Adhesion and aggregation properties of probiotic and pathogen strains

Autoaggregation has been correlated with adhesion, which is known to be a prerequisite for colonization and infection of the gastrointestinal tract by many pathogens. The coaggregation properties of probiotic strains with pathogens as well as their ability to displace pathogens are of importance for therapeutic manipulation of the aberrant intestinal microbiota. Consequently, the ability to aggregate and coaggregate are desirable properties for probiotics in health-promoting foods. Aggregation assays and bacterial adhesion to hydrocarbons (BATH test) demonstrated significant differences in cell surface properties among the tested commercial probiotic strains. Hydrophobicity increased when the cells were heat-inactivated. All probiotic strains tested showed aggregation abilities with the pathogen strains tested, but the results were strain-specific and dependent on time and incubation conditions. Our results indicate that the ability to autoaggregate, together with cell-surface hydrophobicity and coaggregation abilities with pathogen strains can be used for preliminary screening in order to identify potentially probiotic bacteria suitable for human or animal use.     

Effect of strongly competing background compounds on the kinetics of trace organic contaminant desorption from activated carbon

Strongly competing (SC) compounds, naturally found in any drinking water source, are known to decrease the adsorption capacity of activated carbon for trace contaminants. While the effect of these substances on the capacity and adsorption kinetics of trace contaminants is fairly well studied, relatively little is known about their impact on desorption kinetics. The purpose of this study was to investigate the relationship between SC matter and trace compound desorption kinetics. A surrogate SC compound, 1,4-dichlorobenzene (p-DCB), was used to displace the preadsorbed target trace contaminant, atrazine, from powdered activated carbon (PAC). The initial concentrations of p-DCB and atrazine were varied to achieve different degrees of competition to atrazine. Atrazine's desorption diffusion coefficient was found to increase with increasing adsorbed concentration of the SC matter, expressed as an equivalent background compound (EBC).The EBC was modeled with atrazine-like adsorption properties, thus representing the portion of p-DCB that competed to occupy atrazine adsorption sites. The increase in atrazine diffusion rate can be explained by a shift from surface diffusion to diffusion through the carbon's pores as the availability of surface sites decreased due to the EBC's competition. The observed desorption kinetic relationship was consistent with the effect of SC competition on adsorption kinetics; further, the effect was consistent for three different types of SC matter. These findings highlight that the impact of SC matter on activated carbon applications could be either detrimental (displacing adsorbed trace contaminants and enhancing their rate of release) or beneficial (offsetting pore constriction effects by enhancing their rate of uptake).     

Comparative study of the volatile composition in wines obtained from traditional vinification and from the Ganimede method

BACKGROUND: This study compares the volatile composition between wines obtained from vinification carried out by the traditional method or using a new method of vinification (so‐called Ganimede). For this, Shiraz, Merlot and Cabernet Sauvignon musts were fermented by both vinification methods. RESULTS: The volatile compounds that were above their threshold of perception in the wines were practically the same, irrespective of the vinification method used. Most of the compounds studied did not present significant differences in their concentrations between the wines obtained from the traditional and the new vinification methods. When there were significant differences, the concentration of alcohols and acids was higher in the wines vinificated by the traditional method rather than in the wines vinificated by the Ganimede method, whereas for esters, the concentration in the wines depended on the grape variety. CONCLUSION: The Ganimede method favoured polyphenol extraction without greatly affecting the studied volatile composition of the wines. Copyright © 2008 Society of Chemical Industry     

Effects of Spray‐Drying Parameters on In Vitro Functional Properties of Camu‐Camu (Myrciaria dubia Mc. Vaugh): A Typical Amazonian Fruit

Camu‐camu (Myrciaria dubia) fruit is a rich source of bioactive compounds but its shelf life is rather short. Therefore, this study was aimed to evaluate the effect of inlet air temperature (T) and concentration (C) of maltodextrin and arabic gum on the spray‐drying process of commercial camu‐camu pulps (São Paulo and Manaus). Moisture, solubility, total phenolics (TP), ascorbic acid (AA), and proanthocyanidins (PAC) contents, and in vitro antioxidant capacity of the powders (FRAP, DPPH, Folin–Ciocalteu's reducing capacity were measured). Arabic gum resulted in better yields (22% to 30%), powder solubility (84% to 90%), and lower losses of analyzed compounds than the powders manufactured with maltodextrin. Overall, inlet air temperature had a lower impact on the responses studied than the concentration of carrier agents. Polynomial equations were generated for AA (R² = 0.993), TP (R² = 0.735), PAC (R² = 0.946), and for the antioxidant capacity assays (0.867 ≤ R² ≤ 0.963). In addition, principal component analysis showed that the lowest concentration of carrier agents (6%) in spray drying resulted in the lowest losses of bioactive compounds and, consequently, the highest antioxidant capacity.     

Green Banana (<Emphasis Type="Italic">Musa cavendishii</Emphasis>) Osmotic Dehydration by Non-Caloric Solutions: Modeling,Physical-Chemical Properties,Color, and Texture

Osmotic dehydration effects on the kinetics and on some quality attributes of green banana slices (Musa cavendishii) at 25 °C with non-caloric solutes (glycerol, sorbitol, and a mixture of both) at concentrations varying from 40 to 60 g/100 g for up to 6 h were studied. The three-component diagram showed that the first pseudo-equilibrium was achieved, and the water pseudo-diffusion coefficient presented higher values with glycerol solutions. A modified Peleg’s model was applied to obtain the maximum water loss. Changes in green banana physical-chemical properties were observed: moisture content from 1.25 to 0.19 kg/kg dry basis, soluble solute content from 5.4 to 16.9 °Brix; total color-difference from 2.7 to 15.8; and the maximum biaxial extensional viscosity from 0.63 to 1.53 MPa s. Moreover, the obtained low chroma difference values suggest that the osmotically drying process may be a suitable technique to preserve the final color of green banana slices.     

Effect of heating temperature and sodium chloride concentration on ultrastructure and texture of gels made from giant squid (Dosidicus gigas) with addition of starch,l-carrageenan and egg white

This paper seeks to compare the ultrastructure of gels made from frozen muscle of giant squid (Dosidicus gigas) at various temperatures with a number of different rheological parameters, with reference to a variety of added ingredients (non-muscle proteins and hydrocolloids) and to NaCl concentration. Interesting data on gel rheological properties were found where formulae containedl-carrageenan, starch and egg white, with a low salt concentration (1.5%). This seems to be because carrageenan forms an independent network which supports the principal structure formed by the fish protein; starch is incorporated into the network and retains water; and egg white forms a supplementary network which helps to improve rheological properties.     

Highly acetylated pectin from cacao pod husks (Theobroma cacao L.) forms gel

A pectin (OP) obtained from cacao pod husk with a high acetyl content, which is a structural feature that could disturb the pectins' gel formation, was able to form gels at low pH and a high sucrose content. Pectin gels (1.32% GalA equivalent, w/w) were prepared at pH 2.5–3.3 in the presence of 60% sucrose (w/w). Rheological analyses were performed to determine the optimal pH for further studies. Next, the OP samples were prepared at pH 2.7 in concentrations ranging from 0.33 to 1.98% GalA (w/w) with 60% sucrose (w/w) and subjected to rheological analysis. Dynamic oscillatory experiments at 25 °C indicated the presence of gels for all of the analysed concentrations. Measurements of the elastic (G′) and viscous (G″) moduli at 25 °C also indicated that increasing the pectin concentration resulted in stronger gels. Rotational experiments revealed a shear-thinning behaviour in which the apparent viscosities of the samples increased as the concentration increased. Although the OP had a high degree of acetylation, this pectin was able to form gels, which suggests its potential for use as a gelling and thickening additive.