Effective moisture diffusivity of pomegranate arils under going microwave-vacuum drying

•Diffusivity increases with increase in microwave power or sample mass decreases.•Diffusivity increases with decrease in moisture content.•Polynomial models were best fitted to relate diffusivity with process parameters.

Drying of pomegranate arils was done using microwave-vacuum technique, using microwave power of 25 to 95 W, vacuum pressure of 25 to 195 mm Hg and sample mass of 65 to 235 g. The effective moisture diffusivity varied from 5.18 × 10−11 to 6.58 × 10−10 m2/s. Effective moisture diffusivity (Deff) values were found to increase as microwave power increases or sample mass decreases for constant values of remaining variables while vacuum pressure had negligible effect. A third order polynomial relationship was found to correlate the effective moisture diffusivity (Deff) with moisture content. Multivariate polynomial models were also developed for estimating the effective moisture diffusivity as a function of the microwave-vacuum drying process parameters.