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Design and operation of a microwave oven with rotating drums

Cilvez, Eda
In this study it was aimed to design and operate a new system with sufficient number of rotating drums since rotation of turntable is incapable of providing uniformity. Effect of new design on final color values and moisture content were also investigated. Macaroni beads were colored with CoCl2 solution and processed in a domestic microwave oven starting from 11.3±0.10% moisture content and L*= 41.1±0.31 , a*= 8.5±0.27 , b*= 5.3±0.22 color value with turntable and the proposed design. In experiments 40%, 60%, 80% and 100% power levels and 1, 2 and 3 min processing times and 2 different locations were used. The average color values measured were not affected significantly by the locations studied inside the cavity for both operation types. The changes in color values were found to be significant with altering power level for both operation types. Time also changed average color values for samples processed on turntable and in rotating drums. The new design lowered the average L* values of the final product and kept the sample from burning. Average a* and b* values were not significantly affected by the operation type. The uniformity of final product in terms of color distribution was affected significantly by the operation type and the improvement in uniformity calculated quantitatively by means of variances and found out that the new design improved the color uniformity of the final product by 94.7%. The non-uniformity of the products processed on turntable was significantly changed with power level. Time or location did not affect uniformity significantly for both operation types. The final average moisture contents of samples processed on turntable were lower than the ones processed with the new design. That is, the rotating drums lowered the moisture removal compared to the turntable.