Investigation of heat-acid induced coagulation behaviour of whole milk systems employing front-face fluorescence spectroscopy

The heat-acid-induced coagulation behaviour of whole milk system (buffalo, cow and mixed milk) was studied by steady-state fluorescence spectroscopy exploiting tryptophan as a marker molecule. The varied molecular environment of tryptophan residues in the raw milk systems exerted different fluorescence properties. During the coagulation process, cow milk exhibited significant quenching and bathochromic shift in the emission spectra which was attributed to the low buffering ability and high hydration capacity of cow milk caseins. The results indicated that tryptophan residues of cow milk experienced more dynamic environment throughout the reaction as compared to buffalo milk.