**6. Pectinases in the wine industry**

206 Food Industrial Processes – Methods and Equipment

However, if a clear juice is required, these suspended particles have to be withdrawn. In order to do this a treatment with mixtures of commercial enzymes is carried out containing pectinases, cellulases and hemicellulases. Finally, the fluid is centrifuged to obtain the clear juice (Grassin & Fauquembergue, 1996; Kashyap et al., 2001). Although it has been noted that the proper clarification of apple juice requires mixtures of polygalacturonase and pectin methyl esterase (Yamaski et al., 1964), subsequent studies have shown that it can be clarified

In the case of orange juice, where natural pectin esterases are present, pectin is only partially methylated. Polygalacturonases are the pectic enzymes which are most commonly used and

In the process of orange juice extraction, pectinases can be added at the end of the pulp wash extraction to reduce viscosity or, preferably, at the end of the first finisher. This leads to higher yield in juice, a better extraction of soluble solids and to a lower viscosity. The action of these enzymes just reduces the viscosity without attacking the insoluble pectin that maintains the stability of the cloud. Enzyme preparations should lack or have the least possible amount of pectin methyl esterases to avoid the clarification of the product. It has been suggested that the best enzyme might be pure pectin lyase (Kashyap et al., 2001;

The enzymatic maceration of plant tissues allows the transformation of these organized tissues in suspensions of intact cells that constitute the pulpy products that are used as a basis for preparing juices, nectars, baby food and some dairy products such as yoghurts. Enzyme preparations for this purpose contain cellulases, hemicellulases and pectic enzymes which should only act on the middle lamella of the plant tissue (Kashyap et al., 2001).

Vegetable oils of olive, sunflower, coconut, palm or canola are obtained by extraction with organic solvents such as hexane. The use of pectolytic enzymes, in this case preferably alkaline, allows the extraction of vegetable oils in an aqueous process. Enzyme preparations based on cellulases, hemicellulases and pectinases have been used successfully in the extraction of olive oil. The enzyme treatment not only improves oil yield and stability but also increases polyphenols and vitamin E content enhanzing its organoleptic quality

Traditionally, fermentation of coffee is made with pectolytic microorganisms in order to remove the layer of mucilage from the coffee beans. With the same purpose, commercial enzyme preparations containing pectinase is sprayed onto the beans to ferment. A cheaper alternative is to use, with the same purpose, the filtrate of inoculated fermentations. The enzyme treatment significantly reduces the fermentation time (Amorim & Amorim, 1977; Kashyap et al., 2001; Serrat et al., 2002; Silva et al., 2000). Cocoa fermentation is essential to develop the chocolate flavour. This fermentation is carried out by a succession of different microorganisms, some of them pectolytic. Pectic enzymes allow the degradation of the cocoa

(Hoondal et al., 2002; Iconomou et al., 2010; Kashyap et al., 2001; West, 1996).

by only using a pure pectin lyase (Ishii & Vokotsuka, 1973).

**5.1.2 Cloudy juices (i.e., citrus, tomato, nectars)** 

of great interest for this type of fruit juice.

**5.2 Maceration products of plant tissues** 

**5.3 Extraction of vegetable oil** 

**5.4 Coffee, cocoa and tea fermentation** 

Rebeck, 1990).

Wine is the result of the fermentation of grape juice. Pectinases are the most important enzymes used by the winemaking industry although commercial preparations may contain other enzymatic activities such as hemicellulases, glucanases and glycosidases (Rombouts & Pilnik, 1980).

Pectic enzymes are synthesized naturally by the plant and are present in the grape. However, they have low activity during the wine producing process (Ducasse et al., 2011). Microbial pectolytic enzymes especially of fungal origin are resistant to the conditions of fermentation and can be used to facilitate processes, improve quality and diversify products. So far, commercial enzymes are produced all from fungi, mainly of the genus *Aspergillus*. Although all enzymes are produced by *Aspergillus*, pectinase preparations currently available for the wine market are very different. Both the type of activities as well as their concentration in the preparations depend on the strain of *Aspergillus* used, the fermentation conditions for production, the nature of the fermented substrate and the degree of partial purification.

Various research studies have shown that the addition of pectolytic enzymes leads to increased levels of methanol in wine (Revilla & González-SanJosé, 1998; Servili et al., 1992) due to the activity of pectin methyl esterase. Methanol is toxic and its maximum concentration in wine is regulated. Therefore, pectin methyl esterase activity should be at low concentrations in commercial mixtures.

The functions of pectic enzymes in the winemaking process are to support the extraction process, maximize juice yield, facilitate filtration and intensify the flavour and colour.
