Antioxidant and Antimicrobial Activity of Rosemary Extract in Chicken Frankfurters

ABSTRACT:  The antioxidant and antimicrobial effects of commercially available oil-soluble rosemary extracts VivOX 20 and VivOX 4 were investigated against lipid oxidation and microbial growth in vacuum-packed chicken frankfurters. The content of the main active ingredient, carnosic acid, in extracts was 20% and 4% (w/w), respectively. For comparison, the activity of commercially available preservative Robin LI LS was also tested. The control was chicken frankfurters made without test additives. Antioxidant activity tests were performed at 3 storage temperatures (4, 12, 25 °C), using the Rancimat method. Antimicrobial effect was investigated by aerobic plate count. Results showed that both rosemary preparations possess antioxidant and antimicrobial properties that may make them useful in the food industry. In chicken frankfurters with added VivOX 20 and VivOX 4, higher oxidative stability was exhibited at all storage temperatures, as in frankfurters with Robin LI LS. Addition of VivOX 20, VivOX 4, and Robin LI LS also significantly reduced the aerobic plate count, compared to controls, stored at 4 or 12 °C.     

The cholesterol content of eggs produced by the Slovenian autochthonous Styrian hen

The cholesterol content of eggs produced by the Slovenian autochthonous Styrian hen in comparison with eggs of the Isa Brown, reared in two different rearing systems, was determined. Eggs were collected four times during the year. The cholesterol content was determined by the enzymatic-spectrophotometric method. The influence of genotype, in two different rearing systems, on the cholesterol content in eggs was studied. The cholesterol content determined in eggs from cages was 13.1 ± 0.43 mg g⁻¹ yolk of the Styrian hens as compared to 11.4 ± 0.49 mg g⁻¹ yolk of Isa Brown hens. The cholesterol content determined in free range eggs was 13.6 ± 0.22 mg g⁻¹ yolk of the Styrian hen and 11.8 ± 0.30 mg g⁻¹ yolk of Isa Brown.     

Solubility and diffusivity of CO2 in poly(l-lactide)-hydroxyapatite and poly(d,l-lactide-co-glycolide)-hydroxyapatite composite biomaterials

Solubility and diffusivity of supercritical CO₂ in poly(l-lactide)-hydroxyapatite (PLLA-HA) and poly(d,l-lactide-co-glycolide)-hydroxyapatite (PLGA-HA) composite materials were measured using a magnetic suspension balance at a temperature of 313 K and a pressures range of 10-30 MPa. The effect of the HA concentration on the solubility and diffusivity was investigated by varying filler content in the range of 0-50 wt%. For the PLLA-HA composites the solubility decreases with the increase of filler concentration. Diffusivity of the gas in the substrate is also lower as the HA content increases. In the case of PLGA-HA composites, small filler content favors the solubility and diffusivity of CO₂ due to incomplete wetting of the solid particles by the polymer. As the amount of HA increases solubility decreases. The results suggest that dense CO₂ could be used as a ‘green’ processing agent for composite biomaterials when organic solvents or high temperatures should be avoided.     

High Pressure Micronization of Tristearate

The effect of the pre-expansion temperature, pre-expansion pressure and storage time was studied in order to investigate the crystal form, degree of crystallinity, particle size, particle size distribution and morphology of the tristearate. The experiments were performed at pressures between 115 and 215 bar and at temperatures of 54, 60 and 70 °C with the substance being already melted. Samples were characterized immediately after the experiments and later after 3 months of storage at 5 and 20 °C. Results showed an increase in the amorphous phase. During the storage, the micronized samples re-crystallized. With time, the agglomeration was more emphasized for particles produced at higher temperatures and pressures and stored at a higher temperature. The results of X-ray analysis did not show a change in crystal form of tristearate (β′ form) before and after micronization, however, for samples stored at 20 °C slow transformation from the β′ (less stable) form to the β (more stable) form occurred. In addition, the morphology of micronized samples showed an irregular and porous shape. The re-crystallization was more evident with time for samples stored at 20 °C where needle-like crystals appeared on the surface.     

A BE-based shape optimization method enhanced by topological derivative for sound scattering problems

This paper presents a BE-based shape optimization method for acoustic problems in the context of shape design of sound insulating walls. In order to avoid the convergence to a local minimal solution around an initial shape, the topological derivative is introduced. Based on the global distribution of the topological derivative, new shape or topology are attained by nucleating small scattering bodies. Evaluation of the topological derivative is achieved within the framework of the boundary element analysis. To cope with the topological change due to the nucleation and cutting of thin branches, shape is updated by the aid of the level set approach during the optimization process. Through numerical examples, it is proved that the developed method can find a shape with good performance irrespective of its initial shape.     

An impedance study of two types of stainless steel in Ringer physiological solution containing complexing agents

The effect of complexing agents EDTA and citric acid on the electrochemical behaviour of AISI 304 and orthopaedic stainless steels in Ringer physiological solution was investigated by potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS). The content of Mo has a pronounced effect on the corrosion resistance, as evident by the broader passive range of the orthopaedic stainless steel containing Mo. The addition of complexing agents induces significant changes in polarization and impedance characteristics, i.e., the shift of corrosion and breakdown potentials in a more negative direction, an increase in current density, and a significant decrease in charge transfer resistance. The results were interpreted by the formation of soluble complexes of metal ions with chelating agents, especially EDTA, which suppressed the formation of the outer Fe(III) layer of the passive film. The impact of complexing agent on the electrochemical parameters was found to be related to its concentration in electrolyte and the stability constant of the complex formed with the related metal ion.