Enzymatic Extraction of Pectin from Opuntia ficus-indica Cladodes

Within studies about valorisation of agricultural and agro-industrial wastes, in the past the authors have worked on the extraction of mucilage and pectin from cladodes of prickly pear cultivated in Sicily. Mucilage and pectin are hydrocolloids of considerable commercial interest, as gelling, emulsifiers and thickening agents and are used mainly in the food, pharmaceutical and cosmetics industries. Mucilage and pectin, from the structural point of view, are complex polysaccharides consisting of arabinose, xylose, galactose, glucose and uronic acids, in different percentages, with the pectin richest in the latter. In the earlier works the mucilage was extracted with cold water acidulated, while the pectin with dilute acid at 90° C, both were recovered by precipitation with ethanol. This paper proposes an interesting variation, namely the extraction of pectin with commercial pectinolytic enzyme, after that of the mucilage with the classic method. The experimental tests conducted on different types of cladodes have given extraction yields of pectin between 6.12 and 7.08 %, comparable to those obtained with the classical method with acid (6.20–7.20 %). However, the enzymatic extraction allows obtaining undoubted ecological and economic advantages: lower extraction temperature and easier treatment of purification of the effluents. This could be one more reason for the emergence of companies that work cladodes of pruning. Alternatively, the existing pectin industries could use such cladodes as raw material, in addition to the lemon peel traditionally worked. Of course, it is necessary to characterize in deep the pectin from cladodes to assess its quality.