In this study, we have improved the enteric properties of shellac and developed probiotic formulations
comprising this natural polymer. The effects of plasticizers such as glycerol and glyceryl triacetate, as
well as water-soluble polymers such as sodium alginate, hydroxypropyl methylcellulose and polyvinylpyrrolidone
on thermodynamic characteristics and coating properties of shellac were evaluated. The data
indicate that glycerol showed the best plasticization effect. Hydroxypropyl methylcellulose and polyvinylpyrrolidone
had superior miscibility with shellac compared to sodium alginate. Then, three fluidbed
dried bacterial species i.e., Enterococcus faecium, Bifidobacterium bifidum and Lactobacillus reuteri,
were coated with formulations comprising different concentrations of shellac and additives. Coatings
with shellac containing 5% glycerol or 5% sodium alginate or up to 20% [w/w] polyvinylpyrrolidone protected
the microorganisms against acidic pH and provided the best release profile in simulated intestinal
fluid. Moreover, these formulations maintained promising cell survival rates after four months of storage
at 5 C. E. faecium and B. bifidum showed more resistance to manufacturing process than L. reuteri.