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.

Biochemical and Microbial Changes during the Storage of Minimally Processed Cantaloupe

Abstract: The effect of storage time on pH, titratable acidity, degrees Brix, organic acids, sugars, amino acids, and color of minimally processed cantaloupe melon (Cucumis melo L. var. reticulatus Naud. cv. Mission) was determined at 4 degrees C and 20 degrees C. Changes in most of the biochemical parameters with storage time were relatively slow at the lower temperature. At 20 degrees C, a 17% loss in soluble solids and a 2-fold increase in acidity occurred after 2 days. Organic acid content also increased considerably with time at this temperature as a result of the production of lactic acid. Oxalic, citric, malic, and succinic acids were the organic acids, and glucose, fructose, and sucrose were the sugars present in the freshly cut cantaloupe. Malic acid concentration decreased concurrently with lactic acid production indicating the possible involvement of anaerobic malo-lactic fermentation along with sugar utilization by lactic acid bacteria. The effect of storage on microbial growth was determined at 4, 10, and 20 degrees C. Gram-negative stained rods grew at a slower rate at 4 degrees C and 10 degrees C than the Gram-positive mesophilic bacteria that dominated microorganism growth at 20 degrees C. Eighteen amino acids were identified in fresh cantaloupe: aspartic acid, glutamic acid, asparagine, serine, glutamine, glycine, histidine, arginine, threonine, alanine, proline, tyrosine, valine, methionine, isoleucine, leucine, phenyl alanine, and lysine. The dominant amino acids were aspartic acid, glutamic acid, arginine, and alanine. Total amino acid content decreased rapidly at 20 degrees C, but only a slight decrease occurred at 4 degrees C after prolonged storage. Changes in lightness (L), chroma, and hue at both temperatures indicate the absence of browning reactions. The results indicate the potential use of lactic acid and lactic acid bacteria as quality control markers in minimally processed fruits.

Biodegradation of synthetic organo-metallic complexes of iron and aluminium with selected metal to carbon ratios

Abstract: Synthetic organo-ferric and organo-aluminous complexes with various metal :C ratios were prepared and incubated for 44 days in an Eutrochrept A1 horizon. Citric acid was used as a model of a natural soil acid. Fungal melanins synthesized by Epicoccum purpurescens were separated in fulvic acid-like and humic acid-like polymers and used as models for natural transformed soil organic matter. Under certain conditions, the biodegradation of such metal-organic complexes was slower than that of the free forms of the corresponding organic compounds. The intensity of this protective effect depended mainly on the metal to complexing functional groups molar ratio (M/CG) of the complexes and was also related to their aqueous solubility. For some organics, the protective effect was observed at ratios exceeding the saturation of their complexing sites, and sometimes needed a metal content exceeding more than twice their complexing capacity. In such cases, the formation of a flocculated metallic hydroxide trapping and wrapping the organic molecules is suggested to account better for the observed protective effect than chemical binding per se. As the solubility of the “humic” acids decreased faster than that of the “fulvic” ones when their metallic charge increased, the biodegradability of the former decreased more rapidly than that of the latter by metal complexing. For the same reasons, citric acid was more protected by complexing Al than Fe. The protective effect of both aluminium and iron against the biodegradation of all types of organic matter was high and of a comparable intensity at high M/CG molar ratios. These data are interpreted in terms of pedological processes.