Citrus organic acids

Carboxylic acids with one acid group are known as monobasic acids while those with two acid groups are dibasic acids. All acids with more than one acid group are in the class of polybasic acids. The simplest organic acid, formic acid, is responsible for the irritation of bee and ant stings. Vinegar is a 5% solution of acetic acid in water. The acetic acid is responsible for the characteristic sour taste. Citric acid, found in citrus fruits and used in soft drinks, is a tribasic acid with three carboxylic acid groups. The dibasic acid, adipic acid, is a major component of nylon. 

Organic Acids. The most predominate soluble constituents of citrus juice, following the sugars, are the organic acids and their salts. They represent about 10 percent of the total soluble solids in citrus juices. The proper ratios of sugar and the acids and their buffers give the citrus juices their delightful taste. 

The organic acids of citrus fruit include a group of carboxylic acids (23) with different acids predominant in various component parts of the fruit. Citric acid is the main acid in the juice, representing from 80 percent of the total acidity in juice from ripened oranges, about 90 percent of that of grapefruit and nearly all of that of lemon. The pH of the juice greatly affects the sourness of the product (24) and is, in turn, affected by the cations, especially potassium. The major acids in citrus peel are malic, oxalic (25), malonic (26), and quinic (27). 

Organic acids are metabolized in the body and should be considered as a source of energy. In the case of the salts of these acids, the organic portion is metabolized leaving the free cations to be combined with other anions. Thus, citrus juice is classed as an alkaline food (28). 

Distillation of citrus juices yields two volatile fractions, namely, aqueous essences and essence oils that are separated from each other by condensation of the distillate (7). Aqueous essence, the bottom layer of the condensate is comprised of organic acids, alcohols, aldehydes, esters, hydrocarbons, ketones, hydrogen sulfide, and oxides (10). Considering many components found in both cold-pressed peel oil and aqueous essence, essence oil has a flavor similar to that of the combined peel oil and aqueous essence (10). However, essence oil usually contains a larger amount of... 

C Citrus fruits contain citric acid, an organic acid. 

Various organic acids are commonly found to be natural constituents of fruit. Citric acid can be found in almost all fruits, especially citrus fruit and pineapple (Nikbakht, Sadrzadeh, and Mohammadi, 2007). Malic acid is also... 

Organic Acids. The ability of 33 strains of yeast to grow and produce pyruvic acid using dried citrus peel as a substrate was evaluated (22). Debaryomyces coudertii IFO 1381 and Candida utilis IF0 0396 produced yields of pyruvic acid near 82 mg/100 mL after 24 hours of fermentation at 30°C. Fermentation conditions were optimized with respect to nitrogen source (0.5% ammonium sulfate, dibasic phosphate concentration (0.1%), yeast extract concentration (0.01%), calcium carbonate concentration (1.0%), and magnesium sulfate concentration (0.01%). Pretreatment of citrus peel powder with the sodium form of Amberlite IR-120B was observed to enhance pyruvic acid production. Under optimized conditions, a maximum of... 

K. Matsumoto, K. Ishida, T. Nomura, and Y. Osajima, Conductometric Flow Injection Analysis of the Organic Acid Content in Citrus Fruits. Agric, Biol. Chem., 48 (1984) 2211. 

The mechanism for the conversion of carbonic acid intoC02 and water will be discussed in Chapter 21. Looking at the reaction above, it is clear that an acid must be present in order for baking soda to do its job. Many breads and pastries include ingredients that naturally contain acids. For example, buttermilk, honey, and citrus fruits (such as lemons) all contain naturally occurring organic acids ... 

Daito H, Tominaga S 1981 Constituents of sugars, organic acids and amino acids in the fruit juice at various locations within canopies of differenty trained Satsuma mandarin Citrus unshiu cultivar Sugiyama) trees. J Jpn Soc Hortic Sci 50 143-156... 

Monselise S P, Galily D 1979 Organic acids in grapefruit Citrus paradisi) fruit tissues. J Am Soc Hortic Sci 104 895-897... 

Sinclair W B, Eny D M 1947 Ether-soluble organic acids and buffer properties of citrus peels. Bot Gaz 108 398-407... 

L-Malic and citric acids are the major organic acids of fruits (Table 18.13). Malic acid is predominant in pomme and stone fruits, while citric acid is most abundant in berries, citrus and tropical fruits. (2R 3R)-Tartaric acid occurs only in grapes. Many other acids, including the acids in the citric acid cycle, occur only in low amounts. Examples are cis-aconitic, succinic, pyruvic, citramalic, fumaric, glyceric, glycolic, glyoxylic, isocitric, lactic, oxalacetic, oxalic and 2-oxoglutaric acids. In fruit juices, the ratio of citric acid to isocitric acid (examples in Table 18.14) serves as an indicator of dilution with an aqueous solution of citric acid. 

Ascorbic acid is photosensitive and unstable in aqueous solution at room temperature. During storage of foods, vitamin C is inactivated by oxygen. This process is accelerated by heat and the presence of catalysts. Ascorbic acid concentration in human organs is highest in adrenal and pituitary glands, eye lens, liver, spleen, and brain. Potatoes, citrus fruits, blade currants, sea buckthorns, acerola, rose hips, and red paprika peppers are among the most valuable vitamin C sources [1,2]. 

Buprofezin and its metabolites, p-OH-buprofezin and BF12, are hydrophobic under neutral conditions. Having the organic base part in their chemical structure, these compounds form water-soluble salts under strongly acidic conditions. The change in solubilities of these compounds influences the cleanup procedure. Four different residue analytical methods have been developed to measure buprofezin and its metabolites in plants (rice, citrus and tomato cucumber, pepper, tomato, squash and eggplant), soil and water ... 

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