Acceptability and antioxidant properties of a semi-dried and smoked tomato product

Abstract

Tomatoes (Lycopersicon esculentum) are good sources of antioxidants, such as lycopene, which have been shown to be beneficial for health. Careful drying of tomatoes can concentrate antioxidants and provide a tasty food product that can help to reduce the incidence of cancers and cardiovascular diseases. Semi-drying to a final dry matter content of 20% at 40°C followed by smoking was used to produce a new tomato product. Colour, pH, titratable acidity and lycopene, vitamin C and total phenol content and antioxidant activity of two tomato cultivars (Caluna and Toronto) were determined on fresh, dried or smoked samples and on final products made from the two different cultivars. The pH of the fresh and final products were very similar (overall mean 4.43±0.02) while the titratable acidity of the final product increased to a mean of 1.24% citric acid compared to the fresh tissue mean of 0.47% citric acid. The drying process increased the extracted lycopene content from a mean of 94.4 mg/100 g DM in the fresh tomatoes to 126.4 mg/100 g DM in the semi-dried tomatoes. In contrast, the total phenols were reduced from a mean of 255 mg GAE/100 g DM in the fresh tomatoes to a mean of 214 mg GAE/100 g DM in the semi-dried tomatoes. The mean vitamin C content of the fresh tissue was 313 mg/100 g DM with 32 mg/100 g DM retained in the dried tissue. The overall mean antioxidant capacity of the dried product was increased by the drying and processing treatments to a mean of 2373 ABTS (μM Trolox/100 g DM). Measurement of the colour of the dried products showed the typical red colour of the tomatoes was retained during processing. Panellists evaluated three tomato products made from the cultivars Caluna and Toronto for appearance, colour, taste and overall acceptance. In contrast to many commercial products, the colour of the new tomato products was similar to the original fresh tomatoes. Panellists preferred the dried and smoked Toronto product sprayed with white vinegar. A new smoked tomato product containing health promoting antioxidants was produced.