Temperature stable liquid core hydrocolloid capsules

Liquid core spherical alginate-chitosan capsules, encompassing different hydrocolloid concentrations within their membrane, were produced in a single step. This simplified process is advantageous over other multi-stage methods of fluid core capsule production. The contents of the capsule was composed either of distilled water or sucrose solutions of 2, 5 and 30% (w/w), although other viscous liquids can be used. The beads with 0, 2 and 5% sucrose were produced by diffusion of sucrose out of those liquid core capsules containing 30% sucrose. The spherical shape of the capsule was maintained after diffusion. Mechanical properties of various capsules were studied after incubation at 25, 37, 45, 55 and 85°C for 5, 30 and 60 min respectively, while those of the liquid core water capsules were studied for a further 2 weeks at 25°C. Capsules with a higher hydrocolloid concentration within their membrane displayed more stress at failure (strength) and less brittleness than those with lesser solid membrane content. Following diffusion, capsules with 2 and 5% sucrose were weak compared to those with 30% sucrose; however, no membrane breakage was observed after incubation. The weakest capsules were those with water content incubated for longer times at higher temperatures. The manuscript presents the temperature-stability relationship of liquid core capsules. Projections of three-dimensional curves of mechanical property versus time, temperature or percentage sugar, offer a convenient way to examine the desired mechanical properties and their dependence on liquid core composition and incubation conditions.