Protein research collaboration project

Summary

​The goal of the project was to categorise the behaviour of a range of food proteins in the solid state, and predict their response to formulation variables likely to be found in food manufacturing processes and products.
The research conducted in the Protein Syndicate showed that:
The glassy state behaviour of proteins is dependent on the primary structure and the proportion of ordered and non-ordered amorphous structure.
The least structurally-ordered proteins such as gluten and MPC exhibit the sharpest and most easily measured glass transition (though still broader than for synthetic polymers), while highly folded and ordered proteins such as native BSA did not show a detectable glass transition.
An ageing endotherm was shown for all proteins in the glassy state and relates to the thermal history of the sample.
Proteins exhibit a broad glass transition (spanning up to 50ºC) in comparison with homologous polymers, and is a consequence of the heterogeneous nature of the molecular structure and the sequence of amino acids.
Reduction in molecular weight and increase in the proportion of amorphous to ordered regions (salting in) in proteins lowers the glass transition temperature for a given moisture.
Differences in high order supra-molecular and network structures has a limited effect on protein glassy state behaviour but has a profound affect on their functional properties.
Moisture sorption and solubility behaviour is driven by changes in supra-molecular and macro structures such as networks of proteins and not by the glass transition.
Protein-specific behaviour for protein-water interactions could only be detected at about 20% moisture i.e. above the glass to rubbery transition.