Effect of selected Hofmeister salts on textural and rheological properties of nonfat cheese

Exopolysaccharide from marine microalgae belonging to the Glossomastix genus: fragile gel behavior and suspension stability

With the aim to find new polysaccharides of rheological interest with innovated properties, rhamnofucans produced as exopolysaccharides (EPS) in a photobioreactor (PBR) and an airlift bioreactor (ABR) by the marine microalgae Glossomastix sp. RCC3707 and RCC3688 were fully studied. Chemical characterizations have been conducted (UHPLC - MS HR). Analyses by size-exclusion chromatography (SEC) coupled online with a multiangle light scattering detector (MALS) and a differential refractive index detector showed the presence of large structures with molar masses higher than 106 g.mol-1. The rheological studies of these EPS solutions, conducted at different concentrations and salinities, have evidenced interesting and rare behavior characteristic of weak and fragile hydrogels i.e. gel behavior with very low elastic moduli (between 10-2 and 10 Pa) and yield stresses (between 10-2 and 2 Pa) according to the EPS source, concentration, and salinity. These results were confirmed by diffusing wave spectroscopy. Finally, as one of potential application, solutions of EPS from Glossomastix sp. have evidenced very good properties as anti-settling stabilizers, using microcrystalline cellulose particles as model, studied by multiple light scattering (MLS) with utilization in cosmetic or food industry. Compared to alginate solution with same viscosity for which sedimentation is observed over few hours, microalgae EPS leads to a stable suspension over few days.

Probing the structure-holding interactions in cheeses by dissociating agents - A review and an experimental evaluation with emmental cheese

Interactions holding protein structure in cheese has been a subject of considerable investigation, with conclusions varying among studies. We present a review on this topic, covering fresh curds, ripened cheeses, and processed cheeses. We discuss the usual chemicals and conditions used to probe different types of interactions. Furthermore, we did our own study with solutions of urea, SDS, EDTA, NaCl, and NaOH, at different concentrations and combinations, for Emmental cheese. To quantify solubilized protein, we developed a modification of a spectrometric-based method that can be conveniently employed to quantify total protein in cheese, with statistically similar results to those obtained by the Kjeldahl method. Our results point out that caseins in the Emmental cheese are held together by a set of hydrophobic interactions, hydrogen bonds, and other electrostatic ones, including ionic bonds. Hydrogen bonds seem to have an important role, comparable to hydrophobic interactions, a conclusion not commonly reported for cheese structures.