Oranges constitute about 60% of the total citrus production in the world. The main portion of the production is used for the industrial extraction of citrus juice which leaves large amounts of residues, including peel and segment membranes. Peels consist of about 50 – 65% of the total weight of the fruit and remains as the primary byproduct. Waste from the production of orange juice results in unpleasant odor, soil pollution, and harborage for insects.
The waste products obtained from the oranges, especially its peel, can be used for further processing to obtain useful products. Recently, orange peel has been used as a raw material in industry. There are many enzymes present in the orange peel that also have valuable applications in the chemical and biotechnological industries.
The esterase is an enzyme which hydrolase enzyme that splits esters into an acid and an alcohol by hydrolysis. Esterases are widely distributed in plants, animals and fungi. Citrus fruit contains different types of esterases such as pectin methyl esterase (PME) and acetylesterase (AE) that hydrolyse simple esters into carboxylic acids. Usually, most parts of esterases are concentrated on the flavedo and albedo (peel) of the orange.
The esterase in citrus fruit has a lot of commercial interest. Orange fruit PMEs have an important role in the degradation of pectin during ripening of the fruit. Pectin methylesterase (pectin esterase) is the most abundant esterase in the orange peel which hydrolyses the pectin to methanol and polygalacturonic acid. The enzyme polygalacturonase further hydrolyses the polygalacturonic acid into monogalacturonic acid by breaking the glycosidic linkage.
The method used for the extraction of orange peel esterase was designed by Professor Bugg at the University of Southampton. This method explained how to prepare the orange peel extract, setup and monitor enzymatic hydrolysis and determine the Thin Layer Chromatography for its separation.
Seperation in TLC plate
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