DATE PALM PHOENIX DACTILIFERA L. SEED OIL: VARIETY EFFECTS ON PHYSICOCHEMICAL CHARACTERISTICS, FATTY ACID COMPOSITION, STEROL AND TOCOL CONTENTS

Abstract

The date palm (Phoenix dactylifera L.) grows in the world's arid and semi-arid regions, particularly in the majority of Middle Eastern countries. It has played an important role in the survival of many ancient civilizations. It is regarded as a valuable nutrient, but it also plays an important role in the economies of date-producing countries. Date palm seeds are commonly described as waste after consuming their pulp by industries or individuals. However, date pits contain a valuable source of edible oil characterized by a high content of unsaturated fatty acids, sterols, tocopherols, and tocotrienols. The main purpose of this study was to analyze the chemical composition and quality parameters of Date Seed Oil (DSO) extracted from ten native date palm seed (Phoenix Dactilifera L.) varieties and compare them to the literature results. The choice of the seed variety was based on popularity and quality. The lipid extraction was carried out by a soxhlet apparatus using a standard solvent with a seed isolated from a matured date. The yield ranged from 2.94% to 8.06% depending on the variety. Gas chromatography coupled to mass spectroscopy (GC/MS) and high-performance liquid chromatography (HPLC) were used to determine the composition of the fatty acids, sterols, and tocols (tocopherols and tocotrienols) in the extracted oil. Our results indicate that DSO is rich in poly and unsaturated fatty acids (PUFA+MUFA = 48.89% to 60.77%) with oleic acid (C18:1) as the predominant fatty acid (from 52.60% to 42.13%). On other hand, eight sterols were identified and the mean content ranged from 346.97 to 816.60 mg/100g of oil. Also, a high amount has been recorded in tocols ranging from 1937.14 µg/g to 3844.06 µg/g. Indeed, the predominant tocols in DSO were alpha-tocotrienols and alpha-tocopherols. Likewise, the quality parameters indicate that DSO has excellent thermal and oxidative stability and is generally safe to consume. In fact, the peroxide value (PV) recorded a mean of 3.96 to 6.33 meq O2/kg. The iodine value of DSO samples goes from 48.84 to 60.59 g I2/100 g oil. The saponification value (SV) changed between 214.85 and 225.59 mg KOH/g of oil. However, the coefficients of extinction K232 and K270 were lower than the specified limitations. According to the findings, date seed has the potential to be used as a renewable resource while also adding value to pharmaceutical, cosmetic, food, and agricultural products.