Development of chitosan coated agar-gelatin particles for probiotic delivery and targeted release in the gastrointestinal tract

This study reports the development of a novel and simple formulation for probiotic delivery using chitosan-coated agar-gelatin gel particles. This methodology involves the production of agar-gelatin particles by thermally treating a mixture of agar and gelatin solutions at high temperatures (121°C) and subsequently coating with chitosan. The particles were able to protect the probiotic strain Lactobacillus plantarum NCIMB 8826 during incubation for 2 hours in simulated gastric fluid (pH 2) as no statistically significant loss (P > 0.05) in cell concentration was observed, and also resist dissolution in simulated intestinal fluid (pH 7.2). Interestingly, this protection is related to the fact that the intense thermal treatment affected the physicochemical properties of agars, and resulted in the formation of a strong and tight polymer network, as indicated by the X-ray diffraction (XRD) analysis. Using an in vitro faecal batch fermentation model simulating the conditions of the distal part of the large intestine (pH 6.7-6.9), it was demonstrated by quantitative real time PCR that the majority of L. plantarum cells were released from the agar-gelatin particles within 30 to 48 hours. Overall, this work led to the development of a novel methodology for the production of probiotic containing particles which is simpler compared to current encapsulation technologies, and has a lot of potential to be used for the controlled release of probiotics and potentially other solid bioactives in the large intestine.