Effect of Drying Methods and Pretreatment on some Physicochemical Quality Attributes of Tomato Powder

The effect of sun and oven drying methods and pretreatment on the physicochemical quality attributes of tomatoes powder was investigated. Twenty five kilograms of fresh tomatoes were sorted, washed and the initial physicochemical properties determined. The samples were divided into samples A, B, C and D. Sample A (dipped in 1% metasulphite and sundried), sample B (dipped in 1% metasulphite and oven dried), sample C (unsulphited sundried) and sample D (unsulphited oven dried) were taken as dried when the weights remains constant at three consecutive readings. The physicochemical properties of tomato powder were determined using standard methods and data collected were analyzed statistically. Results showed that drying and pretreatment has no significant effect (p< 0.05) on the total sugar content of tomatoes. The method of drying used and pretreatment resulted in significant increases in the ash, crude fiber and mineral content while the moisture and pH of tomatoes decreased significantly after drying. The sundried tomato powdered had the highest increase in mineral content. It is therefore recommended that sun drying method without the use of pretreatment should be used for tomato drying in terms of retained physicochemical quality attributes in cases where spray dryers are unavailable.