Acceptability and storage stability of pork products with increased levels of polyunsaturated fatty acids

Several batches of back bacon, belly bacon, Dutch-style cervelat sausage, pork loin roll, shoulder with fat, Bologna, Guelders ring sausage, Saxon liver sausage and luncheon meat were produced with increasing PUFA-levels using raw materials containing up to 30% linoleic acid in their fats. Only the preparation of the high linoleic fermented Dutch-style cervelat sausages gave problems. Fatty acid composition did not change during preparation, nor during a two months' storage of back bacon at 15°C. Sensory evaluations of the products by an expert-panel revealed only a few differences, mostly related to consistency. Penetration measurements on luncheon meat showed an increase of softness as the PUFA-level was increased Products were stored for up to 61 days at 4 or 15°C. During storage, peroxide numbers and p-anisidine values were determined and sensory evaluations performed by an expert-panel. The unheated, and some of the pasteurised, highly unsaturated products appeared to be very susceptible to lipid oxidation.     

Effect of citric acid and citrate on the shelf stability of canned liver paste processed at reduced F(0) values

Citric acid and the combination of citric acid and citrate, in a few cases enriched with potassium sorbate, were tested for their stabilizing effect in a canned liver paste processed at reduced F(0) values. pH values of the rest products ranged from 5·24 to 5·76; a(w) values varied from 0·950 to 0·972. F(0) values of 0·05, 0·30 and 0·85 were applied. Before sterilization, the paste doughs were contaminated with mixtures of bacterial spores. Heated packages were challenged by incubation at 30 and 55°C for up to about 2 years. Incubated packages with the standard formulation at an F(0) of 0·05 showed the first blown cans at 30°C after 24 days. Starting from this point, at this F(0) value products with a variable, but increased, bacteriological stability were observed. At an F(0) of 0·30 a perfectly stable product at 30°C was observed after addition of 0·14% w/w citric acid only (product pH 5·69). Moreover, all tested combinations of additives at F(0) values of 0·30 and 0·85 yielded stable products at this incubation temperature. At the higher F(0) value a clear effect with respect to delaying thermophilic spoilage was observed. The effect of the application of potassium sorbate-in combination with both other additives-at F(0) values of 0·30 and 0·85 proved to be negligible.     

Carrier Localization on the Nanometer-Scale limits Transport in Metal Oxide Photoabsorbers

Metal oxides are considered as stable and low-cost photoelectrode candidates for hydrogen production by photoelectrochemical solar water splitting. However, their power conversion efficiencies usually suffer from poor transport of photogenerated charge carriers, which has been attributed previously to a variety of effects occurring on different time and length scales. In search for common understanding and for a better photo-conducting metal oxide photoabsorber, CuFeO₂, α-SnWO₄, BaSnO₃, FeVO₄, CuBi₂O₄, α-Fe₂O₃, and BiVO₄ are compared. Their kinetics of thermalization, trapping, localization, and recombination are monitored continuously 100 fs–100 µs and mobilities are determined for different probing lengths by combined time-resolved terahertz and microwave spectroscopy. As common issue, we find small mobilities < 3 cm²V^-1s^-1. Partial carrier localization further slows carrier diffusion beyond localization lengths of 1–6 nm and explains the extraordinarily long conductivity tails, which should not be taken as a sign of long diffusion lengths. For CuFeO₂, the localization is attributed to electrostatic barriers that enclose the crystallographic domains. The most promising novel material is BaSnO₃, which exhibits the highest mobility after reducing carrier localization by annealing in H₂. Such overcoming of carrier localization should be an objective of future efforts to enhance charge transport in metal oxides.     

Morphology, mechanical properties and viability of encapsulated cells

The morphological and mechanical properties of encapsulated yeast cells (Saccharomyces cerevisiae) have been investigated by atomic force microscopy (AFM). Single living cells have been coated through the alternate deposition of oppositely charged polyelectrolyte (PE) layers. The properties of cells coated by different numbers of PE layers and from PE solutions of different ionic strength have been investigated. AFM imaging indicates an increase in PE coating stability when decreasing the solution ionic strength. The Young's moduli of the different examined systems have been evaluated through a quantitative analysis of force-distance curves by using the Hertz-Sneddon model. The analysis indicates an increase in hybrid system stiffness when lowering the ionic strength of the PE solution. An evaluation of the viability of encapsulated cells was obtained by confocal laser scanning microscopy (CLSM) measurements. CLSM analysis indicates that cells preserve their subcellular structure and duplication capability after encapsulation. By coupling AFM and CLSM data, a correlation between local stiffness and duplication rate was obtained.     

Effect of Heat Treatment on the Properties of AlCu26Si8

ABSTRACT

In this paper, in situ centrifugal casting was proposed to fabricate Al-26 wt.% Cu-7.8 wt.% Si FG pipe with the density of 3.5 g/cm³ and also the wear resistance of 0.0241g/mm². The casting mould is preheated to approximately 200°C to avoid chilling effects, segregation, porosity and compensation of the shrinkage of the alloy during the casting. The microstructure results show that the Al₂Cu content smoothly decreases from the outer layer to inner layer. Vickers hardness, coefficient of thermal expansion (CTE) and mechanical properties of the present FG pipe are measured to show the significant dependence of the microstructure. Furthermore, the heat treatment of the samples are conducted in boiling water (100°C) for 4.5 h to promote the formations of new Al₂Cu particles into the α–Al phase and consequently improve the hardness and CTE of the FG pipe.     

Mechanical and microstructural characteristics of meat doughs, either heated by a continuous process in a radio-frequency field or conventionally in a waterbath

Meat doughs, all having the same chemical composition, were pasteurised to a comparable heat intensity (calculated as Cook values: target level of 5 min at 100°C): (i) while flowing through a glass tube (inner diameter 50 mm) mounted in a special radio-frequency (27 MHz) heating section; (ii) after flowing unheated through the glass tube at the same rate and heated in a waterbath; and (iii) after sampling immediately after the pump and heated in a waterbath. The cooked products were sampled in the core and at the rim of the product for rheological (oscillation and uniaxial compression tests at small strain), fracture measurements (uniaxial compression tests at high strain) and microstructural evaluation (light microscopy and video image analysis). Additional core samples were used for a sensory evaluation (triangle tests) of the texture of the differently processed doughs. The fast heating rate (25-30 K/min) at a mass flow of the dough of 100 kg/h (mean velocity 0.014 m/s) during dielectrical pasteurisation affected the mechanical character, the microstructure and the triangle test results of core samples from the sausages, compared to heating in a waterbath. Flow of the unheated dough through the tube of the continuous processing equipment, followed by heating in a waterbath, had little effect on the results of the mechanical tests, the microscopical evaluation and the triangle tests. The radio-frequency heated products had both higher storage and loss moduli (were more firm), fractured at higher stress values and were considered more firm in the sensory evaluation. The microstructure of dielectrically heated versus other samples displayed a more open structure of the protein matrix with larger irregularly shaped fat particles that were surrounded by relatively thin and compact protein bridges. The effects of flow and heating method on the behaviour of rim samples were very similar to their effects on the core of the products. A comparison of the mechanical behaviour of core and rim samples only was significant for radio-frequency heated doughs. The rim samples had lower storage and loss moduli and fractured at lower stress values than the core samples. Micrographs of the dielectrically heated rim versus core samples displayed more orientation of connective tissue particles in the direction of flow and of elongated, larger and irregularly shaped fat particles. Probably, shear at the wall of the tube affected the characteristics of the rim samples. All heated doughs displayed hardly and cooking losses. The radio-frequency heated products always displayed a thin layer of moisture on their surface and occasionally a little fat separation.     

A novel class of potential prion drugs: preliminary in vitro and in vivo data for multilayer coated gold nanoparticles

Gold nanoparticles coated with oppositely charged polyelectrolytes, such as polyallylamine hydrochloride and polystyrenesulfonate, were examined for potential inhibition of prion protein aggregation and prion (PrPSc) conversion and replication. Different coatings, finishing with a positive or negative layer, were tested, and different numbers of layers were investigated for their ability to interact and reduce the accumulation of PrPSc in scrapie prion infected ScGT1 and ScN2a cells. The particles efficiently hampered the accumulation of PrPSc in ScN2a cells and showed curing effects on ScGT1 cells with a nanoparticle concentration in the picomolar range. Finally, incubation periods of prion-infected mice treated with nanomolar concentrations of gold nanoparticles were significantly longer compared to untreated controls.     

In vivo delayed-type hypersensitivity skin test anergy in human immunodeficiency virus type 1 infection is associated with T cell nonresponsiveness in vitro

In a cross-sectional study, the prevalence of delayed-type hypersensitivity skin test anergy (DTHA) was examined in 136 asymptomatic human immunodeficiency virus-infected participants in relation to immunologic and virologic parameters. DTHA was assessed with a multitest cell-mediated immunity skin test. Of the 136 participants, with a mean CD4 T cell count of 335 x 10(6)/L, 25 were anergic (18.4%). In the stepwise forward multivariate logistic regression models, after adjustment for CD4 T cell counts, depending on whether it was analyzed continuously or after dichotomization (20th percentile), both T cell reactivity to CD2 plus CD28 antibodies or to CD3 antibodies were the most predictive markers of DTHA (odds ratio, 0.80; 95% confidence interval, 0.67-0.94; and odds ratio, 2.97; 95% confidence interval, 1.1-8.3, respectively). This study shows a strong correlation between the decreased T cell responses in vitro and DTHA. Therefore, next to DTHA testing, T cell function assays may be useful to test immune reconstitution observed during antiretroviral treatment.     

Mechanisms through which high glucose concentration raises [Ca2+]i in renal proximal tubular cells

BACKGROUND: The basal levels of cytosolic calcium ([Ca2+]i) of renal proximal tubular cells of rats with streptozotocin-induced diabetes are elevated. It is possible that this phenomenon is mediated by the hyperglycemia, which may cause both increased calcium influx into and/or decreased calcium efflux out of these cells. METHODS: We examined whether high glucose concentration in vitro causes acute rise in [Ca2+]i of freshly isolated renal proximal tubular cells and explored the pathways that are involved in such an event. RESULTS: There were dose and time dependent increments in [Ca2+]i of renal proximal tubular cells exposed to high concentrations of glucose. A similar effect was observed with equimolar concentrations of mannitol or choline chloride but not urea. A substantial part of the rise in [Ca2+]i was inhibited when the media contained verapamil, nifedipine, amlodipine or ryanodine and when the cells were placed in a calcium free media. Inhibitors of G protein(s) (GDPbetaS or pertussis toxin), inhibitors of cAMP-protein kinase A pathway (RpcAMP or H-89), inhibitors of protein kinase C (staurosporine or calphostin) and inhibitor of Na+-H+ exchanger (HOE 694) blocked the rise in a dose dependent manner. High glucose concentration also caused a decrease in ATP content of these cells and a reduction in the Vmax of their Ca2+ATPase. CONCLUSIONS: The results are consistent with the formulation that the osmotic activity (cell shrinkage) of the high glucose concentration may activate a stretch receptor with subsequent stimulation of various cellular pathways including G protein(s), cAMP-protein kinase A and phospholipase C systems and calcium channels. Activation of these cellular pathways permits both calcium influx into renal tubular cells and mobilization of calcium from their intracellular stores. Further, a decrease in calcium efflux secondary to the reduction in the Vmax of Ca2+ ATPase may occur. It is possible that the rise in [Ca2+]i is critical for the stimulation of the events that lead to restoration of cell volume to normal.