Effect on firmness of canned peeled tomatoes dipped in calcium solution at neutral pH

The consistency of peeled tomato was increased by an experimental procedure consisting of immersion of tomatoes in a bath containing a solution of calcium ions at pH 7.5. The calcium ion concentration was in the range of 400-800 mg l(-1) and the time of immersion spanned from 4 to 12 min. The samples were compared with those obtained by direct calcium addition in the range of 100-1000 mg/kg of product (tomato and juice). The results showed that samples immersed in the calcifying bath contained less calcium than those having the same consistency but obtained by direct calcium addition. The best result was obtained by treating the peeled tomatoes in a calcifying bath at calcium ion concentration of 800 mg l(-1) for times between 8-12 min. After this treatment, the product consistency was found to increase of about 90% with respect to the untreated product.