Thermal processing causes a number of undesirable changes in physicochemical and bioactive properties of tomato products. Microwave (MW) technology is an emergent thermal industrial process that offers a rapid and uniform heating, high energy efficiency, and high overall quality of the final product. The main quality changes of tomato puree after a pasteurization at 96 ± 2 °C for 35 s, provided by a semi industrial continuous microwave oven (MWP) under different doses (low power/long time to high power/short time) or by conventional method (CP) were studied.
The results showed that all heat treatments reduced color quality, total antioxidant capacity and vitamin C, with a greater reduction in CP than in MWP. On the other hand, use of a MWP, in particular, high power/short time (1900 W/180 s, 2700 W/160 s and 3150 W/150 s) enhanced the viscosity, lycopene extraction and decreased the enzyme residual activity better than with CP samples. For tomato puree, polygalacturonase was the more thermos resistant enzyme, and could be used as an indicator of pasteurization efficiency.
MWP was an excellent pasteurization technique that provided tomato puree with improved nutritional quality, reducing process times compared to the standard pasteurization process.
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