Crop description. Azadirachta indica—commonly known as the neem tree, nim, margosa, veppam, cho do, or nilayati nimb—belongs to the family Meliaceae and can be found in dry tropical forests (see Fig. 4.11). The major producing countries are India, Sri Lanka, Burma, Pakistan, tropical Australia, and Africa. The evergreen neem tree grows up to 18 m high. The fat content of the kernels ranges from 33 to 45% [77]. The fatty acid content includes 42% oleic acid, 20% palmitic acid, 20% stearic acid, 15% linoleic acid, and 1.4% arachidic acid. Good quality ker­nels yield 40-50% oil. The cakes, which contain 7-12% oil are sold for solvent extraction. Neem oil is unusual in that it contains nonlipid asso­ciates often loosely termed as bitters and organic sulfur compounds that impart a pungent, disagreeable odor [88].

Main uses. The products of the neem tree are known to be antibac­terial, antifungal, and antiparasitic. The main uses are in soaps, teas, medicinal preparations, cosmetics, skin care, insecticides, and repel­lents. Neem twigs are used as tooth brushes and ward against gum disease. Neem oil, which is extracted from the seed kernel, has excel­lent healing properties and is used in creams, lotions, and soaps. It is also an effective fungicide. The bitter cake after the extraction of oil

Figure 4.11 Azadirachta indica. (Photo courtesy of Food and Agricultural Organization of the United Nations [www. fao. org].)

has no value for animal feeding but is recognized as both a fertilizer and nematicide [88]. Besides medical use, esters of neem oils have some important fuel properties that can be exploited for alternative fuels for diesel engines [78]. Nabi et al. have produced biodiesel from neem oil by using 20% methyl alcohol and 0.6% anhydrous lye catalyst (NaOH). The temperature of the materials was maintained at 55-60oC. Compared with conventional diesel fuel, exhaust emissions including smoke and CO were reduced, while NOx emission was increased with diesel-biodiesel blends. However, NOx emission with diesel-biodiesel blends was slightly reduced when exhaust gas recirculation (EGR) was applied. According to the results, Nabi et al. have recommended the use of the ester of this oil as an environment-friendly alternative fuel for diesel engines [117].