Use of ultrasound pre-treatment before microwave drying of kiwifruits – an optimization approach with response surface methodology

Abstract
In the present study, the thermal properties (drying time, effective moisture diffusion (Deff), specific energy consumption (SEC)) and quality (colour and shrinkage) of kiwi slices were optimized using the response surface methodology (RSM). The optimization process was done using central composite design (CCD) in Design Expert software with three independent variables including microwave power (100, 200, and 300W), sample thickness (4, 6, and 8mm) and ultrasound pretreatment time (10, 20, and 30 min). The results showed that by increasing the microwave power and ultrasound pretreatment time and decreasing the thickness, the SEC and drying time decreased in quadratic form, while the Deff linearly increased. Moreover, decreasing microwave power and sample thickness as well as increasing the treatment time diminished the shrinkage and colour. The obtained optimal results (4 mm thickness, ultrasound for 30 min, 257.2 W of microwave power) were: drying time for 13.779 min, Deff equal 6.67x10-9 m2/s, SEC equal 6.343 MJ/kg, the total colour difference of 17.94, and shrinkage of 46%.

Author
Mohammad Kaveh

DOI
https://doi.org/10.1111/jfpp.16714

Publisher
Journal of Food Processing and Preservation

ISSN
1745-4549

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