Optimisation of Microwave Drying of Tomatoes (Solanum lycopersicum L.) Slices Using Taguchi Method

Abstract

The effect of the processing parameters on the microwave drying of tomatoes was investigated and the process was optimized by using Taguchi technique. Pretreatments (water blanching (WAB), ascorbic acid (ASA) and sodium metabisulphite (SMB)), slice thickness (4 mm, 6 mm and 8 mm) and microwave power level (90W, 180W and 360W) were the parameters used in the study. The increase in microwave power accelerated the drying process, thus shortening the drying time. The drying rate curves indicated the absence of a constant-rate drying rate period in the entire drying process combinations under study. It was found that the pretreatment with SMB along with 4 mm thick tomato slice and 360 W for microwave oven drying were the best processing combination within the experimental domain considered in the present study. Thus, this is the best level that can guarantee minimum drying time and time of exposure of the samples to drying microwave power thereby retaining the qualities of the dried tomatoes. The results found in this study can be applied to industrial designs and operational guides for the microwave drying of tomato slices.

Keywords: Optimisation, microwave drying, drying kinetics, tomatoes, Taguchi technique.