Investigation of mineral composition during processing of wild berries

The article presents results of studies of the mineral composition of wild berries and their constituent parts (peel, pulp). Blueberries, bilberries, cranberries and lingonberries were picked out on the territory of the Vyborg district of the Leningrad Region. Berries sorted by quality and degree of maturity and crushed; the juice and pulp were separated by pressing and filtration. The yield of juice depended on the type of berries and was minimal for blueberries. Berries, peel and pulp were dried to constant weight at a temperature of 50 °C. The composition of the mineral elements was determined in the native remainder of whole berries and their constituent parts by X-ray fluorescence on the energy dispersive X-ray fluorescence spectrometer "Rigaku Nex CG", USA. The method used makes it possible to obtain the composition of mineral elements in the form of oxides. All berries had a typical composition of elements with a predominance of potassium and calcium. The content of potassium berries were as follows: bilberries > lingonberries > blueberries> cranberries. The highest content of calcium was in blueberries; phosphorus prevailed in lingonberries. In the trace elements were identified: iron, copper, zinc, nickel, manganese, silicon, vanadium, titanium. Vanadium was found only in blueberries and bilberries. During the processing of berries, mineral elements were redistributed. Potassium oxides are distributed in all parts of the berries, calcium, titanium and vanadium oxides are found predominantly in the skin and in the pulp of berries. Most of the oxides of macro-elements (such as phosphorus, sulfur, chlorine) and trace elements (such as iron, zinc, manganese, silicon, copper, nickel) are contained only in the juice.