Influence of ethanol on the rennet-induced coagulation of milk

The influence of ethanol on the rennet-induced coagulation of milk was studied to investigate potential synergistic effects of these two mechanisms of destabilisation on the casein micelles. Addition of 5% (v/v) ethanol reduced the rennet coagulation time (RCT) of milk, whereas higher levels of ethanol (10-20%, v/v) progressively increased RCT. The temperature at which milk was coagulable by rennet decreased with increasing ethanol content of the milk. The primary stage of rennet coagulation, i.e., the enzymatic hydrolysis of kappa-casein, was progressively slowed with increasing ethanol content (5-20%, v/v), possibly due to ethanol-induced conformational changes in the enzyme molecule. The secondary stage of rennet coagulation, i.e., the aggregation of kappa-casein-depleted micelles, was enhanced in the presence of 5-15% ethanol, the effect being largest at 5% ethanol. Enhanced aggregation of micelles is probably due to an ethanol-induced decrease in inter-micellar steric repulsion. These results indicate an interrelationship between the effects of ethanol and chymosin on the casein micelles in milk, which may have interesting implications for properties of dairy products.     

Assessing the Potential Content of Ethyl Carbamate in White,Red, and Rosé Wines as a Key Factor for Pursuing Urea Degradation by Purified Acid Urease

The ethyl carbamate (EC) content of a wine after a given temperature‐time storage was theoretically predicted from the potential concentration of ethyl carbamate (PEC), as determined via an accelerated EC formation test. Such information was used to decide whether an enzymatic treatment was needed to reduce the wine urea level before bottling/aging. To this end, 6 white, red, and rosé wines, manufactured in Italy as such or enriched with urea, were tested for their PEC content either before or after enzymatic treatment using a purified acid urease preparation derived from Lactobacillus fermentum. The treatment was severely affected by the total phenolic content (TP) of the wine, the estimated pseudo‐first‐order kinetic rate constant for NH₃ formation reducing by a factor of approximately 2000 as the TP increased from 0 to 1.64 g L^‐1. Such a sensitivity to TP was by far greater than that pertaining to a killed cell‐based enzyme preparation used previously. Urea hydrolysis was successful at reducing EC concentration in wines with low levels of TP and other EC precursors.     

Modeling the flexural fatigue behavior of glass-fiber-reinforced thermoplastic matrices

A two-parameter model explicitly accounting for the cyclic as well as the mean stress was proposed and tested on the basis of static and fatigue data obtained in four-point bending on a random continuous glass-fiber-reinforced polypropylene. The model is based on residual strength degradation and captures the effect of stress ratio (i.e. the ratio between the minimal and the maximal stress). The experimental data were in excellent agreement with the theoretical predictions, indicating that a fatigue characterization can be achieved with a minimum of experimental tests. Further, the reasonable agreement between the static strength data and the theoretical predictions highlighted the potential and reliability of the model in view of its statistical implementation     

Nitrogen gas purging for the deoxygenation of polyaromatic hydrocarbon solutions in cyclohexane for routine fluorescence analysis

During routine fluorescence analysis, the presence of dissolved oxygen in solutions can result in the dynamic quenching of a fluorophore's emission through collisional deexcitation of the fluorophore's excited state. In order to avoid this type of fluorescence quenching, dissolved oxygen is often removed from solutions by an inert gas purging procedure. However, the details and quantification of this purging process are often limited in fluorescence studies. In this work, standard 10 mm x 10 mm fluorescence cuvettes are filled with polyaromatic hydrocarbon (PAH) solutions in cyclohexane and purged using nitrogen gas, and the experimental purging parameters (nitrogen flow rate, amount of volatile solvent loss, and rate of oxygen removal) are measured and analyzed. For experimental conditions similar to those used in this study, we are able to provide useful guidelines for the deoxygenation of solutions, specifically the purge times required for solutions of fluorophores with various fluorescence lifetimes. Enhancement factors, or F(0)/F values (the ratio of fluorescence intensity of a completely deoxygenated solution to the fluorescence intensity of an aerated solution), for chrysene, phenanthrene, naphthalene, and pyrene solutions in cyclohexane were found to be 3.61 +/- 0.02, 4.17 +/- 0.02, 7.63 +/- 0.07, and 21.81 +/- 0.35, respectively.     

Spectrograph based on a single diffractive element for real-time measurement of circular dichroism

In this study, a novel and simple diffractive spectrographic method for real-time measurements of circular dichroism (CD) is considered from a theoretical and experimental approach. A demonstrator prototype of the CD spectrograph has been developed and its performance has been compared with a commercial phase-modulation CD spectrometer. The main element of the device is a polarization holographic grating, recorded in a thin photosensitive organic film, by two interfering opposite circularly polarized beams. A peculiarity of this grating is that the amplitude of the +1 (-1) order of diffraction is proportional to the right (left) circular polarization component of the incoming beam. Here we demonstrate that the CD spectrum of a specimen can be easily evaluated from the intensities of the diffracted beams. A white light beam passing through the specimen is diffracted from the grating and the intensities of the +/-1 orders of diffraction are measured. Due to the spectral selectivity of the grating, the CD at each wavelength can be evaluated at the same time using two linear array detectors.     

Synthesis, biological activity, and ADME properties of novel S-DABOs/N-DABOs as HIV reverse transcriptase inhibitors

Previous studies aimed at exploring the SAR of C2-functionalized S-DABOs demonstrated that the substituent at this position plays a key role in the inhibition of both wild-type RT and drug-resistant enzymes, particularly the K103N mutant form. The introduction of a cyclopropyl group led us to the discovery of a potent inhibitor with picomolar activity against wild-type RT and nanomolar activity against many key mutant forms such as K103N. Despite its excellent antiviral profile, this compound suffers from a suboptimal ADME profile typical of many S-DABO analogues, but it could, however, represent a promising candidate as an anti-HIV microbicide. In the present work, a new series of S-DABO/N-DABO derivatives were synthesized to obtain additional SAR information on the C2-position and in particular to improve ADME properties while maintaining a good activity profile against HIV-1 RT. In vitro ADME properties (PAMPA permeation, water solubility, and metabolic stability) were also experimentally evaluated for the most interesting compounds to obtain a reliable indication of their plasma levels after oral administration.     

Sorption of humic acids by a zeolite-feldspar-bearing tuff in batch and fixed-bed column

The sorption of humic acids (HA) on zeolite-feldspar-bearing Phlegraean Yellow Tuff enriched with calcium ions has been investigated at neutral pH both on fixed-bed columns and in batch. A two-step sorption kinetics and a relatively long time to reach the equilibrium were observed in batch. In line with this behaviour, the breakthrough curves and shipping curves from exhaust columns showed distinctive properties that cannot be easily modelled by the common mass balance equations; noteworthy, the breakthrough curves were dependent on the space velocity also for very slow processes and the bed sorption capacity decreased linearly with the space velocity. Moreover, after an initial high-rate burst, HA desorption from exhausted columns proceeded at a very slow rate, particularly so for columns loaded with higher amounts of HA.     

Beta-glucans improve growth, viability and colonization of probiotic microorganisms

Probiotics, prebiotics and synbiotics are frequently-used components for the elaboration of functional food. Currently, most of the commercialized probiotics are limited to a few strains of the genera Bifidobacteria, Lactobacillus and Streptococcus, most of which produce exopolysaccharides (EPS). This suggests that the beneficial properties of these microorganisms may be related to the biological activities of these biopolymers. In this work we report that a 2-substituted-(1,3)-β-d-glucan of non-dairy bacterial origin has a prebiotic effect on three probiotic strains. Moreover, the presence of this β-d-glucan potentiates in vitro adhesion of the probiotic Lactobacillus plantarum WCFS1 to human intestinal epithelial cells.