(444d) Effect of Manothermosonication (Mts) on Quality of Orange Juice

Heat treatment that has been commercially used to inactivate microorganisms and enzymes in fruit juices has a negative impact on nutrients and sensorial properties. The loss of ascorbic acid during a heat treatment has been an especial concern in orange juice production. Some combination methods using mild heat and other physical treatments have been explored to minimize the negative effects of intensive heat treatment. MTS utilizing ultrasound in combination with moderate heat and low pressure has been proposed in recent years as an alternative to heat pasteurization for the inactivatiation of pathogens and enzymes with minimal quality deterioration. The objectives of this work were to evaluate the effect of MTS on the quality of orange juice during storage and to compare quality of MTS treated orange juice with that of thermal pasteurized counterpart.

MTS treatment of orange juice was performed at 70oC and 200 kPa for 1 min. Unpasteurized, commercially pasteurized, and the MTS-treated orange juice were respectively stored at 4oC. The concentration of ascorbic acid, cloud stability (%T), and pectinmethylesterase (PME) activity were measured during storage. The initial residual PME activity (%) of MTS treated orange juice was slightly higher than that of thermal pasteurized juice, but the residual PME activity of both orange juices was not changed during storage. The thermal pasteurized and MTS treated orange juices retained very low values in cloud stability (%T). The day-0 ascorbic acid concentration in MTS treated samples was a little lower compared to that in raw and thermal pasteurized orange juice. However, MTS treated orange juice showed much slower degradation in ascorbic acid concentration during storage. The results suggest that MTS treatment has the potential to be used as an alternative to conventional thermal pasteurization of orange juice with better retention of juice quality attributes.