Technological and Chemical Studies on Canned Tomato Product

Abstract

In this study the effects of pre-treatments additives (citric acid 2%, NaCl 2%, and CaCl2 1%), during processing and storage periods on chemical composition, phytochemical compounds, antioxidant activity, total counts (bacteria, yeast and molds) and sensory evaluation of fresh canning tomatoes was investigated. The fresh tomatoes had moisture content (94.1%), pH (4.54), total acidity (0.48%), ash (23.1%), fibers (22.5%), total and reducing sugars were 53.7 and 7,8%, respectively. Fresh tomatoes were rich in antioxidant compounds (Lycopene, total carotenoids, ascorbic acid and total phenols) which represent 109,162.1, 433.4 and 836.3 mg/100 g dry weight basis, respectively, meanwhile antioxidant activity for fresh 39.4% (FW). Moisture content of tomatoes after canning process is no more change compared to fresh tomatoes, since it was about 94% of control sample at zero time. Even, after storage expected at 4 and 8 months which reached about 93.98% and 93.97%, respectively. The average of pH and titratable acidity at zero time 4.44 and 0.53% of control sample, were slightly decreased after 4 and 8 months. The ash and fibers content of canned tomatoes were reduced compared with fresh tomatoes, while total and reducing sugar content increased after canning process compared to fresh tomatoes and was decreased after 4 and 8 months of storage. On the other hand, non-enzymatic browning in canned tomatoes was increased when compared to fresh tomatoes. Although, canned tomatoes product was high acceptability and safety for consumer as a result of removal of seeds and peel. However, it had low nutritional values when compared with fresh tomatoes. Because of reduction of antioxidants active compounds such as lycopene, total carotenoid, ascorbic acid, and total phenols. Canned tomatoes had reduction in antioxidant activities compared with fresh tomatoes, since reached to 34.2% after canning process. In the same time, antioxidant activities were reduced from 33.7% to 33.1% after 4 and 8 months of storage. In addition, most of antioxidant compounds were stabled during storage especially total phenols and lycopene. Canning of tomatoes and pre-treatments can extend their shelf life and improved acceptability and safety of this product. CaCl2 pre-treated (T4) had the best results compared with control (T1) and the other treatments. The total count of bacteria, yeast and molds for control and treatments less than permissible limits (103/g and 104/g) and the values of sensory evaluation of canned tomato product were high. It can be recommended that the canning process uses to increase the shelf life of tomatoes because the excess of Egyptian total production is very high after using as fresh fruit.