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Recent Advances in the Development of Food Enzymes
With the increase in market requirements for food packaging and preservation, the
quest for optimum performance of enzymes has given enzyme engineering, particularly enzyme/cell immobilization or cell encapsulation, prime importance in production of biocatalyst with improved properties (Cao et al. 2003; Hamilton 2009).
Immobilization
Immobilization implies associating the enzymes or cells with an insoluble matrix so
that it is retained for further economic use, i.e., giving the optimal immobilization
yield and having the activity stability in long term (Miladi et al. 2012). Over the last
few decades, intensive research in the area of enzyme technology has shown promise, i.e., the immobilization of enzymes (for extracellular enzymes) and cells (for
intracellular enzymes). Immobilization enzymes and cells are widely used in the
fermentation industry. Also biosensors are designed on the principle of immobilization of enzymes as it is convenient, economical and a time-efficient process of isolation and purification of intracellular enzymes (Mishra et al. 2016). Immobilization
can be performed by several methods, namely, entrapment/microencapsulation,
binding to a solid carrier, and cross-linking of enzyme aggregates, resulting in
carrier- free macromolecules. The latter presents an alternative to carrier-bound
enzymes, since these introduce a large portion of non-catalytic material. This can
account to about 90% to more than 99% of the total mass of the biocatalysts, resulting in low space-time yields and productivities (Sheldon 2007).
Entrapment/(micro)encapsulation, where the enzyme is contained within a given
structure. This can be: a polymer network of an organic polymer or a sol-gel; a
membrane device such as a hollow fiber or a microcapsule; or a (reverse) micelle.
Apart from the hollow fiber, the whole process of immobilization is performed insitu. The polymeric network is formed in the presence of the enzyme, leading to
supports that are often referred to as beads or capsules. Still, the latter term could
preferably be used when the core and the boundary layer(s) are made of different
materials, namely, alginate and poly-l-lysine. Although direct contact with an
adverse environment is prevented, mass transfer limitations may be relevant,
enzyme loading is relatively low, and leakage, particularly of smaller enzymes from
hydrogels (namely, alginate, gelatin), may occur. This may be minimized by previously cross-linking the enzyme with multifunctional agent (namely, glutaraldehyde)
(Brady and Jordaan 2009; de Segura et al. 2003) or by promoting cross-linkage of
the matrix after the entrapment (de Assis et al. 2004). The use of LentiKats, a
polyvinyl- alcohol-based support in lens-shaped form, has been used for several
applications in carbohydrate processing. Among these are the synthesis of oligosaccharides with dextransucrase (de Segura et al. 2003), maltodextrin hydrolysis with
glucoamylase (Rebroš et al. 2006), lactose hydrolysis with lactase (Grosová et al.
S. Farooq et al.
Recent Advances in the Development of Food Enzymes
With the increase in market requirements for food packaging and preservation, the
quest for optimum performance of enzymes has given enzyme engineering, particularly enzyme/cell immobilization or cell encapsulation, prime importance in production of biocatalyst with improved properties (Cao et al. 2003; Hamilton 2009).
Immobilization
Immobilization implies associating the enzymes or cells with an insoluble matrix so
that it is retained for further economic use, i.e., giving the optimal immobilization
yield and having the activity stability in long term (Miladi et al. 2012). Over the last
few decades, intensive research in the area of enzyme technology has shown promise, i.e., the immobilization of enzymes (for extracellular enzymes) and cells (for
intracellular enzymes). Immobilization enzymes and cells are widely used in the
fermentation industry. Also biosensors are designed on the principle of immobilization of enzymes as it is convenient, economical and a time-efficient process of isolation and purification of intracellular enzymes (Mishra et al. 2016). Immobilization
can be performed by several methods, namely, entrapment/microencapsulation,
binding to a solid carrier, and cross-linking of enzyme aggregates, resulting in
carrier- free macromolecules. The latter presents an alternative to carrier-bound
enzymes, since these introduce a large portion of non-catalytic material. This can
account to about 90% to more than 99% of the total mass of the biocatalysts, resulting in low space-time yields and productivities (Sheldon 2007).
Entrapment/(micro)encapsulation, where the enzyme is contained within a given
structure. This can be: a polymer network of an organic polymer or a sol-gel; a
membrane device such as a hollow fiber or a microcapsule; or a (reverse) micelle.
Apart from the hollow fiber, the whole process of immobilization is performed insitu. The polymeric network is formed in the presence of the enzyme, leading to
supports that are often referred to as beads or capsules. Still, the latter term could
preferably be used when the core and the boundary layer(s) are made of different
materials, namely, alginate and poly-l-lysine. Although direct contact with an
adverse environment is prevented, mass transfer limitations may be relevant,
enzyme loading is relatively low, and leakage, particularly of smaller enzymes from
hydrogels (namely, alginate, gelatin), may occur. This may be minimized by previously cross-linking the enzyme with multifunctional agent (namely, glutaraldehyde)
(Brady and Jordaan 2009; de Segura et al. 2003) or by promoting cross-linkage of
the matrix after the entrapment (de Assis et al. 2004). The use of LentiKats, a
polyvinyl- alcohol-based support in lens-shaped form, has been used for several
applications in carbohydrate processing. Among these are the synthesis of oligosaccharides with dextransucrase (de Segura et al. 2003), maltodextrin hydrolysis with
glucoamylase (Rebroš et al. 2006), lactose hydrolysis with lactase (Grosová et al.
S. Farooq et al.