The achievement of a glassy state is determinant for the encapsulation of volatile and non volatile compounds that become entrapped in the system during the vitrification process. Process factors, thermal hystory and compositional factors affect retention ability and physical properties of the low moisture/dry encapsulated amorphous materials. While spray drying is a widely applied technology in flavour encapsulation, alternative and innovative technologies exist and/or are under development to improve technological performances, quality and stability of glassy encapsulates. In recent times, milling and comilling are receiving some attention in the pharmaceutical and food sector due to their ability to induce crystal-to-glass transformations at temperature below Tg and to modify the physical properties and functionality of materials. Scarce are the information about the role of small molecules like volatile aroma compounds in affecting their physical properties and mobility of carbohydrate glassy encapsulating matrices. Aim of this study was to deepen the impact of two different glass-forming technologies applied to a mix of limonene, a hydrophobic aroma compound, and trehalose on the physical properties and molecular mobility of the corresponding amorphous encapsulating matrices. To this aim, spray drying as example of a dehydration technique and milling/comilling were applied; phase properties and molecular dynamics were investigated by DSC and a combination of low- and high-resolution solid-state NMR experiments; limonene retention was also evaluated by GC-MS techniques. Investigations were carried out just after preparation and after storage under controlled environmental conditions. Thermal analysis and solid-state NMR spectroscopy highlighted a significant difference between the spray-dried and comilled samples that could be partly ascribed to the different amorphisation procedure and the structural properties of the low moisture products. Presence and content of limonene in the comilled amorphous systems did not determine changes in the Tg of the glassy liquid-solid dispersion, while it modified significantly the kinetics of cold-crystallisation and melting. Phase separation between limonene and trehalose was always observed, but differences in limonene dynamics were found to depend on limonene content and droplets dimensions.

Thermal properties and molecular mobility of amorphous trehalose-limonene matrices obtained by different glass-forming approaches: Desolvatation vs. solid state

255th National Meeting (2018)

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