Sugars, acids, ethyl β-d-glucopyranose and a methyl inositol in sea buckthorn (Hippophaë rhamnoides) berries

Sea buckthorn berry is a rich source of nutrients and bioactive components beneficial for human health. Sugars and acids play an important role in determining the sensory properties of the berry. Sugars, acids, ethyl β-d-glucopyranose and a methyl inositol were analysed in berries of three subspecies (Hippophaë rhamnoides ssp. sinensis, rhamnoides and mongolica) collected from China, Finland and Russia over four consecutive years. Fructose and glucose were the major sugars, and the dominating acids were malic and quinic acids. Origin and harvesting date have significant impacts on sugars, acids and sugar/acid ratio in the berry. During the harvesting period, the sugar content followed different changing patterns in berries of different subspecies. Ethyl glucose dominated in the sugar fraction of ssp. rhamnoides but existed only in trace amounts in the other two subspecies. In ssp. rhamnoides, the level of ethyl glucose increased during the harvesting period; the increase was accompanied by a decrease in glucose content, indicating the presence of a biochemical pathway converting glucose into its derivatives. A methyl inositol was identified for the first time in sea buckthorn with higher levels found in ssp. sinensis than in the other two subspecies. The levels of ethyl glucose and methyl inositol may be important sensory and nutritional quality factors of sea buckthorn berry. The data presented by this study provide important chemotaxonomic information characterising different subspecies of sea buckthorn and useful guidance for breeding, harvesting, and industrial utilisation of sea buckthorn.