Chemical characterization of okra (Hibiscus esculentus L.) seed oil

Date

6-2001

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Milagros M. Peralta

Abstract

Pham, Patrisha J. College of Arts and Sciences. University of the Philippines Los Banos. June, 2001. CHEMICAL CHARACTERIZATION OF OKRA (Hibiscus esculentus L) SEED OIL.

Adviser: Dr. Milagros M. Peralta Members: Dr. Hidelisa P. Hernandez

Dr. Ma. Jamela R. Revilleza

This study aimed to characterize okra seed oil in terms of physico-chemical characteristics and partial characterization of its unsaponifiable fraction. The oil obtained by extraction using hexane at room temperature was a light, yellowish oil, which constituted 18.26 % of the entire seed (dry basis). The physico-chemical characteristics of the oil were found to be as follows: specific gravity - 0.945; saponification value -170.82; iodine value - 120.51; and peroxide value - 6.71. These values compared favorably with conventional edible oil sources like soybean and cottonseed oils.

Fatty acid analysis indicated that okra seed oil is unsaturated with the unsaturated fraction constituting 61.74 % of the total fatty acids. It is particularly rich in oleic acid (30.13 %) and linoleic acid (30.05 %). Palmitic acid (32.23 %) is another major fatty acid. The presence of linolenic acid (0.38 %), an important polyunsaturated fatty acid, makes the oil very promising for medicinal purposes.

The glyceride profile of the oil showed that triglycerides constituted 75 % of the lipid compounds, the other components being partial glycerides (17.5 %), free fatty acids (7.5%) and the unsaponifiable fraction (0.82%). HPLC analysis of the triglyceride molecular species indicated that the major triglyceride components corresponded to partition number (PN) 46 and 48. The fatty acid composition established by GC analysis and the retention times of 3 triglyceride standards were used to ascribe these peaks tentatively to the triglyceride species dioleoyl linolein (00L), dilinoleoyl palmitin (PLL) and tripalmitin (PPP). These components represented about 68 % of the triglyceride fraction based on their relative peak areas in the HPLC chromatogram.

The unsaponifiable fraction of okra seed oil constituted only 0.82 % of the oil and contained commercially important components such as tocopherols, carotenoids and sterols. The components were analyzed using .Thin Layer Chromatography (tic), High Pressure Liquid Chromatography (HPLC), Fourier-Transform Infrared Spectroscopy (FT-IR) and 'H Nuclear Magnetic Resonance Spectroscopy efl NMR). The carotenoids, chiefly xanthophylls (lutein) and small amounts of a and It carotenes, were identified to be the major components of the unsaponifiable fraction. Tocopherol content was analyzed to be about 133-mg/100 g oil. Among the tocopherols, y-tocopherol had the highest concentration but a and 6 tocopherols were also present in more than trace amounts.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2001 C4 P43

Document Type

Thesis

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