On the formation of “coral-like” spherical α-glycine crystalline particles

• We demonstrated the fabrication of spherical “coral-like” α-glycine particles.
• Spherical α-glycine particles of 70–100 μm were fabricated via spray drying.
• The drying temperatures had significant effects on internal structure of particle.
• The “coral-like” particle morphology was induced by post-drying humidity treatment.
• The possible mechanisms for the formation of coral-like particles were proposed.

Spray drying can be used to form crystalline amino acid particles of specific size and morphology by adjusting the process conditions. Combined with post-drying humidity treatment, porous and spherical α-glycine particles with “coral-like” morphology were produced by spray drying. Glycine solutions of 8 wt.% and 18 wt.% were spray dried at inlet temperatures between 105 °C and 185 °C using a microfluidic jet spray dryer. The inlet drying temperatures had no significant effect on the polymorphic forms of glycine, but significantly affected their morphology in terms of surface roughness and internal structure. Spray drying provides an easy fabrication approach of spherical α-glycine particles of the particle size in the range of 70–100 μm with less separation, which is a significant advantage over the multiple-step cooling or evaporation processes.

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