Micro-Heterogeneity and Micro-Rheological Properties of High-Viscosity Barley β-Glucan Solutions Studied by Diffusing Wave Spectroscopy (DWS)

Rheological and Micro-Rheological Properties of Chicory Inulin Gels

As a soluble fiber, inulin is present in many plants and has many applications in food and non-food products. In this work, we investigated the rheological properties of inulin dispersions at seven concentrations. The linear viscoelastic properties of inulin were determined using a conventional mechanical rheometer. At 25 wt%, inulin exhibited fluid-like viscoelastic liquid behavior. However, when concentrations were ≥27.5 wt%, inulin exhibited gel-like viscoelastic properties. The viscoelastic properties (moduli and viscosities) increased with increasing inulin concentration. The high-frequency linear rheological properties of inulin were also investigated using the modern light scattering technique, diffusion wave spectroscopy (DWS). The diffusion wave spectroscopy (DWS) measurements showed the amplitude of complex moduli (|G*(ω)|) of inulin gels (≥27.5 wt%) to be proportional to ½ power law of the frequency, which suggests inulin gels behave similarly to flexible polymers. The non-linear steady shear experiments demonstrated that inulin exhibited shear-thinning behavior that was well fitted by a power law constitutive model. The trend of the power law exponent from the experiments indicated that the shear-thinning extent for inulin was greater as the inulin concentration increased. The results of this work indicated that the properties of inulin gel can be manipulated by altering its concentration. Therefore, the desired inulin product can be designed accordingly. These results can be used to direct further food and non-food applications, such as wound healing materials for inulin gels.

Effect of cationic monomer structure on the aggregation behavior of amphoteric acrylic polymer around isoelectric point

Amphoteric polymer can be used as retanning agent in leather manufacture. It is particularly useful in chrome-free tanning systems since it can regulate the charge properties of chrome-free leather and enhance the fixation of anionic post-tanning chemicals in leather. However, the aggregation and precipitation of amphoteric polymer retanning agents around the isoelectric point (pI) hinder their wide application. Herein, we synthesized five amphoteric acrylic polymers (AAPs) by free radical copolymerization with acrylic acid and five different cationic acrylic monomers. The effect of cationic monomer structure on the aggregation behavior of AAPs was investigated. The aggregation of AAPs in aqueous solution showed pH and concentration dependence. Light scattering analysis showed that Poly (AA-co-MAPTAC) and Poly (AA-co-DMAPMA) were in the shape of coiled linear flexible chains with small particle size (Rg 7.6 nm and 14.8 nm, respectively) near the pI. However, Poly (AA-co-DAC), Poly (AA-co-DMC) and Poly (AA-co-DMAEMA) were in the shape of hollow spheres and exhibited serious aggregation. Quantum chemical calculations suggested that the amide groups in the cationic monomers MAPTAC and DMAPMA enhanced the nucleophilicity of AAPs. Thus the corresponding AAPs could carry a large number of cationic charges to slow their aggregation when the pH just climbed over the pI. The results are expected to provide theoretical reference for the synthesis and widespread application of AAPs.

Wine and Non-Dairy Fermented Beverages: A Novel Source of Pro- and Prebiotics

Probiotics and prebiotics are microbiota-management instruments for improving human health once they may be beneficial for maintaining a healthy community of gut microbiota and bowel function. Probiotic’s main target is the gut, via the gastrointestinal tract, although direct application to other body zones such as the vaginal tract, the oral cavity, and skin have been studied. The major source of probiotics is fermented dairy products, however, currently, there is a need for novel and non-dairy probiotics, due to the increasing number of lactose-intolerant persons in the world population, tied with the adverse effect of cholesterol contained in fermented dairy foods as well as the increasing number of strict vegetarians. In this review, we describe gut-derived effects in humans of possible microorganisms isolated from wine, such as Saccharomyces and non-Saccharomyces yeasts and bacteria, and other non-dairy fermented beverages. Those microorganisms can be grown and consumed as recommended probiotics, moreover, wine, and other beverages may also be a source of prebiotics such as polyphenols.