Quercus robur (english oak) seed: a potential energy, oleic and cis-linoleic acid rich nutritional supplement in South Africa

Although plentiful in the South African urban areas where it is used as an ornamental tree, Quercus robur (Q. robur; English Oak), is not indigenous. The tree produces an abundance of fruit (acorns) which contain seeds that are left to decay despite their potential as sources of biomass. To establish the potential of the tree, we determined the proximate, mineral, fiber, amino acid, fatty acid and phytate-phosphate content of dehulled Quercus robur seed. The seed had a dry matter (DM) content of 91.56% and a gross energy content of 17.38 MJ kg-1. Of the DM content 88.65% was organic matter, 8.77% crude protein (CP) and 4.55% lipid. Calcium (0.07%) and phosphorus (0.11%) concentration were low. Amino acids constituted 94.86% of the CP. Saturated fatty acids (SFAs) constituted 18.18% of the lipid content with palmitic acid the dominant SFA while the monounsaturated fatty acids (MUFAs) made up 42.04%. Oleic acid (OA) constituted 97.66% of the MUFAs. Polyunsaturated fatty acids made up 30.22% of the lipid content with cis-linoleic acid (28.71%) dominating. Due to the high energy content, a preponderance of OA and cis-linoleic acid and a low phytate-phosphate and fiber content, Q. robur seed could potentially be exploited as an energy dense and healthful nutritional supplement. (author)