**7. Extraction of vegetable and fruit juice**

In the course of juice preparation from fresh fruits with mechanical crushing or pressing, a soluble proportion of pectic substances (water-soluble pectin) is released in the liquid phase leading to an increase of the juice viscosity. However, insoluble pectic substances remain bound to hemicellulose and cellulose fibrils by means of side chains [50]. Water is retained with pulp particles leading to hinder the flow of cell sap, which remains bound to the pulp in the form of a jellified mass. Consequently, the juice yield is low. Also, raw press juice contains insoluble pectin particles (cloudy particles) that carry surface negative charges, which can coat positively charged surface proteins forming particles that give unpleasant mouthfeeling and off-tastes for many consumers. A mixture of pectolytic enzymes with cellulase could be useful to degrade both pectin and cellulose of cell walls and middle lamella by breaking down the pectin chain and other attached polysaccharides to their mono- and oligo-monomers. As a result, a crystal-clear juice with a

good appearance, low viscosity, high stability, appropriate mouth-feeling, and taste characteristics will be obtained, in addition to the benefit of an increase in the yield. Pectinase treatments are usually performed to prepare juice from fruits containing a high percentage of pectic substances, such as apple, pear, berries, citrus, and banana [51]. A mixture of pectinases can also decrease the filtration time up to 50% [52]. However, in some cases, it is necessary to use a mixture of pectinases, cellulases, arabinases, and xylanases to increase the fruit pressing efficiency for juice extraction [53]. In this respect, Josh *et al.* [54] found that a partially purified pectinase, produced by *A. niger* in solid-state fermentation of apple pomace, could increase juice extraction from 52 to 78% in plum, 38 to 63% in peach, 60 to 72% in pear, and 50 to 80% in apricot. The advantages of pectinase addition are: increase of colour, titrable acidity, total sugars in the extracted juices, decrease of pH, Brix/acid ratio, and relative viscosity. Biochemical properties of some microbial pectinases, including those produced by bacteria, can be found in a former review [39].

Mixtures of pectinases, cellulases, and hemicellulases can be used to assist in the extraction of edible oils, thus to increase the extraction efficiency of vegetable oils. The mixture of enzymes that hydrolyze complex polysaccharides of the cell walls of oilseeds and oily fruits, liquefies the structure of cell walls, leading to the release of the sap of cells including oil and fat-soluble active molecules (e.g., α- and β-carotenes, sterols, and vitamin D) that prevent oxidation of oils.
