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WATERMIX fluids are formulated to combine the lubricating properties of oil with the cooling properties of water. They are essentially blends of mineral oil, emulsifier, corrosion inhibitor and, possibly, biocide.

The purpose of this research is to show the evaluation of food hygiene knowledge and self‐reported behaviours of school children, assessment of children's attitudes towards food hygiene and evaluation of barriers to the adoption of appropriate food hygiene behaviours.

The food hygiene knowledge and self‐reported behaviours of pupils (4 and 14 years; Key Stages 1‐3 in the English system – or Scottish equivalent) were determined using age‐appropriate knowledge quizzes completed by 2,259 pupils across England, Scotland, Northern Ireland and Wales. Attitudes towards food hygiene and barriers to performing desirable hygiene‐related behaviours were established through semi‐structured interviews with 82 pupils who completed knowledge tasks in South East England.

Children generally had good knowledge of food hygiene. However, there were misconceptions about the nature of micro‐organisms and how they affect food. In addition, a lack of reminders and practical food activities, especially at Key Stage 2 (7‐11 years), coupled with poor hand‐washing facilities, meant that children did not always adopt desirable behaviours. Children gave suggestions for ways to help others to remember good practice.

The study identified areas of weakness in pupils' hygiene knowledge and understanding and has determined barriers to adoption of desirable behaviours at all times. It has also suggested ways in which food hygiene education could be made more engaging for pupils, and other methods to encourage good practice.

All methods of egg preservation aim to prevent the entry and growth of spoilage or pathogenic micro‐organisms which would make the egg unpalatable or dangerous to health. Although the contents of chickens' eggs are sterile on laying, the shell surface may be contaminated with many micro‐organisms — on average there may be 130,000 bacteria on the shell of an egg. Most of these organisms, which come from the nest litter or the bird's excreta, will spoil the egg but are not harmful to health, for example Pseudomonas fluorescens which causes ‘green rot’ and off‐odours if allowed to penetrate the egg and grow. Some of the contaminating organisms may be pathogenic, food‐poisoning bacteria such as Salmonella species, which are sometimes present in chicken droppings, but pathogens are very rare in chickens' eggs. Similar salmonellae have been implicated in numerous food‐poisoning outbreaks associated with duck eggs, as the aquatic environment of the duck encourages their growth and on no account should duck eggs be preserved.

Numerous problems have arisen in the application of freezing methods to the various types of food products. One problem is concerned with the determination of the direct effects of low temperatures upon the food itself and another problem is to determine the effects of low temperatures upon other factors which may in turn affect the quality of the food. We are especially interested in knowing the exact effects of freezing and other low temperatures upon the micro‐organisms associated with foods. Bacteria constitute the most significant group of micro‐organisms affecting the sanitation and keeping qualities of foods. Those bringing about the decomposition of food products, while they are many and vary greatly, depending upon the nature of the food, are chiefly organisms from the air, water and soil. The types of bacteria found in foods vary greatly in their action on the food and also in reaction or response to varying temperature conditions. The action of micro‐organisms on foods of high carbohydrate content results in fermentations, while the action of the micro‐organisms on foods of high protein content will result, chiefly, in putrefactive changes. The former type of change usually occurs at a more rapid rate, when conditions are favourable, but the latter change usually results in a more undesirable condition of the food. While certain types of bacteria grow best at temperatures well above human body temperatures and others even as low as the freezing point of water, a large majority of those found in foods and the ones normally responsible for the detrimental changes in foods, are active only between 50° and 100° F. It is this latter group which is most implicated in food spoilage and it is significant that this group will be most effectively suppressed by low temperatures. Bacteria are much less affected by low than by high temperatures. Cold alone does not kill most types of bacteria, but slows down their activities to such an extent that they multiply very slowly, if at all. Many bacteria will die off, however, when held at a temperature below that which permits growth and reproduction. Bacteria, generally speaking, will be more easily killed when frozen in pure water than when frozen in foods containing albuminous matter and fats. There are a few bacteria of the cold‐loving type, which may actually multiply and cause slow decomposition at temperatures of 0° C. or less, if substances in solution are present to depress the crystallising point of water. Cold not only retards the growth of bacteria by the direct physiological effect of slowing down the rate of metabolism, but also depresses bacterial activity through its effect on their water and food supplies. Bacteria cannot grow and multiply in a completely frozen or crystallised medium, since they are by nature aquatic and are unable to carry on their normal activities except in a liquid medium. There is no evidence that bacteria maintain a body temperature which would make water available from a completely frozen medium. Bacteria may only utilise food when it is in soluble form, and thus capable of diffusion through their semipermeable cell membranes. When the temperature is sufficiently low to cause the crystallisation of most of the water, the remaining constituents become relatively more concentrated and this will further suppress the activity of the bacterial cells by affecting their osmotic pressures. These effects are very similar to those of partial desiccation or drying. In the course of experimentation some very striking examples of bacterial resistance to low temperatures have been reported. Lactobacillus and aerobacter have been reported to survive in peas stored at −10° C. for two years; whilst bacteria of the genus Pseudomonas were reported to increase in numbers when stored at −4° C. In general it may be said that practically all pathogenic bacteria likely to be found in foods will die off rather rapidly at low temperatures. However, this should not be interpreted to mean that infected foods can be made safe by low temperatures alone. Among the disease producing bacteria transmitted through foods, those of special significance include the organisms and toxins of botulism, typhoid fever, the several organisms of food poisoning called ptomaine poisoning, belonging to the Salmonella group (Salmonella enteritidis, etc.), and various organisms causing infections of the general nature of dysenteries or summer complaints of infants and adults. Frozen foods present no greater threat of botulism than foods preserved by other methods, yet it has been shown that Clostridium botulinum spores may survive freezing at −16° C. for as long as 14 months. The vegetables when thawed become toxic in from three to six days. Experiments have shown that Clostridium botulinum in foods preserved by “quick freezing” and subsequent storage at temperatures below 10° C., show no toxin production for at least 30 days. The lower the temperature of storage the greater the protection against botulism. All foods in which Clostridium botulinum might be present, and which have not been thoroughly heated, should be refrigerated at or near the freezing point. All foods which may harbour the botulism organisms or toxins should be selected with special care, before they are frozen, and care should be taken to see that they are kept frozen until used by the customer. Frozen vegetables should be used immediately after thawing. Thawing and refreezing is always objectionable since such a practice leads to loss of quality, and since bacterial growth and activity may occur during the period of thawing. While the typhoid organisms (Eberthella typhosa) shows considerable variation in resistance to low temperatures, it has been shown that about 99 per cent. will be killed immediately by freezing. Temperatures below freezing apparently have little more effect than the freezing point temperature. Small numbers of the Salmonella and similar organisms of the food poisoning groups may survive in frozen foods for periods of several weeks. It has been shown, however, that no significant growth of activity of these organisms will occur if the foods are refrigerated at 5° C. (41° F.) or less. Moulds and yeasts are of relatively little importance in frozen foods, both from the standpoint of sanitation and food spoilage. While low temperatures will materially retard the rate of enzymatic changes within food products, there is evidence that such changes continue to take place in frozen foods, even considerably below the freezing point. These changes probably account, in part, for the fact that frozen foods once thawed, will decompose more rapidly than foods which have not been frozen.

Natural selection—survival of the fittest—is as old as life itself. Applied genetics which is purposeful in contrast to natural selection also has a long history, particularly in agriculture; it has received impetus from the more exacting demands of the food industry for animal breeds with higher lean : fat and meat : bone ratios, for crops resistant to the teeming world of parasites. Capturing the exquisite scent, the colours and form beautiful of a rose is in effect applied genetics and it has even been applied to man. For example, Frederick the Great, Emperor of Prussia, to maintain a supply of very tall men for his guards—his Prussian Guards averaged seven feet in height—ordered them to marry very tall women to produce offspring carrying the genes of great height. In recent times, however, research and experiment in genetic control, more in the nature of active interference with genetic composition, has developed sufficiently to begin yielding results. It is self‐evident that in the field of micro‐organisms, active interference or manipulations will produce greater knowledge and understanding of the gene actions than in any other field or by any other techniques. The phenomenon of “transferred drug resistance”, the multi‐factorial resistance, of a chemical nature, transferred from one species of micro‐organisms to another, from animal to human pathogens, its role in mainly intestinal pathology and the serious hazards which have arisen from it; all this has led to an intensive study of plasmids and their mode of transmission. The work of the Agricultural Research Council's biologists (reported elsewhere in this issue) in relation to nitrogen‐fixing genes and transfer from one organism able to fix nitrogen to another not previously having this ability, illustrates the extreme importance of this new field. Disease susceptibility, the inhibition of invasiveness which can be acquired by relatively “silent” micro‐organisms, a better understanding of virulence and the possible “disarming” of organisms, particularly those of particular virulence to vulnerable groups. Perhaps this is looking for too much too soon, but Escherichia coli would seem to offer more scope for genetic experiments than most; it has serotypes of much variability and viability; and its life and labours in the human intestine have assumed considerable importance in recent years. The virulence of a few of its serotypes constitute an important field in food epidemiology. Their capacity to transfer plasmids—anent transfer of drug resistance— to strains of other organisms resident in the intestines, emphasizes the need for close study, with safeguards.

The aim of this study is to measure the effectiveness of the “Bug Investigators” pack in improving children's knowledge about micro‐organisms, hygiene and antibiotics when it is used within the National Curriculum in junior schools.

Teaching, using the “Bug Investigators” pack, was given by Gloucestershire primary school teachers. Children's general knowledge about hygiene, micro‐organisms and antibiotics was measured by questionnaire before and after lessons using the pack. A sample of 198 children aged 10 and 11 years in eight primary schools completed the questionnaires before and after teaching. A focus group was held with teachers to explore their views after using the pack.

Children's knowledge improved in all topic areas. Improved knowledge was most significant for what antibiotics do and how to use them and the value of our own good bugs (27, 31 and 16 percent improvement respectively). Knowledge about how bugs spread and hand hygiene was excellent (88 and 90 percent) before the education, but there was still 4 percent improvement in these topics. An exploratory discussion with teachers disclosed that some worksheets on viruses and resistant bacteria were too advanced for junior schools.

The study in this paper was undertaken in schools with relatively high‐level four‐science attainment, which could affect generalisability of findings.

The “Bug Investigators” teaching pack was effective at improving knowledge about micro‐organisms, hygiene and antibiotic use; it should be used more widely by junior schools. It is now a recognised teaching resource. Increased awareness of hygiene and prudent use of antibiotics should lower school absenteeism and improve antibiotic use in this generation of future adults.

In the UK alone, approximately £2,000 million is spent each year on cutting fluids and oils. This is merely the cost of purchasing the material and does not include the sizeable sum required to pay for disposal of used fluids or any additives needed to support the fluids while in use.

A major difference between sterilised foods (canned and bottled) and foods preserved by other methods, such as dehydration and freezing, is that sterilisation destroys the micro‐organisms that would otherwise destroy the food, whilst the other methods of preservation create an environment hostile to the micro‐organisms present in the food. In practice, this makes packaging of foods to be sterilised much more critical than packaging of foods preserved by other means. Leakage of small quantities of water into packages of dehydrated foods, for example, will shorten the storage life of the product but, unless gross leakage occurs, immediate deterioration will not occur. With a sterilised food, even the penetration of a single bacterium into a package can bring about the almost immediate demise of the food because the environment inside the package is usually ideal for microbiological growth. Fig. 1 shows the typical effect of leakage on sterilised and dehydrated foods. The perfect seal necessary for sterilised foods has, historically, been the main reason for the slow introduction of flexible pouches for sterilised foods, but modern technology now permits adequate seals to be made in suitable flexible materials and these are playing an increasingly important role.

THERE are many well‐known instances in which a lubricant must be prevented from leaking from a bearing, not merely just to prevent waste but to prevent contamination or staining, e.g. in food factories where it may drip on to edible products (in fact to ensure safety in some cases food factories use lubricants that are harmless if eaten just incase), or in textile mills where drips of oil would stain materials.

The complex nature of soil bacteria makes it imperative that they be considered in any problem related to soil. This paper gives data obtained by Kansas State University from a research project credited in the U.S. as a new approach to corrosion. Most conclusions hitherto have been drawn from soil samples taken in undisturbed soil such as might be found along a pipeline right‐of‐way; this paper considers largely soil found in the pipeline ditch.