Citrus seed oil

TABLE 2. Physicochemical Characteristics of Different Citrus Seed Oils. 

Analyzed by thin layer chromatography, cmde citrus seed oils are reported to have eight classes of chemical constituents triacylglycerols, free fatty acids, diacyl-glycerols, monoacylglycerols, sterols, phospholipids, alcohols, and hydrocarbons... 

Table 6). Triacylglycerols are the major oil class in all citrus seed oils, followed by free fatty acids and then diacylglycerols. The presence of partial acylglycerols and free fatty acids is due to partial enzymatic hydrolysis of reserve triacylglycerols during seed storage (9). 

Crude citrus seed oils need to be refined before use as edible oils. Only triacylglycerols, diacylglycerols, and polar lipids remain after degumming, refining, bleaching, and deodorization. However, trace amounts of phosphatides (lecithin) and plant sterols may also remain in the oil (37). 

Citrus seed oil, as a potential edible oil, serves as a good source for essential fatty acids. More than 60 fatty acids have been found in various citrus seed oils, among which unsaturated fatty acids are present in a high amount (>65%)... 

Saturated fatty acids were less abundant than their unsaturated counterparts in citrus seed oils and consisted mainly of palmitic (C16 0) and stearic (C18 0) acids... 

Table 7 shows the fatty acid composition of different citrus seed oils. The ratio of unsaturated to saturated fatty acids is approximately 2 1 (9), although this ratio was reported to be in the range of 3-5 1 by Nagy (35). Generally, different varieties, cultivar, location, storage condition, and harvesting time of citrus fruit may lead to this variation. Table 8 shows the content of the six major fatty acids in different citrus seed oils these are linoleic (C18 2), palmitic (C16 0), oleic (C18 l), linolenic (C18 3), stearic (C18 0), and palmitoleic (C16 l) acids. 

TABLE 8. Major Fatty Acids in Citrus Seed Oils (%). ... 

Citrus seed oil, another byproduct in citrus industry, is required to have high stability for cooking purposes. Citrus seed oil is subject to oxidative changes because of the presence of a high percentage of unsaturated fatty acids. The oil is readily oxidized in the presence of air, generating hydroperoxides, alcohols, aldehydes, ketones, hydrocarbons, and carboxylic acids as the primary, secondary, and tertiary oxidized products, respectively. 

Unlike citrus peel oil, citrus seed oil is mainly used after refining as edible oil and a source of essential fatty acids. Refined citrus seed oil is widely used in margarines, shortenings, salad dressings, and salad and cooking oils. Meanwhile, crude citrus seed oils are useful in the preparation of fatty acid derivatives, soap and detergent, and for the treatment of leather and textile (1). 

Rouseff and Nagy (1982) used a direct solvent extraction method for citrus seeds. Oils were removed from seed meals with hexane in a Soxhlet extractor. The seed residues were then extracted with chloroform. The hexane fraction was saved for analysis of obacunone, which is somewhat soluble in hexane. 

Table 7.1 Range of fatty acid composition in Florida citrus seed oils...

The ranges of fatty acid composition for several Florida citrus seed oils are shown in Table 7.1. Filsoof and Mehran (1976) studied the fatty acid composition of eight different citrus seed oils and found the fatty acid profiles to be very similar for the oils of oranges, limes and sweet lemons. This similarity of fatty acid composition has the advantage that any change in the availability of given varieties may be expected to have no effect on the quality of the finished oil. 

The physical constants of citrus seed oil reported by Braddock and Kesterson (1973) are given in Table 7.2. Refined oil is bland and pale yellow in color and could be used like other cooking and salad oils. Helmy (1990) studied the effect of refining on color and reported that refined oil from orange, bitter orange, mandarin and lemon ranged from 9 to 13 lovibond units (yellow) and bleached oils measured 1 lovi-bond unit. The oil has been evaluated for edible purposes as well as industrial applications (Hendrickson and Kesterson, 1961, 1963, 1964, 1965 Kaplan, 1941 Stambovsky, 1942). 

Braddock, R.J. and Kesterson, J.W. (1973) Citrus seed oils. Bulletin 756, Agricultural Experiment Station, University of Florida, Gainesville, 30 pp. 

Filsoof, M. and Mehran, M. (1976) Fatty acid composition of Iranian citrus seed oils. J. Am. Oil Chem. Soc. 53, 654-655. 

Citrus seed oil, as a potential edible oil, serves as a good source for essential fatty acids. More than 60 fatty acids have been found in various citrus seed oils, among which unsaturated fatty acids are present in a high amount (>65%) (35, 38). Linoleic (>30%), oleic (>18%), and hnolenic (2-12%) acids are the most predominant unsaturated fatty acids present (9). Lemon, lime, and citron oils contain the highest amount of linolenic acid. In addition, very small amounts of myristoleic acid (C14 l) in polar lipids fraction, myristoleic (C14 l) and palmitoleic (C16 l) acids in diacylglycerols fraction, and myristoleic (C14 l) and eicosaenoic (C20 l) acids in triacylglycerols fraction of citrus seed oil were also identified (39). 

Saturated fatty acids were less abundant than their unsaturated counterparts in citrus seed oils and consisted mainly of palmitic (C16 0) and stearic (C18 0) acids at 22-31% and 1-6%, respectively. Arachidic (C20 0), lauric (C12 0), and myristic (C14 0) acids were found in trace amounts compared with other fatty acids (9, 35,40). 

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