**13. Extraction of polyphenols and aroma compounds: improvement of sensorial characteristics**

The objective of adding commercial pectolytic preparations during red grape maceration stages is to improve the extraction of polyphenols and aroma molecules from the intracellular content of grape skin cells. The consequence of this higher yield of extraction is obtaining more structured wines, higher colour intensity, and wine aroma complexity [72]. Moreover, the resulting wine will be more easily clarified and filtered as well as the juice yield will be substantially increased. It is important to note that among the secondary activities present in commercial enological enzyme preparations, cinnamoyl esterase activities should be eliminated because they hydrolyse ester bonds of hydroxycinnamic acids, which are present in red grape skins [73], and release the free phenolic acids. These are substrates for the cinnamate decarboxylase of some *Saccharomyces cer*e*visiae* strains and of the wine spoiling yeast *Brettanomyces*. Cinnamate decarboxylase transforms the free phenolic

#### *Fungal Pectinases in Food Technology DOI: http://dx.doi.org/10.5772/intechopen.100910*

acids into volatile phenols that confer off-odours described as medicinal odour, leather or smoky to white wines, and barnyard or horsey odours to red wines [74]. Therefore, it should be made sure that no traces of cinnamoyl esterase activities are present in enzyme preparations for enological use. In addition, the pectin methylesterase activity (PE) should be negligible in the commercial enzyme preparations because no methanol should be generated when they are added [75].

The commercial enzyme preparations may also potentiate wine aroma expression by releasing volatile molecules that in their glycosylated form are not volatile, and consequently odourless. Primary or varietal aromas of wine are those whose origin are molecules of the grape cells, and they provide the characteristic aromatic profile of the grape variety used to elaborate the wine. Most of those volatile molecules appear in the grape cell as bound forms to sugars, becoming non-volatile and odourless. Glycosidic enzymes hydrolyse the linkage to the sugar residue and release the odorous molecule [76]. In addition, pectinolytic activities collaborate to break down cell walls and thus, liberate the aromatic volatile molecules.

It is important to point out that glycosidic enzymes used in enology should possess high specificity for their substrate, and β-glucosidases that hydrolyse anthocyanin glucosides should not be present in the commercial enzyme preparation because they provoke dreadful consequences of colour loss in red wines.

Finally, it should be underlined that enzymes can only extract what is already in the vegetable cells and tissues, and a good quality starting material is a requirement to obtain processed foods and beverages of premium quality. Pectinases can help to speed-up processes of extraction, maceration, clarification, filtration, and colloidal stabilisation of the processed product and thus they enhance product quality and improve the efficiency of the process, nevertheless when they are not properly used, they can spoil the final product. Additionally, pectinases can be used to upgrade food industry by-products to obtain value-added products and to produce animal feedstock. In this regard, pectinases have become a current trend in the feed industry and their use opens new perspectives for further research in the production of fungal pectinases.

### **Acknowledgements**

The authors acknowledge the support from EU project PGSYS-Exchange Project FP7-People-2012-IRSES-269211.

*Pectins - The New-Old Polysaccharides*
