Physicochemical and Rheological Properties of Wild Medlar Concentrate

Wild medlar fruit (Mespilus germanica) is rich in sugars and organic acids. In this study, wild medlar concentrates in four concentrations of 14, 28, 42 and 56 %(°Brix), preparation and physicochemical properties including pH, acidity, density and color, and rheological properties (at 20, 30, 40, 50, 60 and 70 ° C) were studied. The pH was in the range from 3.37 to 3.62 and acidity according to citric acid was in the range of 1.05 to 3.90 %. Density of concentrated sample (56 %) was 1277 kg/m³. Color of samples was analyzed using image processing technique and image parameters including L*, a* and b* for the sample with a concentration of 56% was 20.54, 1.69 and 1.36, respectively. With increasing in concentration, the sample was darker and L* index decreased. Concentrate used in all concentrations showed Newtonian behavior and viscosity increases with increasing concentration. With increasing in temperature from 20 to 70 ° C, the viscosity of the concentrate (56 %), decreased from 2517 to 223 mPa.s. The magnitude of activation energy was found in the range of 9.59–43.39 kJ/mol K.