The use of enzymes in fruit juice processing

As fruit becomes softer, less acidic and sweeter and heads towards its optimum state of maturity, such changes need to be taken into account by the juice processor. Apples, in particular, ate best processed prior to their fully ripened state, as solubilised pectin and softened fruit tissues will seriously affect the 

CHEMISTRY AND TECHNOLOGY OF SOFT DRINKS AND FRUIT JUICES 

Where the juice is destined for concentration it is essential for the pectin to be destroyed, or degraded, as already mentioned. Pectinase or poly(l,4-a-D-galacturonide) glycanohydrolase, in its commercially available form, is produced from fungal sources (i.e. Aspergillus sp., Rhizopus sp.). and possesses a wide variety of component activities. It operates comfortably between pH 2.5 and 6.0 and subject to supplier type can function well at specified temperatures between 30 and 60°C. Activities include 

Amylases. In the case of pome fruits other enzyme activities are sometimes required. When fruit has been picked before maturity and then ripened under controlled atmospheric conditions in a cool store, there is a likelihood of starch retention originating from the unripe fruit. This starch can become gelatinised during juice processing and can give rise to precipitation and haze effects in the final product. Amylases are used here to break down any residual starch and overcome such problems. 

Cellulases. These enzymes may be used to facilitate the rapid removal of colour during fruit processing. Such enzymes have also been employed to good effect in recent years in the total liquefaction of plant tissues during processing, obviating the need to use a press, yet increasing yields. 

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