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Role of Covalent and Noncovalent Interactions in the Formation of Films from Unheated Whey Protein Solutions Following pH Adjustment
Author(s) -
Quinn G.,
Monahan F.J.,
O'Riordan E.D.,
O'SUllivan M.,
Longares A.
Publication year - 2003
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.2003.tb05760.x
Subject(s) - solubility , dithiothreitol , chemistry , whey protein isolate , ultimate tensile strength , elongation , dispersion (optics) , whey protein , chemical engineering , covalent bond , chromatography , polymer chemistry , materials science , organic chemistry , composite material , enzyme , physics , optics , engineering
Films were formed from heated whey protein isolate (WPI) solutions (heated [H] films) and from unheated WPI solutions following adjustment to pH 11, with subsequent readjustment to pH 7 (unheated, readjusted [UR] films) or without readjustment to pH 7 (unheated, unadjusted films [UU] films). UU and UR films had significantly lower % elongation, tensile strength, and Young's modulus than H films. Film solubility and dispersion in water were in the order: H films < UU films < UR films. Free sulphydryl groups were lower and disulphide‐mediated polymerization was higher in heated than in unheated WPI solutions whereas solubility of H films increased in the presence of dithiothreitol.