Abstract

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.

Abbreviation

A, Constant; B, constant; Bi, Biot number (dimensionless); c,parameter in linear function; D, moisture diffusivity (m²/s); Fo, Fourier number (dimensionless); G, lag factor (dimensionless); K, drying constant (1/s); k, moisture transfer coefficient (m/s); L, characteristic dimension, slab half thickness (m); μ,root of the transcendental characteristic equation; R², correlation coefficient; RH,relative humidity; RMSE, root mean square error; S, drying coefficient (1/s); t,drying time (s); T, air temperature (°C); Y, dimensionless moisture content; X,moisture content (kg/kg, dry basis); Exp, experimental; I, initial; 1, first characteristic value.