The swelling and cleavage reactions depend on the local concentration of hydroxide and so are sensitive
to the rate of transport of hydroxide through the gel. Experiments were performed to determine the effect
of the NaOH concentration on the hydroxide penetration thickness and on the velocity of the penetration
front marked by phenolthalein indicator. Simple simulations and a more advanced semi-theoretical analysis
were performed, with proteins being treated as ideal polyelectrolyte polymers. Both yielded good
agreement with the experimental results. The effective diffusivity of NaOH in the protein gels was found
to be similar to that in water. The analytical procedure can be extended in principle to any protein gel.injection of weak acid into meat tissue