Tannic acid cross-linked gelatin–gum arabic coacervate microspheres for sustained release of allyl isothiocyanate: Characterization and in vitro release study

Tannic acid cross-linked gelatin–gum arabic coacervate microspheres, capable of sustained release of allyl isothiocyanate (AITC) with high encapsulation efficiency, were developed for safe and efficient oral delivery of AITC. The microspheres were spherical in shape and clustered. Statistical screening and optimization studies revealed that a maximum AITC encapsulation efficiency could be obtained when the microspheres were prepared with 4.5% total biopolymer, 6.5% oil, and 5.9% AITC in oil phase. Release studies showed that the sustained release performance of the optimized microspheres was greatly enhanced by using more tannic acid without loss in the encapsulation efficiency. The microspheres optimized with 1.5% tannic acid, having an encapsulation efficiency of 83.75% and a mean cluster size of 116.80 μm, released 46% of encapsulated AITC after 2 h in pepsin-containing simulated gastric fluid (pH 1.2), followed by releasing additional 48% in 6 h after being transferred to pancreatin-containing simulated intestinal fluid (pH 7.5).