Analysis of Isinglass Residues in Beer

A method has been developed for the detection of trace quantities of residual isinglass present in fined beers. Isinglass residues in beer are concentrated by means of an antibody raised using isinglass as an antigen. The separated isinglass is hydrolysed to its constituent acids and quantified by measuring the content of hydroxyproline. The limit of quantification of this method, that is the concentration of isinglass in beer which can be distinguished from background levels of hydroxyproline, is 0.17 mg of isinglass/litre of beer (on an isinglass dry weight basis). This method has been used to quantify the concentration of isinglass residues which could be present in brewery and cask conditioned beers, and also to determine whether there is likely to be stratification of isinglass residues in casks.     

Kernel lot distribution assessment (KeLDA): a study on the distribution of GMO in large soybean shipments

The reliability of analytical testing is strongly affected by sampling uncertainty. Sampling is always a source of error and the aim of “good” sampling practice is to minimize this error. Generally the distribution of genetically modified (GM) material within lots is assumed to be random in order to use binomial distribution to make inferences. This assumption was never verified in practice and no experimental data investigating the distribution of genetically modified organisms (GMOs) exist. The objectives of the KeLDA project were: (1) to assess the distribution of GM material in soybean lots (2) to estimate the amount of variability of distribution patterns among lots. The GM content of 15 soybean lots imported into the EU was estimated (using real-time PCR methodology) analyzing 100 increment samples systematically sampled from each lot at predetermined time intervals during the whole period of off-loading. The distribution of GM material was inferred by the one-dimensional (temporal) distribution of contaminated increments. All the lots display significant spatial structuring, indicating that randomness cannot be assumed a priori. The evidence that the distribution of GM material is heterogeneous highlights the need to develop sampling protocols based on statistical models free of distribution requirements.     

Post-mortem kinetics of meat tenderness and the components of the calpain system in bull skeletal muscle

Eight strip loins (M. longissimus dorsi) from pasture fed Friesian bulls were aged at 15 °C for a range of times from 1 to 120 h. pH declined from 6.29 (SE 0.119) one hour post slaughter to an ultimate pH of 5.48 (SE 0.013). The activities of the components of the calpain system (μ-calpain, m-calpain and calpastatin) were determined after separation on a DEAE-sephacel column. There was a dramatic decline in μ-calpain activity post slaughter with a complete disappearance within 48 h. The rates of decline in m-calpain and calpastatin activity were slower with 30% and 50% remaining 120 h post slaughter, respectively. The rapid decline in μ-calpain activity relative to the calpastatin activity is likely to reduce the degree of tenderisation and ultimate tenderness of the meat.     

1997 UK Total Diet Study dietary exposures to aluminium, arsenic, cadmium, chromium, copper, lead, mercury, nickel, selenium, tin and zinc

Concentrations of aluminium, arsenic, cadmium, chromium, copper, lead, mercury, nickel, selenium, tin and zinc were determined in samples from the 1997 UK Total Diet Study and used to estimate dietary exposures of the general UK population. Population average dietary exposures to aluminium (3.4mg/day), arsenic (0.065mg/day), cadmium (0.012mg/day), chromium (0.10mg/day), copper (1.2mg/day), mercury (0.003mg/day), nickel (0.13mg/day), tin (1.8mg/ day) and zinc (8.4mg/day) are similar to those from previous UK Total Diet Studies and are below the appropriate PTWIs, PMTDIs and TDIs. Dietary exposure of the UK population (0.026 mg/day) to lead is falling as a result of measures taken to reduce lead contamination of the environment and food and is well below the PTWI. There has been little change in UK estimates of selenium exposure since the 1994 Total Diet Study but current estimates (0.039mg/day) are lower than those derived from earlier Total Diet Studies.     

The effect of N fertilizer forms on nitrous oxide emissions from UK arable land and grassland

Nitrous oxide emission factors (EFs) were calculated from measurements of emissions from UK wheat crops and grassland, that were part of a wider research programme on N loss pathways and crop responses. Field studies were undertaken in 2003, 2004 and 2005??a total of 12 site-seasons. Nitrous oxide emissions were measured by the closed static chamber method, following the application of various N fertilizer forms (ammonium nitrate (AN), calcium ammonium nitrate (CAN), urea (UR), urea ammonium sulphate and urea ammonium nitrate) at the recommended rates. Emission factors for the growing season (March?CSeptember) ranged from less than 0.1?C3.9?%. In the 2nd year, measurements continued at three sites until the following February; the resulting annual EFs were one-third greater, on average, than those for the growing season. There was some evidence that N₂O emissions from UR were smaller than from AN or CAN, but when this was adjusted for loss of ammonia by volatilization, there was generally little difference between different forms of N. Emissions from UR modified by the addition of the urease inhibitor nBTPT (UR?+?UI) were lower than corresponding emissions from nitrate forms, except under conditions where emissions were generally low, even allowing for indirect emissions, suggesting that the use of a urease inhibitor can provide some mitigation of N₂O, as well as NH₃, emissions. The emission data broadly bear out the relationships obtained in earlier UK studies, showing a strong dependence of N₂O emission on soil wetness, temperature and the presence of sufficient mineral N in the soil, which decreases rapidly after N application mainly as a result of plant uptake. Overall net mean EFs for the whole season (after subtracting background emissions from unfertilized controls) covered a range wider than the 0.3?C3.0?% range of IPCC (2006).     

Response to Raymond Gibbs

Minds and Machines -     

The stiffness of skeletal muscle in isometric contraction and rigor: the fraction of myosin heads bound to actin

Step changes in length (between -3 and +5 nm per half-sarcomere) were imposed on isolated muscle fibers at the plateau of an isometric tetanus (tension T0) and on the same fibers in rigor after permeabilization of the sarcolemma, to determine stiffness of the half-sarcomere in the two conditions. To identify the contribution of actin filaments to the total half-sarcomere compliance (C), measurements were made at sarcomere lengths between 2.00 and 2.15 microm, where the number of myosin cross-bridges in the region of overlap between the myosin filament and the actin filament remains constant, and only the length of the nonoverlapped region of the actin filament changes with sarcomere length. At 2.1 microm sarcomere length, C was 3.9 nm T0(-1) in active isometric contraction and 2.6 nm T0(-1) in rigor. The actin filament compliance, estimated from the slope of the relation between C and sarcomere length, was 2.3 nm microm(-1) T0(-1). Recent x-ray diffraction experiments suggest that the myosin filament compliance is 1.3 nm microm(-1) T0(-1). With these values for filament compliance, the difference in half-sarcomere compliance between isometric contraction and rigor indicates that the fraction of myosin cross-bridges attached to actin in isometric contraction is not larger than 0.43, assuming that cross-bridge elasticity is the same in isometric contraction and rigor.