Biot number - lag factor (Bi-G) correlation for tunnel drying of baby food

To obtain mass transfer coefficients of three baby food mixtures on cereal basis in a tunnel dryer, Bi-G drying correlation can be used. Experimental moisture content values for three mixtures at three different air temperatures (60, 80 and 100°C) and air velocities (0.5, 1.0 and 1.5 m/s) during tunnel drying were collected. Effective moisture diffusivities coefficients were calculated in two ways and for mixtures 1, 2 and 3 and ranged between 1.51 × 10-8 to 52.7 × 10-8 m2/s, 1.05 × 10-8 to 64.9 × 10-8 m2/s and 0.107 × 10-8 to 53.1 × 10-8 m2/s, respectively. At lower drying temperature, moisture diffusivities values calculated in two ways agreed better than at higher temperature. The influence of baby food composition on mass transfer parameters was observed.   Key words: Baby food, exponential drying model, mass transfer coefficients, tunnel drying.