Spray-drying of fruit and vegetable juices: Effect of drying conditions on the product yield and physical properties

Spray-drying is one of the highly utilized techniques to increase the shelf-life of food products. However, there are problems during spray-drying of sugar-rich fruit and vegetable juices due to the low glass transition temperature of sugars present in these products (Bhandari, Datta, & Howes, 1997). The sugars transform into a sticky form which increases the deposition at the surface of the drying chamber, which eventually decreases product yield. To achieve an effective drying and to obtain an acceptable product, drying conditions must be optimized. Product yield and physical properties of the final powder are affected by various factors, including carrier material and its concentration added into the feed, feed flow rate, atomization speed/pressure, and drying temperature. This paper reviews the effects of these conditions on yield and the physical properties of the final product. Recent studies have clearly shown that milk-based protein isolates as carrier materials are more effective, according to product yield in lower ratios, than carbohydrate-based carrier materials. Physical characteristics of the final powder vary according to process parameters.