Blackberry juice can be extracted either from fresh or frozen. Frozen berries may be cold pressed because freezing plays the part heating in breaking down the mucilaginous components.
Pressing of the fruit to extract juice is done in either hydraulic or mechanical horizontal basket presses.
For hot processing, clean, ripe, wholesome berries are heated and agitated in a steam-jacketed between 60 to 82 °C. When this temperature range is reached, the crushed berries can be pressed in a hydraulic rack and cloth press.
Heat treatment before pressing increase the yield, aroma and favor of the fruit.
Thermal treatment are usually used together with pretreatment of the fruit with pectolytic enzymes. This depectinization causes the releases of more juice through breakdown of cell wall.
The juices from blackberries contain high amounts of pectin making the juices viscous, an enzymatic depectinization is necessary in the production of clear juices and concentrates.
Around 50-100 ppm of pectinase is typically added for this purpose and juice recovery with use of these enzymes is typically in the 85-95% range.
Pectinase will improve juice and color extraction while retaining the organoleptic properties of the fruit.
The berries contain anthocyanins and a small amount do other flavonoids. The colored berries are generally very good sources of anthocyanins and processing techniques are being developed to release more of these from the skin during juice processing.
Blackberry juice can be fermented into a wine. Blackberry juice was sometimes used to color grape wine in Europe.
Blackberry juice processing
