D(+)-Malic acid in fruit juice
D(+)-Malic acid is an organic compound with the formula HO2CCH2CHOHCO2H. It is a dicarboxylic acid that is made by all living organisms, contributes to the pleasantly sour taste of fruits, and is used as a food additive.
D(+)-Malic acid(CAS NO:636-61-3) has two stereoisomeric forms (L- and D-enantiomers), though only the L-isomer exists naturally. The salts and esters of D(+)-Malic acid are known as malates. The malate anion is an intermediate in the citric acid cycle.
The only difference between the two is that they rotate the light shining on them in two different directions. L-Malic acid is produced naturally in fruits. 90% of the acid in apples is D(+)-Malic acid(CAS NO:636-61-3). When D(+)-Malic acid is produced synthetically, a mixture of the two isomers is obtained which is called DL-Malic acid (because it contains both D- and L-Malic acid). When you eat DL-Malic acid, your body digests it in just the same way as it does for L-Malic acid. It is part of the Krebs cycle.
D(+)-Malic acid was first isolated from apple juice by Carl Wilhelm Scheele in 1785. Antoine Lavoisier in 1787 proposed the name acide malique which is derived from the Latin word for apple, mālum. It contributes to the sourness of green apples. It is present in grapes and in most wines with concentrations sometimes as high as 5 g/l. It confers a tart taste to wine, although the amount decreases with increasing fruit ripeness. The taste of this chemical is very clear and pure in rhubarb, a plant for which it is the primary flavor.
The process of malolactic fermentation converts D(+)-Malic acid to much milder lactic acid. It occurs naturally in all fruits and many vegetables, and is generated in fruit metabolism.
D(+)-Malic acid, when added to food products, is denoted by E number E296. It is the source of extreme tartness in USA-produced confectionery, the so-called extreme candy. It is also used with or in place of the less sour citric acid in sour sweets. These sweets are sometimes labeled with a warning stating that excessive consumption can cause irritation of the mouth. It is approved for use as a food additive in the EU, USA and Australia and New Zealand (where it is listed by its INS number 296).
The addition of D(+)-Malic acid to fruit juice, to increase the acid content for example, is strictly illega l, although the EC permits its addition to wine. The naturally occurring form of D(+)-Malic acid in fruits is the L-enantioner. Synthetically produced this chemical consis ts of the racemic D/L mixture. The much higher cost of the L-enantiomer, which is currently 20 times that of the D/L mixture,discourages its use as an adulterant. Therefore, the measurement of D(+)-Malic acid alone is sufficient to detect the illegal addition of synthetic Malic acid. A sample of orange juice sampled during 1991 and analysed also by the L eatherhead Food RA contained 103 ppm of D(+)-Malic acid (authentic orange juice should not contain any).
D(+)-Malic acid can be measured spectrophotometrically using the enzymatic method, recently developed by Beutler and Wurst, available also as a test kit from Boehringer Mannheim GmbH.
A survey carried out by the Ministry of Agriculture Fisheries and Food in the U.K. in January 1991, co mpared methods for detection of added substances in leading brands of or ange juice, of 17 samples analysed, 10 contained D(+)-Malic acid , as a consequence of adulteration.
Want to learn more information about D(+)-Malic acid, you can access the guidechem.com. Guidechem.com is just a place for you to look for some chemicals. Guidechem provide the most convenient conditions for the international buyers and let these leads benefit all the business people.