Full Length Research Paper

Some chemical and physico-mechanical properties of pear cultivars

Ismail Ozturk¹*, Sezai Ercisli², Fatih Kalkan¹ and Bunyamin Demir¹

¹Department of Agricultural Machinery, Faculty of Agriculture, Ataturk University 25240 Erzurum-Turkey.

²Department of Horticulture, Faculty of Agriculture, Ataturk University 25240 Erzurum-Turkey.

*Corresponding author. E-mail: iozturk@atauni.edu.tr.

Nomenclature: L- fruit length, mm; R_d- density ratio, %; W- fruit width, mm; e- porosity, %; R_a -aspect ratio, % m_s- static coefficient of friction ; D_g- geometric mean diameter, mm; F_r- rupture force, N; f- sphericity; D_r- deformation at rupture, mm; S- surface area, cm^2.; E_a- energy absorbed by fruit until rupture, Nmm; V- fruit volume, cm³; Q- hardness, Nmm^-1; r_f-  fruit density, kgm^-3; P - toughness, mJcm^-3; r_b- bulk density, kgm^-3; a- angle of tilt, deg.

Accepted 28 January, 2009

Two pear (Pyrus communis L.) cultivars namely Deveci and Santa Maria, which dominate pear production in Turkey, were analyzed for several physico-mechanical (moisture, fruit dimensions, aspect ratio, geometric mean diameter, sphericity, surface area, projected area, fruit mass, fruit volume, fruit density, bulk density, density ratio, porosity, coefficient of static friction, rupture force, deformation, absorbed energy, fruit firmness, toughness, hardness and skin color values) and chemical (protein, fatty acids, ash, pH, acidity, vitamin C, total soluble solids, antioxidant activity, total phenolic content and mineral elements) properties. There is a statistical difference between cultivars in terms of most of the physico-mechanical and chemical properties. The average fruit mass ranged from 190.36 (cv. Santa Maria) to 289.85 g (cv. Deveci). The bulk density, porosity, rupture force and fruit hardness determined as 365.84 - 543.12 kgm^-3; 45.67 - 66.57%; 23.04 - 39.59 N and 9.87 - 13.74 N/mm between cultivars.

Key words: Fatty acids, mechanical properties, mineral elements, pear (Pyrus communis L.).