The effect of cooling rate on beef tenderness: The significance of pH at 7 °C

To study the effects of cooling regime on beef tenderness, seven commercial beef slaughterhouses with different cooling regimes were selected to obtain different carcass cooling rates. The pH values and temperatures of 8 M. longissimus dorsi (LD) and M. semimembranosus (SM) muscles from each slaughterhouse were monitored for 30 h. The muscles of the monitored carcasses were excised and vacuum packed for Allo-Kramer shear force (SF) determinations. Samples were kept at 3-4 °C for 5 or 21 d. The slaughterhouses were grouped by their average pH values of the muscles, prevailing at the moment when the temperature of the muscles reached 7 °C. The pH groups for LD were (i) low (5.52-5.63), (ii) medium (5.84-5.97) and (iii) high (6.16-6.17). The highest shear forces were in group (iii), being the toughest: 155-152 N/g, and the lowest in group (i) (the most tender): 108-116 N/g, respectively. The regression equation or the shear force was SF=-295.4+73.0?(pH at 7 °C); (R(2)=87%). There was no significant correlation between the cooling rate and tenderness in SM, indicating that it is difficult to control the tenderness of all muscles using the same cooling regime. The ageing effect was more marked and the variation in the shear forces smaller in the slaughterhouses generating carcasses with low pH values at 7 °C than in those generating high ones. It was concluded that a low cooling rate, or more specifically, the temperature/pH at the onset of rigor mortis, is important for beef tenderness. The pH of LD must fall to values below 5.7 before/when the temperature reaches 7 °C.     

Salmonella spp. shedding by alberta beef cattle and the detection of Salmonella spp. in ground beef

Breeder cows, cattle recently arrived at feedlots, and cattle about to be shipped for slaughter were tested for Salmonella spp. No Salmonella spp. were detected in fecal samples from breeding cows. Nineteen of 1,000 (1.9%) fecal samples from recently arrived feedlot cattle were positive for Salmonella spp. compared to only 2 of 1,000 (0.2%) fecal samples taken within 2 weeks of slaughter. The positive fecal samples were collected in 5 of 50 (10%) "recent arrival" pens tested and in 1 of 50 (2%) pens tested within 2 weeks of slaughter. The serotypes isolated were Salmonella Agona, Salmonella Enteritidis, Salmonella Typhimurium DT104, and Salmonella 4,5,12:i:-. Ground beef samples purchased from retail outlets throughout Alberta were processed for Salmonella spp. Thirteen of 1,002 (1.3%) samples were positive for Salmonella spp. The serotypes isolated from ground beef were Salmonella Anatum, Salmonella Heidelberg, Salmonella Montevideo, Salmonella Typhimurium, Salmonella Typhimurium var. Copenhagen, and Salmonella Rough-O:i:1,2. The antibiotic resistance and pulsed-field electrophoresis gel macrorestriction patterns of all isolates were compared.     

Requirements for transportation of fast pyrolysis bio-oil in Finland

The purpose of this paper is to discuss the requirements and challenges of pyrolysis oil's transportation in Finland. Pyrolysis oil is a new type of renewable liquid fuel that can be utilised in applications such as heat and electricity production. It has never been transported on a large scale in Finland. Possible options are transport by road, rail and waterway. The most significant requirements in its transportation are created by acidity and high density of pyrolysis oil, which impose requirements for the materials and transport equipment. The study described here shows that constant domestic transportation of pyrolysis oil is most reasonably operated with tank trucks. Rail-based transport may have potential for domestic fixed routes, and transport by water could be utilised in exporting. All transportation methods have limitations and advantages relative to each other. Ultimately, the production site and end-user's locations will determine the most suitable transport method.     

CO2 sorption and diffusion in polymethyl methacrylate–clay nanocomposites

This study reports the glass transition temperature (T_g), and sorption and diffusion of subcritical CO₂ gas in polymethyl methacrylate (PMMA) nanocomposites containing organically modified smectite clay, Cloisite 20A (C20A). A range of methods for preparing the PMMA‐clay nanocomposites was investigated and a solution coprecipitation method was selected as the most appropriate. Using this method, PMMA nanocomposite containing 2, 4, 6, and 10 wt% nanoclay loadings were prepared. Wide‐angle X‐ray diffraction (XRD) analysis and scanning electron microscopy (SEM) indicated that the 2 wt% nanocomposite materials had a well‐dispersed intercalated clay structure. The T_g for PMMA‐C20A nanocomposites, as measured by differential scanning calorimetry (DSC), was found to be independent of the clay loading. CO₂ solubility studies from 0 to 65°C and pressures up to 5.5 MPa using an in situ gravimetric technique were performed on compression‐molded films. The organoclay was found to have no effect on the solubility of CO₂ in PMMA, and therefore the solubility of CO₂ in the nanocomposite can be determined from the solubility of CO₂ in the matrix polymer alone. Diffusion coefficients were determined using the appropriate transport models for these test conditions and the diffusion coefficients for CO₂ in PMMA‐C20A composites were found to increase with organoclay loading. It is believed that the processing path taken to prepare the nanocomposites may have resulted in the agglomeration of the C20A organoclay, thereby preventing the polymer chains from fully wetting and intercalating a large number of clay particles. These agglomerations are responsible for the formation of large‐scale holes within the glassy nanocomposite, which behave as low resistance pathways for gas transport within the PMMA matrix. POLYM. ENG. SCI., 45:904–914, 2005. © 2005 Society of Plastics Engineers     

Microchip sonic spray ionization

The first microchip version of sonic spray ionization (SSI) as an atmospheric pressure ionization source for mass spectrometry (MS) is presented. The microchip used for SSI has recently been developed in our laboratory, and it has been used before as an atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) source. Now the ionization is achieved simply by applying high (sonic) speed nebulizer gas, without heat, corona discharge, or high voltage. The microchip SSI was applied to the analysis of tetra-N-butylammonium, verapamil, testosterone, angiotensin I, and ibuprofen. The limits of detection were in the range of 15 nM to 4 microM. The technique was found to be highly dependent on the position of the chip toward the mass spectrometer inlet, and on the gas and the sample solution flow rates. The microchip SSI provided dynamic linearity following a pattern similar to that used with electrospray, good quantitative repeatability (RSD=16%), and long-term signal stability.     

Microchip for combining gas chromatography or capillary liquid chromatography with atmospheric pressure photoionization-mass spectrometry

We present a microfabricated nebulizer chip for combining atmospheric pressure photoionization-mass spectrometry (APPI-MS) with gas chromatography (GC) or capillary liquid chromatography (capLC). The chip consists of a silicon plate and a glass plate or two glass plates. The chip includes a sample inlet channel, auxiliary gas and dopant inlet, vaporizer channel, nozzle, and platinum heater. The sample eluted from the capLC or GC is mixed with auxiliary gas and dopant (toluene) in the heated vaporizer. The chip forms a confined jet of the sample vapor, which is photoionized as it exits the chip. The analytical performance of GC- and capLC-microchip APPI-MS was evaluated with some polycyclic aromatic hydrocarbons, amphetamines, and steroids. The GC-muAPPI-MS method provides high sensitivity down to 0.8 fmol, repeatability (RSD = 7.5-14%), and linearity (r = 0.9952-0.9987). The capLC-muAPPI-MS method shows high sensitivity down to 1 fmol, good repeatability (RSD = 3.6-8.1%), and linearity (r = 0.9989-0.9992).     

Modelling of kinetics and mass transfer in the hydrogenation of xylose over Raney nickel catalyst

This paper discusses the modelling of xylose hydrogenation kinetics over Raney nickel in aqueous solutions, the determination of the hydrogen solubility in the reaction mixture as well as evaluation of mass transfer effects in the reaction system. The hydrogenation experiments were carried out batchwise in an automatic laboratory‐scale reactor. The reactor system operated at a pressure range of 40–70 bar and at temperatures between 80 and 140 °C. The catalyst‐to‐xylose ratio was approximately 5 wt‐% of the xylose weight normally. The reactor contents were analysed off‐line with a high performance liquid chromatograph. Hydrogen solubility in the reaction medium was determined with a gas‐chromatographic system. The solubility was found to remain fairly constant during the hydrogenation. Only a slight increase in the hydrogen solubility was detected as xylose was hydrogenated to xylitol. The overall hydrogen solubility in the reaction mixture was significantly lower than in pure water, as expected. The main hydrogenation product was xylitol, but small amounts of xylulose and arabinitol were detected as by‐products. A semi‐competitive kinetic model, based on hydrogen and xylose adsorption, was developed. The model accounts for the very different areas covered by a hydrogen atom and an organic species on the catalyst surface. The parameters of the kinetic model were determined with non‐linear regression analysis. It turned out that the kinetic model is able to describe the formation of both xylitol and the by‐products. The mass transfer effects in the batch hydrogenation were evaluated by using measured viscosities and estimated diffusion and mass transfer coefficients. A process simulator, utilizing the kinetic and mass transfer effects, was developed to predict the behaviour of industrial reactors. © 1999 Society of Chemical Industry     

Carotenoid Composition of Invertebrates Consumed by Two Insectivorous Bird Species

Dietary carotenoids are important pigments, antioxidants, and immune-stimulants for birds. Despite recent interest in carotenoids in bird ecology, we know surprisingly little about the carotenoid content of invertebrates consumed by birds. We compared carotenoid (lutein, β-carotene, and total) concentrations in invertebrates brought to nestlings by two insectivorous passerines, the great tit, Parus major and the pied flycatcher, Ficedula hypoleuca. We also compared carotenoid levels between environments that were either polluted by heavy metals or were not polluted, because the carotenoid-based plumage color of P. major nestlings is affected by environmental pollution. Lepidopterans were the most carotenoid-rich food items and contained the largest proportion of lutein. There were no differences in carotenoid concentrations in the food items of the two bird species but P. major nestlings obtained more carotenoids from their invertebrate diet than F. hypoleuca nestlings because the P. major diet had a higher proportion of lepidopteran larvae. In polluted areas, P. major nestlings consumed lower levels of dietary carotenoids than in unpolluted areas because of temporal differences in caterpillar abundance between polluted and unpolluted sites. Our study suggests that pollution-related difference in nestling plumage color in P. major is related to varying dietary proportion of lutein-rich food items rather than pollution-related variation in insect carotenoid levels.     

3‐Heterocycle‐Phenyl N‐Alkylcarbamates as FAAH Inhibitors: Design,Synthesis and 3D‐QSAR Studies

Carbamates are a well‐established class of fatty acid amide hydrolase (FAAH) inhibitors. Here we describe the synthesis of meta‐substituted phenolic N‐alkyl/aryl carbamates and their in vitro FAAH inhibitory activities. The most potent compound, 3‐(oxazol‐2yl)phenyl cyclohexylcarbamate ( 2 a ), inhibited FAAH with a sub‐nanomolar IC₅₀ value (IC₅₀=0.74 nM ). Additionally, we developed and validated three‐dimensional quantitative structure–activity relationships (QSAR) models of FAAH inhibition combining the newly disclosed carbamates with our previously published inhibitors to give a total set of 99 compounds. Prior to 3D‐QSAR modeling, the degree of correlation between FAAH inhibition and in silico reactivity was also established. Both 3D‐QSAR methods used, CoMSIA and GRID/GOLPE, produced statistically significant models with coefficient of correlation for external prediction (R²_PRED) values of 0.732 and 0.760, respectively. These models could be of high value in further FAAH inhibitor design.