The chemical composition of the fruit of Pyrus L. genus representatives

Abstract

Aim. The article aimed at determining the content of the basic elements of the chemical composition (total contentof water, titrated acids and mass fraction of dry soluble substances) in the fruits of Pyrus L. genus representatives and the acidity of their cell sap (pH). Methods. The analyzed fruits had been gathered from plants of the species and pear cultivars collections growing in the National Dendrological Park “Sofiyivka” of NAS of Ukraine and Uman National University of Horticulture (P. communis L., P. pyrifolia (Burman f.) Nakai and ‘Glek’, ‘Kniahynia Olga’ and ‘Clapp’s Favorite’), as well as at M. M. Gryshko National Botanical Garden of NAS of Ukraine (P. betulifolia Bunge, P. calle-riana Decne, P. elaegrifolia Pall., P. pashia Buch.-Ham. ex D. Don., P. georgica Kuth.). The chemical composition of the fruits had been determined by conventional methods using pH tester (pH-150M), a refractometer (URL-1), and an atmospheric tray dryer (SUP-4). The level of titrated acids (in terms of malic acid) had been defined by the volume titration method according to DSTU EN12147–2003. Results. The pH in the studied Pyrus fruits varied from 3.2 to 4.8, indicating the acidic response of the cell sap of the fruits of the studied species and cultivars of pear. The water content of pear cultivars (85.83–90.0%) was higher than in Pyrus species (67.36–79.56%) except for P. pyrifolia (87.1%). In most of the studied Pyrus representatives (‘Glek’, P. betulifolia, P. calleriana, P. communis, P. pashia, P. georgica, P. elaegrifolia), the titrated acid index ranged from 0.18 to 0.25%. The lowest rates were in P. pyrifolia (0.11%) and ‘Kniahynia Olga’ (0.09%), and the highest ones were in the ‘Clapp’s Favorite’ (0.31%). The more soluble solids had been found in P. betulifolia, P. georgica, P. elaegrifolia, P. pashia, and P. calleriana (14.6–16.1%), whereas in the other species and cultivars their content did not exceed 8.2–12.4%. Conclusions. Thus, according to the complex of indicators, the fruits of species and cultivars of the genus Pyrus contained 67.36–90.00% of water, 8.2–16.1% of soluble solids, 0.09–0.31% of titrated acids, in the acidic cell sap reaction with pH was of 3.21 to 4.80. Based on the data obtained, the cultivars of ‘Clapp’s Favorite’ and ‘Kniahynia Olga’ can be used for fresh consumption, ‘Glek’—for drying, and P. pyrifolia — for involvement in the breeding programmes.