The optimisation of the colour analysis of microwave-dried tomatoes applying the Taguchi technique

Abstract

Food processors and consumers frequently worry about the inconsistent colour of dried tomatoes. To minimize detrimental color changes, process parameters need to be optimized. Thus, digital imaging with the Photoshop software and optimization with the Taguchi technique were explored to determine the surface color of microwave-dried tomato slices. The tomato sample was pretreated with water blanching (WB), ascorbic acid (AA) and sodium metabisulphite (SB). In addition, the sample was cut into 4-mm, 6-mm and 8-mm thicknesses and dried at 90W, 180W and 360W microwave power levels following the Taguchi experimental design. Color characteristics (L*, a*, b*, change in color, browning index, hue, and chroma) of the dried tomato slices were determined. The L*, a*, and b* values of fresh tomatoes were 56.73, 44.51, and 38.38, respectively. The optimum processing conditions for the color characteristics varied significantly (p< 0.05). Pretreatment is the prime significant processing parameter controlling the L*, b*, ?E, BI, and hue values. At the same time, the slice thickness considerably influenced the a* value, the ratio of a*/b* and chroma values. The digital imaging color measurements of dried tomato slices provide a suitable method for non-destructive color analysis. The ability to upgrade and modify tomato processors so they can accommodate bulk color characteristics will be made possible by this knowledge.