Factor affecting morphology, thermal and structural properties of pennisetin microparticles prepared by solvent phase separation

A. Bensalem, S. Mosbahi, H. Amoura, A. Charabi, M. Rogalski, P. Magri, B. Nadjemi, H. Mokrane


Pearl millet prolamin, a non gluten protein called pennisetin, was used to formulate microparticles by phase separation, using glacial acetic acid (10%) and aqueous ethanol (70%). Optical microscopy (OM) and scanning electron microscopy (SEM) showed that microparticles produced by aqueous ethanol (ME) were spherical with smooth surface and their average diameter was 13 ± 2 µm, whereas those prepared with glacial acetic acid (MA) were irregularly shaped with tough surface and high diameters ranging from 22.87 to 119.25 µm. ME morphology was highly affected by antisolvent concentration and mixing speed. Thermogravimetric analysis (TGA) indicated that microparticles began losing weight at 60°C probably due to water evaporation, then a second step of degradation occurred at higher temperature 318, 324°C and 308°C for ME, MA and pennisetin powder, respectively. The differential scanning calorimetry (DSC) showed that ME were more heat stable than MA and the original pennisetin powder. Fourier transform infrared (FTIR) spectra showed an increasing formation of β-sheet structure in ME and MA indicating tendency to protein aggregation during microparticle formation. The pennisetin microparticles developed in this study could be used in bioactive compounds encapsulation for vegans and celiacs.

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