Formulation and Characterization of Alginate Beads with HPMC Containing Eugenol for pH Sensitive Release

Eugenol is a natural phenolic compound with strong antimicrobial and antioxidant activity. Despite its benefits, its volatility and low stability limit its practical applications. To overcome this issue, it has been encapsulated in alginate beads via ionic gelation with CaCl2 as crosslinker. To enhance the sustained release and the swelling properties, a fixed amount of hydroxypropyl methylcellulose (HPMC) was incorporated into the formulation. Fresh beads with white colour exhibited two distinct shapes, spherical and teardrop, with sizes ranging between 2.53 and 3.30 mm. The effect of alginate and CaCl2 concentrations on the encapsulation efficiency (EE) was investigated, and it was found that the highest EE of 78.8 % was achieved with 2 % w/v alginate and 5 % w/v CaCl2. Beads formulated with 4 % alginate and 7 % w/v CaCl2 showed an EE of 73 % while an increase in the EE from 55.6 % to 72.2 % was observed when the alginate concentration increased to 6 % w/v. Furthermore, the beads demonstrated selective swelling in buffer medium (pH 6.8) and maintained their structure in acidic medium (pH 1.2). Scanning Electron Microscopy (SEM) revealed the presence of nano/microscopic pores on the rippled surface of the beads, which may explain the swelling effect. These findings convey that eugenol encapsulation in alginate beads potentially provides a feasible approach for achieving sustained and targeted release in biotechnical and nutritional products while protecting it from degradation and other factors that could alter its effectiveness.