Food & Nutrition

Arab Journal of Food & Nutrition
26. Extraction and Characterization of Oil from Tomato Pomace (1998)
Amal Suleiman Awad Joher
Supervisor:Dr. Ayed S. Amr
Tomato pomace, a waste product in the form of skins, fibers, and seeds, is the
major byproduct of the tomato processing industry in Jordan.
Oils from tomato pomace, seeds and peels were extracted with n-hexane. Their
physical and chemical properties as well as fatty acids composition were studied. The
investigated crude tomato seed, pomace, and peel oils were characterized by a pale
yellow color. The physicochemical properties of such oils were similar to soybean oil.
The oil content was determined for the three varieties (Shams, Wafa, and Gardina),
results indicated that seeds, pomace and peels of Shams contained 23.6%, 12.5% and
4.9% oil (DMB) respectively, and that the oil yield varies significantly depending on
tomato varieties. The highest in its oil content on DMB was Shams and the lowest was
Gardinia.
There were no significant differences in the values of specific gravity, refractive
index and viscosity among tomato seed and pomace oils. Saponification number of
tomato seed oil was significantly higher than the values obtained for both tomato
pomace and peel oils. The iodine value of peel oil (50.75) differed significantly from
that of both pomace and seed oils which were 101.06 and 118.61, respectively.
According to the iodine value, the peel oil could be classified as non-drying oil while
pomace and seed oils could be classified as semi-drying oils.
Peroxide value was used to evaluate the oxidative rancidity of the extracted oils.
The methyl esters of the oils were analyzed by gas liquid chromatography (GLC)
to determine their fatty acid composition. The fatty acid composition of the seed,
pomace and peel oils indicated that the oil is rich in linoleic acid 57.04%, 58.35% and
53.51% respectively. Linoleic acid was the major unsaturated fatty acid followed by
oleic acid. Palmitic acid was the major saturated fatty acid in the three oils followed by
stearic acid. Peel oil contained small amounts of lauric and myristic acids which were
not detected in both tomato pomace and seed oils. The ratio of saturated:unsaturated
fatty acid was the highest in peel oil (0.33:1) as compared to the other two oils.
Moreover, the extracted oils were free from long chain fatty acids (>C18), and
were rich in unsaturated fatty acids, with their degree of unsaturation exceeding 80%
in both seed and pomace oils, and 70% in peel oil.
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Volume 36 11, No. 25, 2011