The evaluation of qualitative indicators of chosen species of small fruits

The fruits of elderberry (Sambucus nigra L), bilberry (Vaccinium myrtullus L.), blackberry (Rubus fruticosus L. agg.) and raspberry (Rubus idaeus L.) due to expected higher content of anthocyans, have been studied. The aim of this work was to determine the level of vitamin C, organic acids, sugars, dyes and fibre in selected species of wild fruits collected from different localities of Slovakia (Kysuce, Spiš and six sites of southern Slovakia). For the determination of selected qualitative indicators of small berries the following methods were used: vitamin C by automated laboratory analyzers EcaFlox 150 GLP, content of organic acids by titration, sugars according by the method to Somogyi, natural dyes were analyzed by HPLC with measuring the intensity of staining in alcoholic extract. The highest values of vitamin C were obtained from raspberry (25.65 mg per 100 g) and elderberry (18.73 mg per 100 g); bilberry proved higher quantity of organic acid (6.40 mg per 100 g) and natural pigments (7.68 g per kg). We found out that elderberry had the highest quantity of sugar (14.20 mg per 100 g) and fibre (7.68 g per kg). During sterilization, the value of vitamin C decreased by 96.4% at blackberries and by 91.3% at bilberries. As for bilberries, the quantity of organic acid dropped to 49.1% and the quantity of natural pigments to 43%. In blackberries, the quantity of organic acid increased to 5.12% and the quantity of natural pigments remained stable. After sugar solution adding, the quantity of sugar of stewed fruit increased about 100%. Our results indicated the changes in quality during sterilization of berries.