf-life was investigated. Potatoes were abrasion or high pressure steam peeled, heated for 5-20 min in 1% AA + 2% CA at 45-55°C, cooled, and then dipped for 5 min in browning inhibitor (BI) solution containing 4% AA + 1% CA + 1% sodium acid pyrophosphate. Combined treatment inhibited potato discoloration for 14 days at 4°C, compared to 3-6 days with BI treatment alone. Raw material and treatment conditions were selected to minimize graying and textural abnormalities encountered with some treatments. Treatment with heated AA/CA may be an alternative to use of sulfites to control browning in pre-peeled potatoes.

Simultaneous determination of organic acids and vitamin C in green beans by liquid chromatography

Abstract: A method is described for determining and quantitating organic acids (oxalic, malic, citric, and fumaric) and vitamin C by liquid chromatography with a UV-visible detector that allows simultaneous monitoring at 2 wavelengths. The method was applied to samples of green beans (Phaseolus vulgaris L.). Recoveries were 97.8% for oxalic acid, 98.9% for malic acid, 98.7% for citric acid, 99.2% for fumaric acid, and 98.5% for vitamin C. Method precisions (coefficients of variation) were 1.7% for oxalic acid, 0.8% for malic acid, 0.9% for citric acid, 1.5% for fumaric acid, and 1.2% for vitamin C. Measurement precisions (coefficients of variation) were 1.32% for oxalic acid, 0.33% for malic acid, 0.62% for citric acid, 1.01% for fumaric acid, and 0.39% for vitamin C. Limits of detection were 0.025 mg/mL for oxalic acid, 0.022 mg/mL for malic acid, 0.024 mg/mL for citric acid, 1.0 x 10(-4) mg/mL for fumaric acid, and 2.7 x 10(-4) mg/mL for vitamin C.

Kinetics of inorganic and organic phosphorus release influenced by low molecular weight organic acids in calcareous, neutral and acidic soils

Abstract: Low molecular weight organic acids exuded by plants roots enhance inorganic P i release into soil solution and thereby increases plant-available Pi in soils. Low molecular weight organic acids may also induce organic P (P o ) release into soil solution, but kinetics of both Pi and Po displacement from the soil matrix into soil solution of agricultural soils is poorly understood, and the mechanism for P o release is not well explained. This study used kinetic experiments to determine the concentrations and release rates of P i and P o induced by oxalic acid, citric acid, and malic acid in calcareous, neutral and acidic soils. Kinetic data were well described by Elovich (r 2 = 0.801–0.993, P citric acid (0.61–2.82 mg kg –1 ) > malic acid (0.52–1.76 mg kg –1 ) and mainly resulted from the release of labile P o (NaHCO 3 -P o ) regardless of soil type. By contrast, oxalic acid was most effective in enhancing P i release from the HCl-P i (Ca-P i ) fraction of the calcareous soil, and citric acid was most effective in releasing Pi from the NaOH-Pi (Fe/Al-Pi) fraction of the neutral and acidic soils. Therefore, the mechanism for the kinetics of P o release induced by low molecular weight organic acids is ascribed to their ability to mobilize the labile P o (NaHCO 3 -P o ) rather than their ability to chelate cations (i.e. ,F e 3+ ,A l 3+ ) bound to P o in soil.