Changes in physicochemical properties and bioactive compounds of tomato pulp submitted to different processing techniques

Tomato is a vegetable/fruit highly consumed all other the world. This study was to assess the effect of some postharvest processing such as thermal treatment, microwave, ultrasound and ultrasound combined with heat treatment on some physicochemical characteristics as well as nutrients content of tomato pulp during storage at room temperature. Results showed that the pulp samples submitted to ultrasonic and microwave treatments gave an increase in water content (95.65 to 96.75%) and total acidity (0.70 to 1.16% citric acid equivalent) and a decrease in pH (4.02 to 3.59) and brix degree (4.93 to 4.02% Brix) during the first 15 days of storage. Ultrasound treatment associated with heat treatment did not affect the physicochemical characteristics of tomato pulp and the β-carotene, but slightly reduced the total phenolic content during the first 15 days of storage (723.98 to 659.66 mg GAE/100 g DM). A significant increase in the total phenolic content (647.33 to 832.78 mg GAE/100 g DM) and β-carotene (10.77 to 12.90 mg GAE/100 g DM) was observed during storage of pulp samples treated with ultrasound and microwaves. This study showed that the ultrasound treatment associated with heat treatment can be recommended to processors for nutrients preservation during storage.   Key words: Tomato pulp, s-carotene, total phenolic, physicochemical characteristics, ultrasound, heat.