EFECT OF SMOKING ON THE ACCUMULATION OF POLYCYCLIC AROMATIC HIDROCARBONS, IN M. LONGISIMUS DORSI FROM PIGS AND POSSIBILITIES FOR REDUCING THEIR CONTENT

This study deals with the effect of smoking process and the accumulation of toxic polycyclic aromatic hydrocarbons in Musculus Longissimus dorsi from pigs and studies the possibilities to reduce their content. The studies were conducted on two samples boiled-smoked fillet – one salted with brine and added proteincoating, whereas the second one salted with brine and added ascorbic acid.Qualitative identification and quantification of polycyclic aromatic hydrocarbons is done by gas hromotograph Hewlett Packard 5890 with LG 85 B spectrophotometric detector. It was found that the use of proteincoatings, significantly reduces the amount of polycyclic aromatic hydrocarbons in the smoking of Musculus Longissimus dorsi from pigs. The addition of ascorbic acid in conjunction with protein salting coatings technology represents a significant option for reducing the content of the benzo(a)pyrene , which contributes to the safety in the final products. In studies of the samples of proteins and ascorbic acid, the inner layers i.e the muscle tissue was found to contain significantly less amount of benzo(a)pyrene (1,75 ± 0,06 μ/kg) compared with the values found in the surface layers (2,31 ± 0,02 μg/kg)

Analytical modeling of micelle growth. 3. Electrostatic free energy of ionic wormlike micelles -- effects of activity coefficients and spatially confined electric double layers

Hypotheses: To correctly predict the aggregation number and size of wormlike micelles from ionic surfactants, the molecular-thermodynamic theory has to calculate the free energy per molecule in the micelle with accuracy better than 0.01 kT, which is a serious challenge. The problem could be solved if the effects of mutual confinement of micelle counterion atmospheres, as well as the effects of counterion binding, surface curvature and ionic interactions in the electric double layer (EDL), are accurately described. Theory: The electric field is calculated using an appropriate cell model, which takes into account the aforementioned effects. Expressions for the activity coefficients have been used, which vary across the EDL and describe the electrostatic, hard sphere, and specific interactions between the ions. New approach for fast numerical calculation of the electrostatic free energy is developed. Findings: The numerical results demonstrate the variation of quantities characterizing the EDL of cylindrical and spherical micelles with the rise of electrolyte concentration. The effect of activity coefficients leads to higher values of the free energy per surfactant molecule in the micelle as compared with the case of neglected ionic interactions. The results are essential for the correct prediction of the size of wormlike micelles from ionic surfactants. This study can be extended to mixed micelles of ionic and nonionic surfactants for interpretation of the observed synergistic effects.Comment: 36 pages, 6 figures, Supplementary Information: 12 pages, 1 figur

Optical microrheology using rotating laser-trapped particles

We demonstrate an optical system that can apply and accurately measure the torque exerted by the trapping beam on a rotating birefringent probe particle. This allows the viscosity and surface effects within liquid media to be measured quantitatively on a micron-size scale using a trapped rotating spherical probe particle. We use the system to measure the viscosity inside a prototype cellular structure.Comment: 5 pages, 4 figures. v2: bibliographic details, minor text correction

Funkcionalne osobine sojeva bakterija mlečne kiseline i mikrokoka u sredini sličnoj mesnoj masi sirovih kobasica kao modelu

In this study we investigated the potential probiotic properties of Lactobacillus plantarum L 24 - 2, Lactococcus lactis biovar diacetylactis N 237 and strain Micrococcus sp. It has been found that microbial species exhibited the ability to survive under conditions of high concentrations of bile salts (2.0%) and low pH (2.0). This ability varies for different types, but they will remain until the end of experiments zivotosposobne. This, together with the antimicrobial activity projavljenoj them makes them suitable for the new composition uklucivane the starter culture, which can be effectively used as an antimicrobial barrier to the development of pathogenic bacteria in the manufacture of a crude - product of dried meat.U ovom radu su ispitivana potencijalna probiotska svojstva bakterija Lactobacillus Plantarum soj L 24 - 2, Lactococcus lactis biovar diacetilactis soj N 237 i Micrococcus sp. Utvrđeno je da mikrobne vrste pokazuju sposobnost za preživljavanje pod uslovima visoke koncentracije žučnih soli (2,0%) i niskog pH (2.0). Ova sposobnost varira kod različitih ispitivanih bakterija, ali sve one ostaju životno sposobne do kraja eksperimenata. Ovo, zajedno sa dokazanom antimikrobnom aktivnošću čini ih pogodnim za uključivane u sastav novih starter kultura, koje mogu efikasno poslužiti kao antimikrobna barijera za razvoj patogenih bakterija u proizvodnji sirovih - sušenih proizvoda od mesa

Direct measurements of the effects of salt and surfactant on interaction forces between colloidal particles at water-oil interfaces

The forces between colloidal particles at a decane-water interface, in the presence of low concentrations of a monovalent salt (NaCl) and of the surfactant sodium dodecylsulfate (SDS) in the aqueous subphase, have been studied using laser tweezers. In the absence of electrolyte and surfactant, particle interactions exhibit a long-range repulsion, yet the variation of the interaction for different particle pairs is found to be considerable. Averaging over several particle pairs was hence found to be necessary to obtain reliable assessment of the effects of salt and surfactant. It has previously been suggested that the repulsion is consistent with electrostatic interactions between a small number of dissociated charges in the oil phase, leading to a decay with distance to the power -4 and an absence of any effect of electrolyte concentration. However, the present work demonstrates that increasing the electrolyte concentration does yield, on average, a reduction of the magnitude of the interaction force with electrolyte concentration. This implies that charges on the water side also contribute significantly to the electrostatic interactions. An increase in the concentration of SDS leads to a similar decrease of the interaction force. Moreover the repulsion at fixed SDS concentrations decreases over longer times. Finally, measurements of three-body interactions provide insight into the anisotropic nature of the interactions. The unique time-dependent and anisotropic interactions between particles at the oil-water interface allow tailoring of the aggregation kinetics and structure of the suspension structure.Comment: Submitted to Langmui

Free energy of colloidal particles at the surface of sessile drops

The influence of finite system size on the free energy of a spherical particle floating at the surface of a sessile droplet is studied both analytically and numerically. In the special case that the contact angle at the substrate equals $\pi/2$ a capillary analogue of the method of images is applied in order to calculate small deformations of the droplet shape if an external force is applied to the particle. The type of boundary conditions for the droplet shape at the substrate determines the sign of the capillary monopole associated with the image particle. Therefore, the free energy of the particle, which is proportional to the interaction energy of the original particle with its image, can be of either sign, too. The analytic solutions, given by the Green's function of the capillary equation, are constructed such that the condition of the forces acting on the droplet being balanced and of the volume constraint are fulfilled. Besides the known phenomena of attraction of a particle to a free contact line and repulsion from a pinned one, we observe a local free energy minimum for the particle being located at the drop apex or at an intermediate angle, respectively. This peculiarity can be traced back to a non-monotonic behavior of the Green's function, which reflects the interplay between the deformations of the droplet shape and the volume constraint.Comment: 24 pages, 19 figure