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Nonthermal gelation of whey proteins induced by organic acids
Author(s) -
Queirós Ana S.,
LopesdaSilva José A.
Publication year - 2017
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.45134
Subject(s) - differential scanning calorimetry , chemistry , rheology , denaturation (fissile materials) , viscoelasticity , acetic acid , enthalpy , whey protein , chemical engineering , alkyl , polymer chemistry , chromatography , organic chemistry , nuclear chemistry , materials science , thermodynamics , engineering , physics , composite material
Gelation of native whey proteins induced by organic acids at ambient temperature was investigated by fundamental small‐deformation oscillatory rheology. Gelling capability, gelation time, and final viscoelastic properties of the gel were dependent on type of acid, protein and acid concentrations, and pH value. Increasing organic acid concentration or increasing the pH (below pI) resulted in lower gelation times and higher gel modulus values. Differential scanning calorimetry demonstrated that the presence of acetic acid significantly reduced denaturation temperature and enthalpy implying a destabilization effect of the protein structure against thermal unfolding, contrarily to what was observed in the presence of HCl at similar pH values. The gelling ability and the denaturing effectiveness of the acids increase with increasing chain length of the alkyl chain, thus suggesting an important contribution of hydrophobic effects promoting denaturation and fostering the establishment of new interactions between the proteins leading to a nonthermal gelation process. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45134.