Computer Vision for Real-Time Measurements of Shrinkage and Color Changes in Blueberry Convective Drying

The effect of temperature on blueberry drying rate, shrinkage, and color changes was evaluated from drying experiments for both high bush (Vaccinium corymbosum L.) and wild (Vaccinium angustifolium) blueberries. Drying temperature significantly affected texture and color of both varieties. Temperatures above 55°C caused a significant color change (ΔE > 25) within 30 min of the beginning of drying, followed by a significant drop in density from 1.02 to 0.38 g/cm³. In contrast, drying at temperatures below 50°C resulted in nonsignificant color changes and an eventual density increase to 1.26 g/cm³. It follows that blueberry color could be used as an early stage indicator of quality degradation in the process of drying.