Applying In Vitro Digestion Models to Study Carrageenan Interference with Digestive Proteolysis in Infants, Adults and the Elderly

Safety of food additives such as Carrageenan (E407) (CGN) is at the heart of considerable debate due to different indications suggesting adverse effects to human health. Presently, a 2015 JECFA report has determined that use of up to 1000mg/L CGN is not of concern, based on various data including a recent 28 day acute toxicity study in piglets. Yet, recent evidence also suggests that CGN may have anti-nutritional effects on digestive proteolysis with possible long-term effects. This study sought to link CGN macromolecular characteristics to its implications to the gastric degradation of alimentary proteins in infants, adults and the elderly.

First, commercial κ-,ι- and λ-CGN forms were characterized by SEC-MALS and zeta-potential measurements to reveal differences in MW, MW distribution and electrokinetic mobility. Second, CGN samples that were found to interfere with gastric proteolysis of milk, soy and egg protein isolates in adults were confirmed to inhibit pepsin activity. Last, the anti-nutritional effect of CGN was studied in a semi-dynamic infant and elderly IVD-models fed with whey protein isolate or whey proteins mixed with CGN. Subsequently, digesta samples were analysed by SDS-PAGE. Under adult and elderly gastro-intestinal conditions, CGN addition retarded proteolysis of α-lactalbumin and lactoferrin, while β-lactoglobulin breakdown was accelerated in the elderly model. Surprisingly, CGN induced rapid proteolysis of α-lactalbumin but delayed lactoferrin proteolysis in the infant model.

In conclusion, results show that CGN has a complex way of interfering with proteolysis that does not solely depend on CGN-protein biopolymer interactions but also on consumer age. Thus, this study provides new insight into the safety evaluation of CGN and raises the need to address possible risks of CGN to specific consumers.