Impact of molecular weight and deacetylation degree of chitosan on the bioaccessibility of quercetin encapsulated in alginate/chitosan-coated zein nanoparticles.

This work aimed at studying the effect of molecular weight (MW) and deacetylation degree (DD) of chitosan on the quercetin bioaccessibility encapsulated in alginate/chitosan-coated zein nanoparticles (alg/chiZN). The chitosan coating layer produced nanoparticulate systems with good stability parameters, high encapsulation efficiency (EE) and a higher bioaccessibilty of quercetin after in-vitro digestion. By increasing the DD of chitosan, the ζ-potential of the colloidal system significantly increased (≥27.1 mV), while low and very low MW chitosans generated systems with smaller particle sizes (≤ 277.8 nm) and polydispersity index [PDI (0.189)]. The best results, in terms of EE (≥84.44) and bioaccessibility (≥76.70), were obtained when the systems were prepared with low MW chitosan and high DD. Thus, the alg/chiZN nanocapsules may be a promising delivery system for improving the quercetin bioaccessibility or other compounds with a similar chemical nature, especially when higher DD and lower MWs are used.

Electrosprayed Agar Nanocapsules as Edible Carriers of Bioactive Compounds.

Electrosprayed agar nanocapsules were developed using an acetic acid solution as solvent. The role of solution properties (viscosity, surface tension, and conductivity) in the formation of agar particles was assessed, together with the effect of both agar and acetic acid concentrations on the size and morphology of the resulting particles. Agar solutions with a concentration below 10% w/v were not suitable for electrospraying. Furthermore, the agar-acetic acid ratio was also critical for the formation of agar nanostructures (with an optimum ratio of 1:2). A decrease in particle size was also observed when decreasing agar concentration, with particle diameter values ranging between 50 and 400 nm. Moreover, the suitability of the electrosprayed agar nanocapsules as carriers for a model bioactive compound, chlorophyllin sodium copper salt (CHL), was also evaluated. The release profile of encapsulated CHL, with an estimated encapsulation efficiency of around 40%, was carried out in food simulants with different hydrophilicity (10% v/v and 50% v/v ethanol). While the release of the bioactive was negligible in the hydrophilic food simulant, an initial burst release followed by a slower sustained release was observed when the capsules were immersed in 50% ethanol solution. The results open up a broad range of possibilities that deserve further exploration related to the use of these edible polysaccharide-based nanocapsules.