Drying dynamics of differently prepared fresh cranberries and blueberries using IR drying

Cranberries (Oxycoccus palustris) and blueberries (Vaccinium corymbosum) are berries rich in polyphenols known to promote health in various ways as a diuretic, to prevent cancer, to improve the function of the cardiovascular system and digestive tract. Containing a relatively large amount of vitamin C, they can significantly enhance the effects of antibiotics. One method of long-term preservation is to dry them. Drying conditions also have a significant effect on product quality. As the berry skin inhibits the removal of moisture, it is necessary to find a simple and convenient way to prepare the berries to speed up the drying process in low-heated air. An IR beam dryer with a drying temperature of 41 °C was chosen as an experimental device. The moisture output of whole berries and needled pierced berries was compared. The results of the experiment showed that the moisture removal of whole berries is linear, which means that the skin of the berries plays an important role. The slope was k = 17.7·10-3 (change in weight (g) in relation to drying time (min)). The pierced cranberries showed an exponential dynamics of moisture removal. This means that the holes in the casing play a very important role in drying the berries faster. After 22 hours of drying, moisture from pierced cranberries was removed almost 3 times more than from whole berries (64.4% vs. 26.5%). Blueberries have a similar situation, but they dry faster because their skin is thinner.