Solid lipid microparticles loaded with cinnamon oleoresin: Characterization, stability and antimicrobial activity.

Cinnamon bark oleoresin (CO) is a natural flavoring that has several biological properties and can act as an antimicrobial agent. However, oleoresins are susceptible to degradation by light, oxygen and temperature. Thus, the objective of this work was the production and characterization of microparticles loaded with CO obtained by the spray chilling technique. Hardfat (PH) and palm oil (PO) were used as carriers in different proportions: 100:0; 80:20; 60:40, respectively. The active concentration was 1 and 2%. Solid lipid microparticles (SLM) were stored at 25 and 45°C having their polymorphism, retention capacity of the volatile compounds and antimicrobial capacity assessed over 28 days. CO presented cinnamaldehyde (Cn), O-methoxy cinnamaldehyde (OmCn) and coumarin (Co) as the major volatile components. The minimum inhibitory concentration (MIC) of the CO against molds, yeasts and Gram-negative bacteria was of 0.1% (v/v), for every microorganism. In the SLM characterization there was a significant size variation, with a mean diameter (d 0.5) in the range of 8-72 μm. Most of the formulations showed crystals in the polymorphic form β '. The formulation containing only PH as the carrier agent and 2% CO was able to better retain the volatile compounds. During the storage period, formulations F2 and F3, containing proportions of HP and OP of 80:20 and 60:40, respectively, and 2% CO, showed the best stabilities in relation to the concentration of Cn. The antimicrobial activity of the SLM against Candida pseudointermedia and Penicillium paneum, evaluated by the diameter of inhibition zone, increased over the 28 days of storage.