Compositional and structural properties of whey proteins of sweet, acid and salty whey concentrates and their respective spray dried powders

The influence of physiochemical characteristics of whey concentrates obtained by ultrafiltration of acid and salty whey streams on the surface composition, particle organisation, secondary structures and protein interactions of the respective spray dried whey powders was investigated. Their properties were compared with those of native and sweet whey. Acid whey concentrate demonstrated characteristically low surface charge, high surface hydrophobicity, high average particle size and high thiol activity compared with sweet and native whey concentrates. Salty whey concentrate was characterised by low surface hydrophobicity, high thiol activity and low average particle size. Surface characterisation of whey powders revealed protein-rich surfaces for all whey powders while those in salty whey were highly hydrophobic. Protein characteristics of native and sweet whey powders largely followed those of concentrates. In contrast, protein characteristics of the acid and salty whey powders largely changed from those of the concentrates.