Gallic acid microparticles produced by spray chilling technique: Production and characterization

- Soybean based lipid blends were used to encapsulate gallic acid in W/O emulsions.
- Emulsifier concentration, stirring time and speed were assessed to prepare emulsions.
- W/O emulsions were atomized in spray chilling to produce solid lipid microparticles.
- Increasing saturated lipid concentration led to higher encapsulation efficiencies.
- Microparticles had spherical shape and smooth surface covered with fat crystals.

In this work, we evaluated the implementation of spray chilling technique to produce solid lipid microparticles (SLMs) containing gallic acid as a model phenolic compound, using blends of soybean oil (SO) with fully hydrogenated soybean oil (FHSO) as wall materials. Gallic acid aqueous solution was dispersed through lipid blends by the preparation of water-in-oil (W/O) emulsions stabilized by the emulsifier PGPR (polyglycerol polyricinoleate). The conditions of emulsion preparation (concentration of emulsifier, speed and time of stirring) were established by evaluating their kinetic stability. The FHSO/SO proportion and the W/O ratio have been varied for the different formulations. Lipid blends and emulsions flow curves showed Newtonian behavior at 79 °C (preparation temperature). Microparticles with higher FHSO concentrations presented increased encapsulation efficiencies (from 54% to 101%) due to lower gallic acid superficial concentrations. Mean diameters ranged from about 24 μm to 36 μm and were slightly affected by differences in formulations. Scanning electron microscopy revealed microparticles with spherical shape and smooth surface covered with fat crystals. Hence, the use of spray chilling technique may be a good option for the production of SLMs loaded with phenolics.