Номер 3, страница 62 - гдз по английскому языку 10 класс (starlight) учебник Баранова, Дули

Module 2. Food & Health. Unit 2.14. Curricular cut - номер 3, страница 62.

Условие.

К этому заданию есть аудио

3 Do the quiz. Read and listen to check your answers.

1 Which of these pH numbers indicates an acid?

A 12 B 8 C 4

2 The thermometer in your fridge says 5°C.

You should

A turn it up.

B turn it down.

C leave it as it is.

3 To prevent bacteria from growing, food should be kept

A warm and moist.

B cold and dry.

C warm and dry.

4 Bacteria are destroyed by

A low temperatures.

B high temperatures.

C high acidity.

5 What is the ideal temperature for a home freezer?

A 0°C B -18°C C -72°C

Why does food go bad?

bacteria + air + warmth = spoilt food

FOOD & ACIDITY

The pH scale, which ranges from 1 to 14, measures whether something is an acid or an alkali. A solution with a pH value under 7 is an acid whereas a solution with a pH value of more than 7 is an alkali. Anything with a pH value of 7 is considered neutral. For example, citrus fruits, which have a pH value of about 2, are acidic, while pure water is neutral. The acidity of food is important because it affects the taste and the rate at which microorganisms grow in the food.

FOOD & MICROORGANISMS

Moulds, yeasts and bacteria are three types of microorganisms that cause food to spoil. Moulds are microorganisms made of spores that move through the air and land on food. We can avoid eating mouldy food because mould grows in colonies, so we can see it. Yeasts are single-celled organisms that can be found on the skin of fruit, which make fruit go bad. Bacteria are single-celled microorganisms which multiply by splitting in two. They are the most dangerous microorganisms because they are not visible to the naked eye. E.coli and salmonella are two deadly bacteria that can hide in food. They need warmth, moisture and time to grow on food, so we can prevent bacterial food poisoning by keeping dishes, surfaces and utensils clean, cool and dry.

OXIDISATION

Exposure to oxygen in the air also affects food. For example, an apple will quickly turn brown once it has been cut or peeled. This is because of a reaction between the natural proteins called enzymes in the fruit and the oxygen in the air. We can reduce this effect and stop food such as fruit and vegetables from turning brown by adding a natural acid (e.g. lemon juice), putting them in boiling water for ten seconds to destroy the enzymes or by preserving them in a sugary solution such as syrup.

TEMPERATURE

We can help food to stay fresh longer by either heating or cooling it. UHT products are termed ‘long-life’ because they are ultra-heat treated. This means they are heated to a temperature of about 149°C for 6-9 seconds and then quickly cooled. This destroys the bacteria. Keeping food in the fridge at 0°C - 3°C will slow the growth of bacteria and keep food fresh for longer. Freezing food at -18°C or lower keeps bacteria dormant. We should always make sure that we heat frozen foods to a temperature of 72°C or more to cook the food properly and kill any bacteria present. This way, we can avoid getting food poisoning.

Решение 1.

Решение 2.