Analyses of lipids release from alginate capsules within the simulated gastrointestinal environment
This work aims to assess the behaviour of alginate capsules with essential lipids and to characterise their transport rates under simulated gastrointestinal conditions. The maximum encapsulation efficiency can be attained in the alginate capsules with oil loadings up to 40% (w/w). The results on the emulsion efficiency of sodium alginate – oil containing capsules at different oil loading capacity show that our preparations are able to hold the encapsulated oil and therefore deliver in a certaine place of a model human digestive system. Changes in mechanical properties reflected changes in the gel microstructure with the capsules becoming stronger in gastric phase (values of Young’s modulus of about 7 × 104 Pa) and weaker in intestinal conditions (Young’s modulus ≈ 1 × 104 Pa). Results on the swelling behaviour showed that all capsules shrink in gastric and swell in intestinal conditions. The amount of oil encapsulated in the capsules remains stable during the gastric stage, whereas the residual amount of oil was released from the alginate capsules at the intestinal phase. Mathematical modelling using Fick’s low of diffusion was applied to the rates of lipids release revealing that changes in mechanical properties under media conditions governs the diffusional mobility of lipids in the encapsulated matrix.
Keywords: alginate, capsules, release, in vitro hydrolysis, mechanical properties, mathematical modelling