İZLİ, Nazmi Uludağ Üniversitesi, Görükle Kampüsü - Ziraat Fakültesi - Biyosistem Mühendisliği Bölümü, Turkey , POLAT, Ahmet Uludağ Üniversitesi, Görükle Kampüsü - Ziraat Fakültesi - Biyosistem Mühendisliği Bölümü, Turkey

Effect of Freeze Drying Method on Drying Characteristics, Colour, Microstructure and Rehydration Properties of Ginger

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In this study, the effects of freeze drying method on the drying characteristics, colour microstructure and rehydration properties of ginger samples were investigated. The experimental results indicated that drying rate decreases both increasing with drying time and decreasing moisture content. To select the best thin-layer drying models for the drying treatments, 10 mathematical models were fitted to the experimental data. Based on evaluation by statistical tests, the Page model having lowest reduced chi-squared (χ^2) and root mean square error (RMSE) values as well as the highest coefficient of determination (R^2) was found to be the best model for describing the drying behavior of ginger samples. All colour parameters of fresh ginger were affected by freeze drying treatment. Dried samples did not brown and the lightness (L*) and greenness (-a*) values increased while and yellowness (b*), Chroma (C) and Hue angle (α) parameters decreased. Microstructure changes of fresh and dried gingers were observed by light microscope and scanning electron microscope, respectively. Scanning electron microscopy images revealed that freeze dried samples had porous and uniform structure and the starch grains were well preserved. Freeze dried ginger samples had the highest rehydration ratio value of 5.20.

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Colour , Freeze drying, Ginger, Modeling, Scanning electron microscopy

Journal Of Agricultural Faculty Of Gaziosmanpasa University

136