Nutrients of fresh strawberries and products of its processing taking into account varietal characteristics

Abstract

In the context of a deficiency of some essential nutrients in the diet of the majority of Russian population, studies aimed at evaluation of the accumulation of nutrients in plant foods that determine the nutritional value and contribute to the improvement of the nutritional structure of the human diet are relevant. The aim of this work was to evaluate content of macro- and micronutrients that determine nutritional value in strawberries, taking into account varietal characteristics, and to assess its opportunity to improve the structure of human nutrition when eaten fresh and in processed products. Material and methods. The study included 3 varieties of strawberries bred by the Institute and 10 varieties of foreign breeding of different ripening periods, which are most common in industrial plantings when cultivated in the south of Russia. When conducting a chemical-technological assessment of strawberries harvested over three years (2017-2019), the following was determined: soluble solids; organic acids, sugars, vitamin C, amino acid composition, mineral substances; catechins, polyphenols, anthocyanins, leucoanthocyanins, pectin substances; aromatic substances, firmness of berry pulp. Results. Strawberries of different varieties differ from each other not only in technical parameters (shape, size, color, hardness), but also in biochemical characteristics (content of carbohydrates, vitamins, minerals, etc.). Strawberries accumulate 7.8-11.0% soluble solids, 5.9-8.3% - sugars (which are mainly represented by glucose (2.16-2.92%) and fructose (2.29-2.98%); 0.6-0.8% - pectins; 0.8-1.5% - acids (mainly citric acid). Strawberries are a source of vitamin C, which content in the studied varieties ranged from 48.8 (Asia variety) up to 67.8 mg/100 g (Marmolada variety); catechins varied in the range 43.2-108.8 mg per 100 g, anthocyanins - 51.5-90.0 mg/100 g, leuco-anthocyanins - 92.3-166.1 mg/100 g. The mineral composition is characterized by a low content of minerals (in 100 g: potassium - 75.8-123.0 mg, calcium - 22.3-30.2 mg, magnesium - 6.3-10.3 mg) and a high accumulation of iron (0.85-1.34 mg/100 g). The presence of a complex of biologically active substances determines the demand for strawberries both for fresh consumption and as a raw material for many types of processing and freezing. As a result of the conducted studies of the chemical composition of strawberries, taking into account the technological requirements for this raw material (content of soluble solids, sugars, vitamins), the following varieties are recommended for processing: Marmolada, Molling Pandora, Florence, Elsanta, Tair. Berries of the following varieties are suitable for freezing: Marmolada, Alba, Arosa, Nelly, Onda, as the most fully preserving the original quality of berries, having a low juice yield and a high tasting rating. Conclusion. On the basis of the comprehensive studies of the quality of berries, promising varieties of strawberries were identified for cultivation in the south of Russia, characterized by high nutritional value, excellent taste, usage in food consumption both fresh and frozen, as well as in the production of canned products, including obtaining foodstuffs for functional purposes.