Development of an imaging system for spatially real-time measurement of drying parameters in industrial drying units

Abstract

Lack of accurate information for the drying kinetics is the main barrier to optimize drying processes effectively. Online monitoring of drying data is not common due to practical issues involved in set-up application. In this study an imaging system was developed for large drying units to investigate the quality changes (color kinetics and shrinkage) combine with weight loss of food product spatially and non-destructively during convective drying. The imaging setup was used in a diagonal-airflow batch dryer and shifted along the dryer length to take data (food images and weight loss) at different positions using potato slices (5mm thick, 60°C) as drying material. First order model fitted well to value of ∆L^*and ∆b^* while ∆a^* and ∆E fitted in zero order model. The experimental and models predicted color kinetics revealed good correlation coefficients (R² = 0.88-0.99, P ˂ 0.0001). The shrinkage of the samples exhibited two periods; a faster with MR up to X/X_o ≥ 0.3 and afterwards it became slow employing polynomial cubic regression (R² = 0.97-0.99, P ˂ 0.0001). The imaging system effectively measured the change in quality parameters spatially along the dryer. The current study would help to develop and implement low cost setup for online measurements used for the assessment of drying processes in large drying units.