Carrageenan (CGN), a family of marine polysaccharides isolated from seaweeds, has been at the heart of considerable debate in recent years. To date, CGN is generally recognized as safe based on a history of safe use, various acute toxicology studies and some recent chronic toxicology tests. This review offers readers an overview of evidence on CGN characteristics and digestive fate that highlight various gaps in our understanding. Specifically, three unresolved gaps are identified. Firstly, little information can be found on the current levels of public exposure to CGN. Secondly, the link between CGN physicochemical properties, its impact on digestive proteolysis, the colon microbiome and inflammation are yet to be fully resolved. Thirdly, scant scientific evidence exists on the differential digestive fate of CGN in the gut of liable and predisposed populations, such as elderly people or IBD patients. Altogether, revisiting the scientific evidence indicates that more research is needed to elucidate the possibility that continued exposure to increasing levels of CGN in the human diet may compromise human health and well-being.

The effect of two strong salting‐out salts (Na2SO4 and K2SO4) on the temperature‐induced phase‐separation process in aqueous solutions of poly(N‐isopropylacrylamide) (PNIPA) was examined by attenuated total reflectance/Fourier transform infrared spectroscopy, differential scanning calorimetry, and viscosity measurements. On the basis of these measurements, a detailed scenario of the phase‐separation process was deduced. The phase‐separation scenario of solutions containing PNIPA and water was altered in the presence of sulfate ions. Here, the sulfate ions induced partial intrachain collapse, manifested by a relatively compact structure well below the lower critical solution temperature. This led to a more gradual, smooth phase transition, with temperature‐resolved intrachain collapse and interchain aggregation and a lesser extent of hysteresis. Although at the macrolevel one may not be able to differentiate among various scenarios altering the solvent into a poor solvent, the aforementioned microlevel measurements provided a way to expose the difference between raising the temperature and adding cosolutes. Follow‐up studies on the effect of salting‐in salts will be presented. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 33–46, 2004

This work raises the possibility that CGN may reduce protein and peptide bioaccessibility, disrupt normal epithelial function, promote intestinal inflammation, and consequently compromise consumer health.

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The swelling of polyacrylamide (PAAm) gels increased with rising glucose concentrations, and so did the osmotic pressure of the soluble polymer and its intrinsic viscosity. A Flory-Huggins-based model for the osmotic pressure of a nonionic hydrophilic polymer in a ternary solution consisting of a main solvent, a polymer, and a nondissociating low-molecular-weight cosolute was developed and examined. The model-calculated values were in reasonably good agreement with experimental results for the water-PAAm-glucose system studied when PAAm-water and glucose-water interaction coefficients from the binary systems were used, and only the PAAm-glucose interaction coefficient was adjusted. Its negative value suggested a favorable interaction of glucose and PAAm, supporting the notion of glucose being a good cosolvent for PAAm. Isothermal titration microcalorimetry results showed no evidence for the binding of glucose to PAAm, but an exothermic interaction was indicated between glucose and PAAm. Microcalorimetrically determined enthalpic contributions to the Flory-Huggins interaction coefficients showed enthalpically favorable binary interactions, particularly the enthalpic component of the PAAm-glucose interaction coefficient ( H23 ), which was slightly negative. The enthalpically favorable interaction between glucose and PAAm may explain the increased osmotic pressure of PAAm in glucose solutions.