As the pH is lowered, i.e. , as the hydrogen ion concentration of the solution is increased , ionization of the carboxylate groups is repressed , i.e. , the highly hydrated carboxylate groups are converted int o only slightly hydrated carboxylic acid groups. As a result of losing some of their charge, the polysaccharide molecules no longer repel each other over their entire length ; and as a result of losing some of the water of hydration , they can associate over a portion of their length to form a gel . Apparent pK values (pH at 50% dissociation ) vary with the DE of the pectin (22); a 65% DE pectin has an apparent pK of 3.55, while a 0ί DE pectic acid has an apparent pK of 4.10. However, pectins with increasingly greater degrees of methylation will gel at somewhat higher pH, undoubtedly because they have fewer carboxylate anions at any given pH (See late r paragraph). pH affect s gel texture
more than gel strength .