Effects of Air Velocity, Air Temperature, and Berry Diameter on Wild Blueberry Drying

Abstract:

In order to design, manufacture, and commission a commercial dryer to dry individually quick frozen (IQF) wild blueberries (Vaccinium angustifolium), The Nova Scotian Fruit Company completed a series of experiments to characterize the effect of air velocity, air temperature, and packed bed depth on drying. Based on previous experience with forced air packed bed drying systems at air temperatures up to 65°C, the experiments focused on measuring the effect of air temperature and velocity during the first few hours of drying. The data collected suggest that drying occurs solely in the falling rate period. These data were used to successfully design, build, and commission a commercial dryer with a tenfold increase in production capacity over previous equipment.

Keywords:

• Drying
• Moisture content
• Nonosmotic drying
• Temperature
• Wild blueberries
• Yield

ACKNOWLEDGMENTS

The assistance and support of Mr. L. Wilmot, Oxford Frozen Foods, and Mr. S. Roberston, ABCO, are gratefully acknowledged.

Notes

¹When the dryer was finally commissioned and drying cranberries, each packed bed required a cover in order that the dried cranberries were retained. Failure to cover the tray resulted in the dried pieces being blown out of the tray, onto the dryer floor, and thus discarded.

²As the amount of juice ranged from 7 to 15% of the total mass charge, the floors of both the pilot and commercial plants were built with a slope to capture the blueberry juice for sale.