M. Boulet et al., VOLUMINOSITY OF SOME FOOD PROTEINS IN AQUEOUS DISPERSIONS AT VARIOUS PH AND IONIC STRENGTHS, Food hydrocolloids, 12(4), 1998, pp. 433-441
Commercial casein and whey protein and laboratory preparation of soybe
an protein of various pH were dispersed in distilled water at the init
ial concentration of 4.0% w/v and then diluted with NaCl solutions of
known ionic strengths (mu). Viscosity was measured and voluminosity (V
-e = ml/g) was calculated using Lee's equation relating volume fractio
n (phi(v)) to relative viscosity: eta/eta(o) = 1 + 2.5 phi(v) + 7.031
phi(v)(2) + 37.371 phi(v)(3). The combined effects of pH and mu on V-e
were determined from regression analysis. V-e was inversely related t
o mu between 0.005 and 0.07 M and increased with pH between 6 and 8 an
d decreased at higher pH. The results are discussed in terms of the re
lationship between the protein electrostatic charges and structure. It
is concluded that in associative proteins V-e is controlled by the nu
mber of electrostatic charges and their strength. (C) 1998 Published b
y Elsevier Science Ltd. All rights reserved.