The effect of washing water parameters (pH, hardness and sodium pyrophosphate content) on the water-holding capacity and gelation characteristics of sardine (Sardina pilchardus) mince

In order to determine the effect of washing water parameters [pH, hardness and tetrasodium pyrophosphate (TSPP) content] on the water-holding capacity (WHC) and gelation properties of sardine (Sardina pilchardus) mince, two experiments designed by response surface methodology were carried out. The WHC of the mince was maximum when washed in the pH range of 6.5–7.0, with TSPP>1.7?g???l^-1, and CaCO₃ between 30 and 60?mg???l^-1. With the exception of breaking deformation and the folding test, where the highest values were obtained at 60?mg???l^-1 CaCO₃, the variation of water hardness did not induce any significant changes in the other rheological parameters. The use of relatively high concentrations of TSPP in the leaching water contributed to the achievement of high values of breaking deformation, though beyond 2.5?g???l^-1 a detrimental effect on breaking force was observed, and consequently also on gel strength.     

Incongruence between the cps type 2 genotype and host-related phenotypes of an Enterococcus faecalis food isolate

Enterococcus faecalis is a nosocomial opportunistic pathogen, but is also found in fermented food products where it plays a fundamental role in the fermentation process. Previously, we have described the non-starter E. faecalis cheese isolate QA29b as harboring virulence genes and proven to be virulent in Galleria mellonella virulence model. In this study, we further characterized this food strain concerning traits relevant for the host-pathogen relationship. QA29b was found to belong to sequence type (ST) 72, a common ST among food isolates, and thus we consider it as a good representative of food E. faecalis strains. It demonstrated high ability to form biofilms, to adhere to epithelial cells and was readily eliminated by J774.A1 macrophage cells. Despite carrying the cps locus associated with the capsular polysaccharide CPS 2 type, cps genes were not expressed, likely due to an IS6770 inserted in the cpsC-cpsK promoter region. This work constitutes the first study of traits important for interaction, colonization and infection in the host performed on a good representative of E. faecalis food isolates. Reported results stress the need for a reliable serotyping assay of E. faecalis, as cps genotyping may not be reliable. Overall, QA29b characterization shows that despite its virulence potential in an insect model, this food strain is readily eliminated by mammalian macrophages. Thus, fine tuned approaches combining cellular and mammalian models are needed to address and elucidate the multifactorial aspect of virulence potential associated with food isolates.     

Enzymatic hydrolysis of fish gelatin under high pressure treatment

The effect of high pressure treatment on the hydrolysis of fish skin gelatin and the antioxidant properties of the hydrolysates was evaluated. Hydrolysis was performed by Alcalase, collagenase, trypsin and pepsin both at atmospheric pressure and under high pressure (100 MPa/15 and 30 min, 200 MPa/15 and 30 min, 300 MPa/15 min). The degree of hydrolysis (DH) was determined according to the base consumption via pH‐stat as well as the percentage of soluble nitrogen in trichloroacetic acid (TCA). About 16% of nitrogen in the gelatin was still soluble in 10% TCA, indicative of a significant amount of low molecular weight components. The high pressure treatment increased the DH with all the enzymes used between 5% and 10%. However, in comparison with the hydrolysates obtained at atmospheric pressure after 3 h of digestion under controlled conditions (using a pH‐stat), the radical scavenging capacity of the pressured hydrolysates was only significantly enhanced when Alcalase or collagenase were used. High pressure may be a useful tool for the quick obtaining of gelatin hydrolysates with antioxidant capacity.     

Muscle protein solubility of some cephalopods (pota and octopus) during frozen storage

This study relates to myofibrillar and sarcoplasmic protein solubility in 5% NaCl and collagen solubility in 0.05 M acetic acid, from muscle and mantle of pota (Todaropsis eblanae) and octopus (Eledone cirrhosa) kept in frozen storage for 12 months. In both species, protein solubility in 5% NaCl remained high, over 60%, throughout the storage period. Solubility was lower in the octopus than in the pota lots. The species also behaved differently in terms of the increase in solubility, which occurred earlier in octopus (after 2 months) than in pota (after 5–6 months). Thereafter, solubility gradually declined. The values for solubility of proteins from mantle of both pota and octopus in 5% NaCl were greater in young specimens than in mature samples. There was no clear gender‐dependent tendency. The acid solubility of collagen also increased in most lots up to the sixth month, after which it characteristically began to decline. Pota collagen was significantly more soluble in mantles than in arms. In octopus mantle, collagen solubility gradually declined. In the sexually developed phases (immature and mature), no gender‐dependent differences were detected in the solubility of collagen from octopus mantle and arms. However, values did tend to be slightly higher in females. The mantles of immature specimens of pota and octopus were more suitable for freezing. © 2002 Society of Chemical Industry     

Antioxidant and functional properties of gelatin hydrolysates obtained from skin of sole and squid

Antioxidant and functional properties were evaluated for gelatin hydrolysates obtained from sole and squid skin gelatin by Alcalase, with a degree of hydrolysis of ∼35% and ∼50%, respectively. Both hydrolysates mainly consisted of peptides below 6.5 kDa, together with peptidic material from around 16 to 6.5 kDa. Moreover, the squid hydrolysate showed a peptide band of around 26 kDa. Antioxidant properties of both gelatins were highly increased by hydrolysis, especially ABTS and metal chelating abilities. The squid hydrolysate showed the highest antioxidant capacity by FRAP, ABTS and metal chelating assays in spite of the lower content in hydrophobic amino acids. Both gelatin hydrolysates had a good solubility (over 95%). The emulsifying activity index (EAI) decreased with increasing concentration. Conversely, the foam expansion increased with increasing concentration. However, both foam and emulsion stabilities were not apparently affected by the concentration of hydrolysate. In the case of the sole hydrolysate, which showed a lower degree Pro and Lys hydroxylation, foam stability was very poor, and 50% of foam expansion was lost after 5 min at all concentrations.     

Postbreakdown reanodization of tantalum

The scintillation phenomenon in anodic tantalum oxide has been studied by means of the potential rise during the reoxidation of samples which had undergone previous scintillation for a specified time. The information given by these curves, together with measurements of the dielectric properties, X-ray analysis and observation under the scanning electron microscope, allow two different processes to be distinguished during scintillation. The first stage of the scintillation is mainly characterized by a process of attack and partial healing of the oxide film with the formation of pores and microfissures. The second stage of scintillation is dominated by the process of field crystallization which irreversibly degrades the oxide's dielectric properties. The influence of the anodization parameters, such as current density and nature and concentration of the electrolyte, on the above processes is also investigated.Part of this work has been presented to the 8th International Vacuum Congress and the 4th International Conference on Solid Surfaces, Cannes (1980).     

Finite line-source model for borehole heat exchangers: effect of vertical temperature variations

A solution to the three-dimensional finite line-source (FLS) model for borehole heat exchangers (BHEs) that takes into account the prevailing geothermal gradient and allows arbitrary ground surface temperature changes is presented. Analytical expressions for the average ground temperature are derived by integrating the exact solution over the line-source depth. A self-consistent procedure to evaluate the in situ thermal response test (TRT) data is outlined. The effective thermal conductivity and the effective borehole thermal resistance can be determined by fitting the TRT data to the time-series expansion obtained for the average temperature.     

The synthesis of nickel nanoparticles by hydrazine reduction

A pure metallic nickel nanoparticle, spherical in shape, has been successfully synthesized by the chemical reduction of nickel chloride with hydrazine at room temperature without any protective agent and inert gas protection. The effect of nickel salt concentration and the molar ratio of hydrazine to Ni²⁺ on the properties of the resultant products were investigated by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). Also, the reaction mechanism is discussed in this paper. This synthetic method is proven to be simple and very facile. In addition, it is very interesting to note that the obtained nickel nanoparticle can be isolated in the solid state and stabilized for several months in the atmosphere.     

α-particle emission probabilities in the decay of U

²³⁵U decays by α-particle emission to ²³¹Th. The decay scheme of this nuclide is very complex, with more than 20 alpha branches. Recommended values for P_α of this nuclide are based on measurements carried out in 1975. This work presents the results of new measurements made with Si detectors and sources of enriched uranium in the frame of the EUROMET 591 cooperation project. The use of improved measurement techniques and numerical analysis of spectra allowed a new set of P_α values for 13 lines with improved uncertainties to be obtained.     

Chilled Storage of Pressurized Octopus (Octopus vulgaris) Muscle

ABSTRACT: Samples were subjected to continuous and step-pulsed pressurization, in both cases at 7 and 40 °C. There was a reduction of microbial flora (total viable count and lactic bacteria) after pressurization and during storage at 2.5 to 3.0 °C, chiefly in the lot pressurized by step-pulse at 400 MPa, 40 °C. Pressure-induced modification of the microbial flora resulted in a lower level of nitrogenous compounds. Pressurization reduced autolytic activity, but shear strength values remained stable throughout storage. There was less drip loss in the pressurized lots at 7 °C that at 40 °C, and the WHC values decreased during storage. Shelf life of the pressurized octopus overall was 43 d longer than unpressurized.