Functional properties of omani dates (Phoenix dactylifera L.)

Three sun-dried date varieties grown in Oman, namely Fard, Khasab, and Khalas, were examined for their proximate composition and functional constituents; dietary fiber, selenium, antioxidant, carotenoids, phenolics as well as phenolic acids. The study was conducted on dried dates due to their higher consumption compared with fresh dates. All results are expressed as mean value standard deviation (n= 3) on a fresh weight basis. Date varieties were found to be low in fat and protein, but rich in dietary fiber and antioxidants. They were found to be a high source of energy (278-301 kcal/100 g), due to the high carbohydrate content. Total dietary fiber content of dates varied from 6.26 to 8.44 g/100 g, of which 84-94% was insoluble fiber. Dates were found to be a good source of antioxidant constituents including selenium (0.356 to 0.528 mg/100 g), total antioxidants (8212-12543 mu mol of Trolox equiv/g), carotenoids (0.92-2.91 mg/100 g), and phenolics (217-343 mg of ferulic acid equiv/100 g). Date varieties had different levels and patterns of phenolic acids. Nine phenolic acids (gallic, protocatechuic, p-hydroxybenzoic, vanillic, caffeic, syringic, p-coumaric, ferulic, and o-coumaric acid) were tentatively identified. Ferulic acid was the major phenolic acid for all date varieties. The total content of phenolic acids ranged between 20.24 mg/100g for Khasab and 63.41 mg/100g for Khalas. Of the date varieties studied, Khalas, which is considered to be of premium quality, had higher antioxidant activity, total carotenoids and phenolic acids than other varieties. These results suggest that all date varieties serve as a good source of natural antioxidants and could potentially be considered as a functional food or functional food ingredient.