Physicochemical and rheological properties of red fruit juice concentrates and their sauces

Red colored fruits of strawberry, blackberry, Cornelian cherry, Urmu mulberry, sour cherry, sweet cherry and pomegranate juices were concentrated via rotary vacuum evaporator at 40 °C. The objectives of this study were to determine physicochemical properties of prepared concentrates, to investigate the thermal degradation kinetics of anthocyanins and total color difference in these concentrates and, to prepare sauces with these concentrates with and without gum at three different gum concentrations (0.15, 0.30 and 0.60 % (w/v)) via three different gums (locust bean gum, xanthan gum, ?-carrageenan) and, to analyze rheological properties of these sauces by power law model.All concentrates except sweet cherry concentrate had high phenolic content, total monomeric anthocyanins and exhibited high antioxidant activity. Monomeric anthocyanin degradation showed first order reaction kinetics. The zero order, ? rst order and a combined kinetic model were applied to the total color change and, combined kinetic model was selected as the best fit.Sauces prepared without gum has exhibited Newtonian flow characteristics, while sauces prepared with gums has exhibited non-Newtonian pseudoplastic flow characteristics. Pseudoplasticity has increased as gum concentration increased. Sauces prepared with xanthan gum at 0.30 % (w/v) gum concentration were selected as the best sauces.This study shows that red fruits are rich in phenolics; mainly they are anthocyanins-rich fruits; and they are natural antioxidants. Consumption of these fruits as fresh or as carefully prepared sauce with maintaining their attractive red color and nutritional benefits, may offer enjoyable and health promoting food stuff.Key words: Red fruits, physicochemical properties, kinetic, rheology, sauce