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EXPERIMENTAL ANALYSIS OF MICROWAVE DRYING KINETICS AND CHARACTERIZATION OF GINGER RHIZOMES
Author(s) -
GANESAPILLAI MAHESH,
MURUGAN PULIKESI,
SINGH ARUNA
Publication year - 2012
Publication title -
journal of food processing and preservation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.511
H-Index - 48
eISSN - 1745-4549
pISSN - 0145-8892
DOI - 10.1111/j.1745-4549.2011.00577.x
Subject(s) - rhizome , microwave , thermal diffusivity , arrhenius equation , dehydration , materials science , diffusion , chemistry , moisture , biological system , mathematics , analytical chemistry (journal) , chromatography , activation energy , thermodynamics , composite material , botany , organic chemistry , computer science , physics , telecommunications , biochemistry , biology
Ginger rhizomes of different thickness, microwave output power and sample load were dehydrated in a modified microwave oven, and effective moisture diffusivity was calculated. Among the various basic models considered, diffusion equation was most suitable to predict the drying behavior for the process conditions. Based on the interpretations, the constants and coefficients were rewritten in Arrhenius and logarithmic expressions for microwave power. The derived mathematical models were validated according to statistical parameters, viz. reduced chi‐square, root mean square error, mean bias error and t ‐test values. The modified diffusion model explained the suitability of thin layer microwave drying behavior of ginger rhizome slices, yielding the highest R 2 of 0.9983. The effect of microwave drying on extraction of oleoresins with hexane as the solvent was in the range of 2.53–4.55%. Scanning electron microscopy and Fourier transform infrared spectroscopy revealed enhanced integrity of texture and functional groups by microwave treatment. PRACTICAL APPLICATIONS Drying, a process of removal of moisture content, was carried out on ginger rhizomes. Besides several advantages during dehydration, some important changes take place, such as structural and physicochemical modifications, which affects the final product quality. Microwave heating at specific experimental conditions was aimed at the restoration of nutritional and medicinal properties of the raw material. Mathematical models applied in this research will be helpful to analyze, simulate as well as to design and scale up the microwave drying process for industrial and commercial applications. Furthermore, the product may have an increased shelf life, finished product quality; may reduced energy cost in comparison with the conventionally dried rhizomes; and may serve as ingredient for medicinal, pharmaceutical and cosmetics industry for the extraction of essential oils such as oleoresins.