Effects of Variety and Drying Methods on the Nutrient Retention in Tomato (Solanum lycopersicum L.) Slices

Abstract

This study investigated the effects of variety and drying methods on nutrient retention in dried tomato slices. Four tomato varieties  (UC82B, Roma, Eva-F1 and Kerewa) were subjected to three drying methods (sun, oven and cabinet). The proximate, carotenoids,  vitamins (A, C and E), flavonoids, phenolic acid and total dietary fibre contents of the fresh and dried tomatoes were determined using  standard laboratory procedures. Percentage retention was calculated using the true retention formula. Data obtained were subjected to  multivariate analysis of variance and means separated using Duncan’s multiple range test. For fresh tomato samples; moisture, total  dietary fibre, lycopene, betacarotene, vitamins C, E, retinol equivalent vitamin A, flavonoid and phenolic acid contents ranged from  89.62-95.41%, 2.65-38.52%, 26.5-44.67 mg/kg, 1.82-3.54 mg/kg, 5.52-8.62 mg/100g, 0.16-0.23 mg/100g, 30.3-59.1 µg/100g, 5.13- 19.24  mg/100g and 22.43-31.89 mg/100g, respectively. For dried tomato slices; moisture, ash and total dietary fibre contents ranged from  5.74-9.83%, 6.70-10.94% and 18.63-38.52%, respectively. Lycopene, beta-carotene, flavonoid, phenolic, vitamins C, E and retinol equivalent  vitamin A contents ranged from 36.50-54.70 mg/kg, 2.78-4.5 mg/ kg, 13.07-70.98 mg/100g, 51.50-352.00 mg/100g, 34.35-94.46 mg/100g,  0.54-2.04 mg/100g and 46.4-75.1 µg/100g, respectively. Percentage retention of lycopene, beta carotene, flavonoids, phenolic acid and  total dietary fibre ranged from 4.23-13.48%, 4.45-16.21%, 9.76-73.11%, 8.49-57.19% and 31.40-61.64%, respectively. While it ranged from 20.59-73.81%, 9.00-72.10%, and 4.45-16.21% for vitamins C, E and A, respectively. In conclusion, the oven-dried tomato slices retained  more nutrients than the sun and cabinet-dried samples irrespective of tomato variety.