Mathematical modeling of the kinetics of strawberry pulp convective drying and the effect of ascorbic acid on strawberry pulp color preservation

The five most widely used mathematical models, which were additionally extended with a dimensionless coefficient (i.e. the drying air temperature), were examined for the best approximation of strawberry pulp convective drying in a thin stagnant layer. Furthermore, the effects of the drying air temperature and ascorbic acid on changes in the color of strawberry pulp during the drying process were examined. The statistical parameters of the mathematical models (namely R, X2 , RMSE) indicated that the Extended Modified Page model had the best fit for the convective drying of strawberry pulp. The changes in the color of the dried control sample, without the addition of ascorbic acid, were ΔE = 22.95 and ΔE = 25.71 at air temperatures of 45 °C and 65 °C, respectively. The greatest change in the sample color (ΔE = 14.66) was observed at an air temperature of 45 °C and an ascorbic acid additive value of 0.5 %. However, the smallest change in the sample color (ΔE = 12.57) was observed at an air temperature of 65 °C with the addition of 1 % ascorbic acid.