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Drying kinetics of apricot halves in a microwave-hot air hybrid oven


Drying behavior and kinetics of apricot halves were investigated in a microwave-hot air domestic hybrid oven at 120, 150 and 180 W microwave power and 50, 60 and 70 °C air temperature. Drying operation was finished when the moisture content reached to 25% (wet basis) from 77% (w.b). Increase in microwave power and air temperature increased drying rates and reduced drying time. Only falling rate period was observed in drying of apricot halves in hybrid oven. Eleven mathematical models were used for describing the drying kinetics of apricots. Modified logistic model gave the best fitting to the experimental data. The model has never been used to explain drying behavior of any kind of food materials up to now. Fick’s second law was used for determination of both effective moisture diffusivity and thermal diffusivity values. Activation energy values of dried apricots were calculated from Arrhenius equation. Those that obtained from effective moisture diffusivity, thermal diffusivity and drying rate constant values ranged from 31.10 to 39.4 kJ/mol, 29.56 to 35.19 kJ/mol, and 26.02 to 32.36 kJ/mol, respectively.

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a, b, c, g, h, l, n :

Equation constants

α :

Thermal diffusivity (m2/s)

α 0 :

Pre-exponential constant of Arrhenius equation (m2/s)


Association of official analytical chemists


Drying rate (g water/g dry matter.min)

D eff :

Effective moisture diffusivity (m2/s)

D 0 :

Pre-exponential constant of Arrhenius equation (m2/s)

E a :

Activation energy (kJ/mol)


Food and Agriculture Organization of the United Nations

k :

Drying rate constant (1/min)

k 0 :

Pre-exponential constant of Arrhenius equation (1/min)


Half thickness of sample (m)

M 0 :

Initial moisture content (g water/g dry matter)

M e :

Final moisture content (g water/g dry matter)

M t :

Moisture content at any time (g water/g dry matter)


Moisture ratio

MR exp,i :

Experimental moisture ratio

MR pre,i :

Predicted moisture ratio


Number of experimental data


Universal gas constant (kJ/mol K)



R 2 :

Correlation coefficient


Root mean square error

t :

Drying time (min)

T :

Temperature of slab at any time (°C)

T 0 :

Initial temperature of slab (°C)

T s :

Temperature of drying chamber (°C)


Dimensionless temperature ratio

x :

Independent variable

χ2 :

Reduced Chi square

W R , w :



Wet basis


Number of parameters in the model


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Ministry of Science, Industry and Technology of Republic of Turkey and Arçelik A.Ş. are acknowledged for the support of the study. E. Horuz also acknowledges TUBITAK-BIDEB (The scientific and Technological Research Council of Turkey) for the national Ph.D. study scholarship.

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Correspondence to Hüseyin Bozkurt.

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Horuz, E., Bozkurt, H., Karataş, H. et al. Drying kinetics of apricot halves in a microwave-hot air hybrid oven. Heat Mass Transfer 53, 2117–2127 (2017).

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  • Root Mean Square Error
  • Thermal Diffusivity
  • Microwave Power
  • Moisture Diffusivity
  • Effective Moisture