The impact of food-grade carrageenans and consumer age on the in vitro proteolysis of whey proteins

The food additive carrageenan (E407) (CGN) is a family of sulphated galactans widely used in numerous processed foods, including dairy. There are various indications that CGN may hinder digestive proteolysis. This study sought to link CGN macromolecular characteristics to its implications on digestive proteolysis of whey protein isolate (WPI) in toddlers, adults and seniors. Size exclusion chromatography and dynamic laser scattering reveal commercial CGN samples differ in molecular weight distributions, zeta-potentials and flow behavior of WPI-CGN mixtures. Moreover, κ-CGN, ι-CGN and λ-CGN were found to contain low MW (<200 kDa) fractions at levels of 6.36 ± 2.11% (w/w), 3.64 ± 1.06% (w/w) and 2.08 ± 1.41% (w/w), respectively. In vitro human digestion of WPI-CGN mixtures and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of digesta indicate that CGN alters the breakdown of alpha-lactalbumin, beta-lactoglobulin and lactoferrin differentially in toddlers, adults and seniors digestion conditions. Interestingly, proteomic analyses indicate there is a possible correlation between CGN degree of sulphation and the release of bioactive peptide homologues in the gut lumen. Moreover, these analyses indicate CGN compromises the bioaccessibility of essential amino acids. Altogether, this study shows CGN may attenuate whey digestive proteolysis. This effect should be taken in account by food manufacturers and regulatory agencies in view of the rising levels of exposure to CGN in the human diet.