| An improved calculation procedure on surface composition of spray dried protein-sugar systems |
| Drying Technology ，2015 , 33: 817-821 |
| In this short article, we present a new calculation procedure to estimate the surface concentration of any solute species for spray-dried multi-component particles based on the surface coverage data measured by the X-ray photoelectron spectroscopy (XPS) technique. In contrast to the continuum-theory-based estimation method, this new approach takes into account microscale molecular packing in the XPS detectable surface layer. Hence, it allows a more realistic interpretation of the XPS surface coverage data. Sample calculations on a lactose-casein two-component system demonstrate the effectiveness of the new method and prove indirectly the validity of a distributed parameter model for surface composition prediction. More importantly, the difference between XPS measurements and model predictions can be rationally explained when molecular level interpretation comes into play. |
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