Characteristics of pH, Total Acid, Total Soluble Solid on Tomato Juice by Ohmic Heating Technology

Abstract

Tomatoes ( Solanum lycopersicum L.) are important vegetables all over the world and are consumed in both fresh and processed form. Tomatoes as food can be processed into tomato juice by using Ohmic heating technology. The ohmic heating technology in food processing is essentially a process in which liquid food, solids, or mixtures between the mare simultaneously heated by passing an electric current through it. Foods passed by an electric current give a response in the form of heat generation internally on foodstuffs due to the electrical resistance. This study aims to determine changes in pH, total acid, total soluble solids in tomato juice which heated at 70°C, 90°C and 110°C and duration time of heating; 15minutes, 30minutes and 45 minutes. The results showed that the temperature and duration of ohmic heating significantly affect the change of pH value and total tomato juice. The total acid value decreases as well as the lower the pH by the longer the heating. While total soluble solids are increasing by the higher temperature and heating time.