Disruption of fat globules during concentration of whole milk in a pilot scale multiple-effect evaporator

The effects of heat treatment by direct steam injection (DSI) and concentration of whole milk using a pilot scale multiple-effect evaporator on fat globule size and the total milk fat globule membrane (MFGM) proteins were examined. In both nonpreheated and preheated whole milk, the size of milk fat globules decreased while the surface protein concentration of the fat globules increased as the milk passed through each effect of the evaporator. These results indicate that the fat globules were disrupted during DSI heating and evaporation and the proteins from the skim milk were adsorbed onto the fat globule surface.     

Catchment Afforestation and Water Supply in Strathclyde Region

The intensive afforestation of the uplands in Strathclyde Region, encouraged by Government policy, has given rise to growing concern about the impact of this significant change in land use on the quality and quantity of water supplies.
The smaller high-quality upland sources, which historically have minimal treatment, are those most at risk from changes as a result of forestry activity. Problems caused by a reduction in yield at some sources in the Region are discussed. A number of afforested water-supply catchments have been monitored since 1984 with the aim of identifying trends in water quality, and the results indicate increases in colour, turbidity, acidity and aluminium in supplies after activities such as access road construction, ploughing and draining. Evidence is presented of the continued leaching of phosphate more than six years after the application of fertilizer.
To enable improved advance consultation and planning to protect public water supplies, there is a requirement to be able to indicate the likely sensitivity of individual supplies to the various effects of afforestation.
The Region is committed to a substantial ten-year capital expenditure programme to upgrade water-treatment works to comply with the recent European Community (EC) water-supply standards imposed in 1985. Any significant long-term changes in water quality associated with forestry activity will make this programme more costly to achieve.     

Improved specimen holders for the scanning electron microscopy of insects and other small objects

Two specimen holders for use in scanning electron microscopy (SEM) of insect and other specimens glued to triangular cardboard points are described. They have important advantages over standard metal stub mounts. Diverse, precisely orientated, viewing angles are possible using single specimens, which can afterwards be re-pinned for return to the collection.     

INACTIVATION OF THE BSE AGENT

Bovine spongiform encephalopathy (BSE) belongs to a distinct group of transmissible degenerative encephalopathies (TDE) that includes scrapie in sheep and Creutzfeldt-Jakob disease (CJD) of humans. These fatal neurological diseases are caused by unconventional but uncharacterized transmissible agents that have a number of unusual properties; this includes a high degree of resistance to inactivation. The only disinfectant that appears to be completely effective against high titres of TDE infectivity is sodium hypochlorite. Exposure to 1 to 2 M sodium hydroxide has a substantial but incomplete effect, as does autoclaving at temperatures between 132 and 138C for up to an hour; however, a combination of 2 M sodium hydroxide and autoclaving, even at the more modest temperature of 121C for 30 min, appears to be completely effective. With lower titres of infectivity, less rigorous regimes may be effective. For example, although most of the rendering procedures used to manufacture meat and bone meal (MBM) throughout the European Union (EU) have been found to be incapable of inactivating BSE and scrapie agents, one method which appeared to be effective with moderate titres of BSE and scrapie agent, involved exposure to steam at 133C for 20 min. This procedure is now the only one approved within the EU for the manufacture of MBM for feeding animals, excluding ruminants; however, the UK has introduced a ban on feeding MBM to any farmed species because of the occurrence of a new variant form of CJD in the UK which appears to have been caused by the BSE agent. Although the clinical signs of scrapie in sheep are entirely attributable to neurological dysfunction, tissues such as spleen and lymph nodes are known to become infected before those of the central nervous system. In contrast, the only tissues which have been found to become infected in cattle with natural BSE are brain, spinal cord and retina. These are no longer used in animal or human foodstuff. Because scrapie agent has no known association with human disease there has been no restriction in the past on using any sheep tissues, including brain, as human food; however, it is known from experimental studies that the BSE agent can infect sheep by the oral route to cause a disease that is clinically and neurohistopathologically indistinguishable from scrapie. It is also known that the spleen becomes infected in such sheep. Sheep in the UK could theoretically have become infected with the BSE agent through the feeding of infected MBM before the feed-ban in 1988. There are now measures in place that prevent the head, spinal cord, and spleen of sheep being incorporated into foodstuff.     

On various types of decoupling for time-varying systems†

This paper deals with the problem of decoupling a class of linear time-varying multi-variable systems, based on the defining property that the impulse response matrix of a decoupled system is diagonal. Depending on the properties of the coefficient matrices of the vector differential equation of the open-loop system, the system may be uniformly or totally decoupled. The necessary and sufficient conditions that permit a system to be uniformly or totally decoupled by state variable feedback are given. The main contribution of this paper is the precise definition of these two classes of decoupling and a rigorous derivation of the necessary and sufficient conditions which show the necessity of requiring that the system be of constant ordered rank with respect to observability. A simple example illustrates the importance of having several definitions of decoupling. Finally, the results are specialized to the case of time invariant systems.     

The influence of substratum topography on bacterial adhesion to polymethyl methacrylate

The effect of substratum roughness on the adhesion of Pseudomonas aeruginosa and Staphylococcus epidermidis was investigated using PMMA. A small increase in Ra values (0.04–1.24 m) resulted in a significant increase (P<0.05) in bacterial attachment. Subsequent increases in surface roughness (Ra=1.86–7.89 m) resulted in a decrease in adhesion, although adhesion was still higher than to the smooth surface. When the PMMA surfaces were coated with protein (bovine serum albumin), no difference (P<0.05) could be determined in the amount of protein adsorbed, irrespective of surface topography. However, the influence of the underlying topography on adhesion was still evident. Substratum topography is an important parameter affecting bacterial adhesion to surfaces.     

Volatile Content and Sensory Attributes of Supercritical Carbon Dioxide Extracts of Cooked Chicken Fat

Volatile and sensory profiles were generated for extracts of cooked chicken fat obtained with supercritical carbon dioxide at 10.3 MPa, 20.7 MPa, and 31.O MPa at 40°C. Volatiles (318 total) were quantitated and 77 were identified. Concentrations of total volatiles, 7 compound classes, and 63 individual compounds were affected by treatments, generally increasing with decreasing extraction pressure. All extracts had higher concentrations than unextracted control. Total volatiles were concentrated 12-fold. Six sensory notes differed by treatment. Chicken fat aroma and flavor intensities were greater for all extracts than control and increased as pressure decreased. Total volatiles, 5 classes, and 42 individual compounds correlated with chicken fat aroma and/or flavor.     

Ability of neonatal human Lactobacillus isolates to remove cholesterol from liquid media

The activity of a number of human intestinal strains of Lactobacillus acidophilus , including newly isolated neonatal strains, have been examined for their ability to remove cholesterol from liquid medium. In common with other authors we find that cholesterol will co-precipitate with deconjugated bile acids as pH falls to values less than 5.0. But we also report that for some strains removal of cholesterol can occur in the absence of bile and that co-precipitation at low pH values cannot account for all cholesterol removed. The activity is unlikely to be as a result of bacterial cholesterol oxidase or dehydrogenase but may be one of physical association with the bacterial cell surface.