Determination of shrinkage characteristics of cylindrical potato during convective drying using novel image processing technique

An experimental setup has been developed to study the drying and shrinkage characteristics of food material at different drying conditions. This setup has two unique features i.e. continuous weight measurement and continuous capturing of side and top view images of the food sample. Continuous weight measurement is required to predict the transient drying characteristics and with the help of captured images, the shrinkage characteristics can be estimated. The shrinkage characteristics include change in diameter, thickness, surface area, bulk volume and density of the potato sample. An image processing code is developed in MATLAB for processing and analysing the top and side view images. The food material experimented in this work is a potato sample cut in the shape of a cylindrical disk. It is observed that the diameter, thickness, surface area and bulk volume of the potato sample decrease with the moisture content throughout the drying process. However, the bulk density increases in the early stage of the drying process, reaches a maximum value and then decreases again. The maximum reduction in bulk volume is found to be 65.8% at air flow velocity of 4 m/s and temperature of 60 °C.