Antioxidant properties of tomato juice as affected by heating

The changes in the overall antioxidant properties of tomato juice samples a nd model solutions as a consequence of heat treatments were studied. The an tioxidant properties were evaluated both through the measurement of the cha in breaking and the oxygen scavenging activities. While a decrease in the a ntioxidant potential was found for short heat treatments, a recovery of the se properties was measured by prolonging heating times. Results suggested t hat the initial reduction in the overall antioxidant activity can be attrib uted not only to the thermal degradation of naturally occurring antioxidant s but also to the formation of early Maillard reaction products (MRP) with prooxidant properties. The gain in antioxidant activity coincided with the formation of brown MRP. (C) 1999 Society of Chemical Industry.