Heat-Induced Gelation of Globular Protein Mixtures
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Heat-induced conformational changes and heat-induced gels of whey and egg white albumen, and their major components were studied under physicochemical conditions that favour protein-protein interactions. We used differential scanning calorimetry (DSC) to compare their conformational heat stability, through the characteristic temperature (Θmax) corresponding to the maximal heat flow and the overall calorimetric heat of reaction (Δr H cal). Times needed to observe sol-gel state transitions at various temperatures were determined by a tilting test and the corresponding time-temperature experimental points were best fitted to two successive Arrhenius plots intersecting at Θ∼Θmax corresponding to the major protein component for whey proteins and to a minor protein component for egg white albumen. Observations of gel-networks by scanning electron microscopy indicated a wide range of stuctural patterns, depending on the composition of protein solutions. The results are discussed in terms of the temperature of maximal rate of heat-induced conformational changes and of sol-gel state transitions of protein molecules.
KeywordsDSC egg white proteins SEM sol-gel transition whey proteins
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