Cactus Pear Mucilage (Opuntia spp.) as a Novel Functional Biopolymer: Mucilage Extraction, Rheology and Biofilm Development

Abstract

The investigation of novel, natural polymers has gained considerably more exposure for their desirable, often specific, functional properties. Multiple researchers have explored these biopolymers to determine their potential to address many food processing, packaging and environmental concerns. Mucilage from the cactus pear (Opuntia ficus-indica) is one such biopolymer that has been identified as possessing a functional potential that can be used in an attempt to enhance food properties and reduce the usage of non-biodegradable, petroleum-based packaging in the food industry. However, variations in the structural composition of mucilage and the different extraction methods that have been reported by researchers have considerably impacted mucilage's functional potential. Although not comparable, these factors have been investigated, with a specific focus on mucilage applications. The natural ability of mucilage to bind water, alter the rheology of a food system and develop biofilms are considered the major applications of mucilage's functional properties. Due to the variations that have been reported in mucilage's chemical composition, specifically concerning the proportions of uronic acids, mucilage's rheological and biofilm properties are influenced differently by changes in pH and a cross-linker. Exploring the factors influencing mucilage's chemical composition, while co-currently discussing mucilage functional applications, will prove valuable when evaluating mucilage's potential to be considered for future commercial applications. This review article, therefore, discusses and highlights the key factors responsible for mucilage's specific functional potential, while exploring important potential food processing and packaging applications.

Keywords: Opuntia ficus-indica; biofilms; biopolymer; cactus pear mucilage; functional properties; mucilage extraction; rheology.

Figure 1

A proposed schematic representation of the mucilage structure of Opuntia ficus-indica displaying the charged main linear chain of D-galacturonic acid and L-rhamnose units together with side chains attached to the L-rhamnose residues [21].

Figure 2

Differences in methods proposed by Goycoolea and Cárdenas [15] to extract and isolate both the gelling fraction (GE) and non-gelling (NE) mucilage/pectin fraction from Opuntia spp. cladodes.