Definition and applications of the network glass transition temperature

A cursory exploration of the recent literature on the vitrification of food materials using a scientific search engine downloads a plethora of documents. Thermal analysis has been an effective tool in mapping out the physical behaviour of pure ingredients, but it has not been the technique of choice in synthetic polymer research for the rationalisation of molecular dynamics in the rubber-to-glass transition. A new concept of ‘the network Tg’ has been developed using small deformation mechanical analysis and a combination of the WLF/free volume theory with the modified Arrhenius equation. The network Tg is distinct from the empirical DSC Tg and the two indicators should be used in tandem to rationalise phase phenomena in biomaterials. Applications of the network Tg are explored in model confections, dehydrated foodstuffs, state diagrams and adsorption isotherms.