Study of the tannin and fatty acid composition of acorn of chestnut- leaved oak (Quercus castaneifolia C. A. Mey.) in Golestan province

Oak acorn is an edible nut with a long history in human nutrition. In this study، the kernel fatty acid composition and tannin contents of chestnut leaved oak (Quercus castaneifolia C. A. Mey.) was investigated in Alangdarreh forest in Golestan province. Oil extraction from kernel was carried out by Soxhelt apparatus using n-hexane as solvent. Fatty acids were methyl esterified before quantitative and qualitative gas chromatography analysis. The results revealed the presence of saturated fatty acids including palmitic acid (C16:0)، margaric acid (C17:0)، stearic acid (C18:0) and unsaturated fatty acids such as oleic acid (C18:1)، linoleic acid (C18:2)، linolenic acid (C18:3) and gadoleic acid (C20:1). The net yield of extraction for oil was 7. 49%، constituting 81. 13% unsaturated and 18. 87% saturated fatty acids. The three major identified fatty acids and their respective relative amounts were linoleic acid (49. 57 mg. g-1 oil)، oleic acid (34. 74 mg. g-1 oil) and palmitic acid (20. 58 mg. g-1 oil). Tannin extraction was carried out by water as solvent. The total tannin content of acorn was determined using gallic acid as standard spectrophotometrically. Results showed that the total tannin content of acorn was equivalent to about 178. 13 mg galic acid. g-1 dry weight and the total oil content of acorn was 1. 49 mg. 20 g-1 dry weights.