Chitosan-SDS coacervates for encapsulating amyloglucosidase: a study on structured capsule formation and enzymatic performance

Chitosan, a versatile polymer derived from the deacetylation of chitin, finds extensive applications in food. With its cationic, inert, non-toxic, and biodegradable properties, coupled with gel-forming ability in diverse configurations, chitosan is an attractive biopolymer. This study investigated the formation of chitosan-SDS coacervates for encapsulating amyloglucosidase, a crucial amylolytic enzyme used widely in food and beverage production. Different concentrations of chitosan were dissolved in 0.4% (v/v) acetic acid to give solutions of slightly acidic pH between 5.04 and 5.87 and extruded dropwise (50 drops per minute, 19 mg per drop) into a sodium dodecyl sulfate (50 mM) solution under gentle magnetic stirring. The ionic interaction between chitosan and the anionic surfactant resulted in self-supporting structured capsule production, capsules (diameter 3.04 to 3.5 mm) characterised by a liquid core (diameter 2.30 to 2.59 mm) and a gelled chitosan-SDS membrane (0.74 to 0.91 mm in size), higher chitosan concentrations resulting in larger and more stable capsules. The encapsulation of amyloglucosidase through simple mixing in the chitosan gelling solution allowed for an efficient enzyme separation from the liquid reaction medium with an immobilisation yield of 71% and an enzyme efficiency of 83% compared to the free enzyme form. This mild and food-grade encapsulation process is a novel and promising technique to encapsulate a range of enzymes with enhanced stability and broader applicability due to the better control of product release. The chitosan-SDS coacervates open new possibilities for enzyme incorporation in the food and beverage industry, enhancing product quality and process efficiency.