The Importance of Temperature

Read this extract from a leaflet about food safety.

Render the text.

Serious Illnesses and their Treatment

Learn one of the texts by heart to act it out in the classroom.

1) Read the text below and ponder on “Clean living – it’s enough to make you ill”.

In Britain, it is believed that asthma, which has doubled in children in the last 25 years, is due to air pollution. Certainly, the symptoms of wheezing and shortness of breath can be made worse by exposure to traffic fumes, however, the risk of getting asthma in the first place is highest in the least polluted parts of the country. Seeing air pollution as a cause of asthma would seem to be common sense, but in fact, there is no relationship between the two. In our modern hygienic world, we, and particularly children, are no longer exposed to the bacteria that helped build the immune system in previous generations.

As with asthma, there are two other allergic conditions – eczema and hay fever – that are twice as common as they were 25 years ago. The three conditions run in families and tend to be “ailments of the advantaged”. In other words, they occur more frequently in children born in professional households and are more likely in small rather than large families, where there tend to be fewer germs being passed from one sibling to another. The rise in these conditions since the war years coincides exactly with the sharp decline in major childhood diseases, like polio, diphtheria, whooping cough and measles. They are thus presumably the “price” that has to be paid for modern medicines and better social conditions.

LISTENING COMPREHENSION

1) You will hear a speaker on the radio talking about a virus called ebola. Listen and give equivalents to the following:

вызывать панику, распространяться в пределах, вызывать страх, вспышка, последующий, смертность, вызывать (быть источником), страшный (ужасный), отказывают почки и печень, бредить, впадать в кому, смертоносные вирусы, передаваться воздушно-капельным путём, заразиться через кровь.

2) Listen again and write down the answers:

What illness kills more people than meningitis?

In which part of the world does the ebola virus occur?

How many people died of ebola in 1976?

When was the last time that anyone died from ebola?

What is the first symptom of an ebola virus infection?

What organs are destroyed by the virus?

Roughly what percentage of its victims die from ebola?

What can be used to cure or treat it?

What is the most likely way that the ebola virus is spread?

What animal is immune to ebola?

How food poisoning is caused

Most food poisoning is caused by five groups of bacteria – Campylobacter, Salmonella, Clostridium, Listeria and Staphylococcus. Even small numbers of Salmonella cells can cause food poisoning but other types of bacteria have to be present in large numbers before they make food dangerous. In other words, they have been allowed to grow and multiply for a sufficiently long time to produce large numbers of cells.

If salmonella and Listeria are to cause problems, living cells of the bacteria have to be present in the food when it is eaten. Normal, but thorough, cooking should destroy these cells and render them harmless.

Staphylococci are different because they produce toxin (a poisonous chemical) when they are growing. Even though cooking may destroy the bacterial cells, it is unlikely to inactivate the toxin.

Food producers do their best to make sure that food is not contaminated with any food-poisoning organisms. But if some should be in food, the maintenance of a cold temperature can do a lot to minimize growth and therefore the risk of food poisoning.

The Food Hygiene (Amendment) Regulations 1990 require that, from April 1995, most short-life food must be kept at 5°C or colder after manufacture and throughout distribution and display. Keeping such a cold temperature required many food companies to buy better refrigeration equipment so, until April 1995, a temperature of no warmer than 8°C had to be maintained for those foods.

Although there is no law governing the performance of household refrigerators, you should use a thermometer to make your refrigerator is operating at 5°C or colder. Suitable thermometers are available in Sainsbury’s stores which sell freezer accessories.

Once food has cooled to 5°C or colder if any food poisoning bacteria are present most will grow only very slowly and it would take a long time for them to reach large enough numbers to cause a problem. But, if Listeria should be present, it will grow and multiply, even at refrigerator temperatures. And if the food is at 10°C, Listeria will grow more rapidly than any other organism.

Frozen foods are stored at -18°C throughout distribution and there is no possibility of bacterial cells growing and multiplying at that temperature.

But remember that neither chilling nor freezing kills all bacteria, so it is very important to keep chilled foods chilled and frozen foods frozen until they are used. Once they reach room temperature, bacteria become active again and food deterioration stars or resumes from where it left off.

2) Answer the questions:

How is Salmonella different from other bacteria?

How is Staphylococcus different from other bacteria?

How does refrigeration help to reduce the risk of food poisoning?

How did the law change in 1995?

What is important to remember about chilled and frozen foods?

Дата добавления: 2014-12-29