Spray dried flaxseed oil powdered microcapsules obtained using milk whey proteins-alginate double layer emulsions.

Spray-dried flaxseed oil microcapsules were produced by designing O/W double-layer emulsions using a whey protein concentrate (WPC) and sodium alginate (SA). The influence of homogenization pressure (5-15 MPa), pH (4-7) and maltodextrin concentration (0.8-7 wt%) on stability of primary and secondary emulsions was investigated, through droplet size and zeta potential measurements. Powders obtained after spray drying were characterized through scanning electron microscopy, encapsulation efficiency and water activity determinations. Flaxseed oil oxidative stability was assessed by measuring peroxide values (PV) and thiobarbituric reactive substances (TBARS) at different microencapsulation processing steps and during powders storage. Droplet sizes of primary emulsions were reduced when increasing homogenization pressures (up to 10 MPa). Zeta potential measurements evidenced double WPC-SA layer formation around oil droplets at pH 5. Encapsulation efficiencies up to 84% were obtained in powdered microcapsules with the highest MD content. Microencapsulation process produced a gradual increment on PV, whereas TBARs slightly increased. Nevertheless, these values were maintained relatively constant after powders storage at -18 and 4 °C for 6 months, and at 20 °C up to 6 weeks and PV did not exceed the maximum allowed for cold pressed oils.

Preparation of TPP-crosslinked chitosan microparticles by spray drying for the controlled delivery of progesterone intended for estrus synchronization in cattle.

PURPOSE: Planned reproduction in cattle involves regulation of estrous cycle and the use of artificial insemination. Cycle control includes the administration of exogenous progesterone during 5-8 days in a controlled manner allowing females to synchronize their ovulation. Several progesterone delivery systems are commercially available but they have several drawbacks. The aim of the present contribution was to evaluate chitosan microparticles entrapping progesterone as an alternative system. METHODS: Microparticles were prepared by spray drying. The effect of formulation parameters and experimental conditions on particle features and delivery was studied. A mathematical model to predict progesterone plasma concentration in animals was developed and validated with experimental data. RESULTS: Microparticle size was not affected by formulation parameters but sphericity enhances as Tween 80 content increases and it impairs as TPP content rises. Z potential decreases as phosphate content rises. Particles remain stable in acidic solution but the addition of surfactant is required to stabilize dispersions in neutral medium. Encapsulation efficiencies was 69-75%. In vitro delivery studies showed burst and diffusion-controlled phases, being progesterone released faster at low pH. In addition, delivery extend in cows was affected mainly by particle size and hormone initial content, while the amount injected altered plasma concentration. Theoretical predictions with excellent accuracy were obtained. CONCLUSION: The mathematical model developed can help to find proper particle features to reach specific delivery rates in the animals. This not only save time, money and effort but also minimized experimentation with animals which is desired from an ethical point of view.