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Abstract

This paper investigates the crosslinking of sodium alginate with calcium ions through ionotropic gelation to entrap papain using ‘‘environmentally benign’’ solvents. A 3x3 full factorial design was employed to investigate the effect of three process variables namely sodium alginate concentration, calcium chloride concentration and hardening time on % entrapment, time required for 50% (T50) and 90% (T90) of enzyme release, particle size and angle of repose. The beads were prepared by dropping the sodium alginate solution containing enzyme from dropping device to magnetically stirred calcium chloride solution. Furthermore, the desirability function was employed in order to optimize the process under study. It was found that the optimum values of the responses could be obtained at the low levels of all three process variables. Topographical characterization was carried out by taking SEM and entrapment was confirmed using DSC. It was concluded that the proper selection of rate-controlling alginate concentration and their interactive potential for crosslinking is important, and will determine the overall size and shape of beads, the duration and pattern of dissolution profiles, pH sensitivity and enzyme loading capacity.