
Fruit juices and side-products enjoy a market of millions consumers all around the world. Citrus trees grow in about 50 countries and the fruits are very popular thanks to their good taste and quality. Fruit juice industry appeared when the production of citrus fruit exceeded consumption. Citrus fruit industry uses citrus fruits such as orange, tangerine, grapefruit, sweet lemon, and lemon for producing juice and other side products (Antil, 2011). Orange is one of the main citrus fruits and it is produced in different regions of the world so that orange fruits produced in each region has different and unique specifications. Mandarin orange (tangerine) is one of main types of orange with soft peel. Satsumas, which mainly grows in Japan, is a key member of Mediterranean region citrus fruits. Another type of citrus fruit is Tangor, which is something between orange and tangerine. Bitter orange is another largely grown type of orange, which is mostly used in South Europe for producing marmalade (Boeeing, 2012). Two groups of bitter chemical ingredients found in citrus juice are limonoids and flavonoids. Limonin is mostly found in seeds and tissue of the fruit. Bitterness caused by these combinations in citrus juice is very evident in orange juice. Namilin is another limonoid with bitter taste like limonin and plays a role in the general bitterness. Another source of bitterness is flavonoid naringin, which like limonin, is mostly found in the tissue and pulp compounds of the juice with a non-bitter isomer. Naringin and disaccharide neohesperidose (glucose + Rhamnose) that have a role to play in the bitterness and yield ester are products of naringine hesperiodose hydrolysis, which is a less bitter compound (Caladia, 2010). Yellow sour lemon is mostly produced in Italy and some of Mediterranean countries. Lemon is also produced at commercial scale in the USA. In addition to cooking, the yellow oval shape fruit is also used widely in making variety of fruit juices. Green lemon needs humid and warm climate and Egypt, Africa, Mexico, and West of India are main producers of the lemon. Mexico and India are two major producers of green lemon. In comparison with other types of lemon, green lemon is smaller (8-10cm), more spherical, and greenish-yellow in color with fresh and strong taste (Ecomos, 2012).