**3. The pectinolytic enzymes**

More than a century ago, DeBary at1886 showed pectinase's importance as a virulence factor in the decomposition of pectin in the plant cell wall [21]. Then, these enzymes have been used for food processing at the domestic level at first, to use in the industrial sector in 1930. Till1960s, pectinases were practically used in fruit juice and wine for clarification [22]. Nowadays, pectinases have received attention worldwide as an eco-friendly biocatalyst that contains a 25% share in the global enzyme market for food and beverages [23, 24]. In 2016, the pectinases market reached 30.0 million \$ and was estimated to rise to 35.5 million \$ by 2021 [25]. Pectinolytic enzymes or pectinase enzymes are a group of complex enzymes that catalyze the degradation of pectin-containing substances. These enzymes account for 10% of the produced global industrial enzymes [1] and are secreted in plants, insects, Nematoda, protozoa, fungi, yeast, and bacteria [22]. Although plant and microorganisms are the major sources for pectinase enzyme generation, microbial sources (Fungi, yeast, and bacteria) have been selected to be the primary ones due to technical and commercial viability [26].

Pectinolytic enzymes have been classified according to three criteria [27, 28]:


For most enzymes, the type of cleavage is random (Endo) or terminal (Exo). The recent classification based on the action mode on pectin, preferred substrates, and products, **Table 1**, where these enzymes are classified into three types [30]:


#### *The Microbial Degradation for Pectin DOI: http://dx.doi.org/10.5772/intechopen.100247*


**Table 1.**

*Classification of pectinases enzymes [inspired from Parissa et al., 2011 [29]].*
