0. PREVIOUS CONCEPTS OF BIOLOGY

1. FOOD AND NUTRITIONAL SUBSTANCES1.1. Nutrients1.2. Groups of foods

2. ENERGY NEEDS2.1. The energy of foods2.1. Base Metabolic Rate (BMR)

3. A COMPLETE AND BALANCED DIET3.1. Criteria for an adequate diet3.2. Disorders caused by food

4. FOOD CONSERVATION4.1. Ways of conserving food at home4.2. Industrial forms of conservation

5. FOOD TECHNOLOGY5.1. Transgenic foods

6. DIET AND CULTURE

• How to calculate the calories in a diet

• The label

• The energy contained in food

• Analysis of boiled ham

• The Pizza Explorer

We must distinguish between function of nutrition, nutrition and feeding

When we talk about the function of nutrition we are referring to the

set of processes which interchange substances with the environment, the obtaining of nutrients, the sharing out of these nutrients throughout the body and the elimination of waste.

These processes were examined in the previous unit.

On the other hand, when we speak of nutrition we are referring to the set of processes through which the organism receives, processes and uses the substances which it obtains from food.

The term feeding should only be used for the taking and ingesting of food. It is a more limited concept that nutrition.

Nutritional substances are those chemical compounds which are found in food and which we use to obtain energy and to build the matter which goes to make up our cells.

NUTRITIONAL SUBSTANCES

GLUCIDS (also calledSUGARS

or CARBOHYDRATES)

LIPIDS OR

FATSPROTEINS WATER VITAMINS

MINERAL SUBSTANCES

NUTRIENTS

MACRO-NUTRIENTSThey are the majority components of food

MICRONUTRIENTSWe need very small quantities of these substances, but their

absence causes serious disorders.

GLUCIDS LIPIDS PROTEINS WATER VITAMINSMINERAL

SALTSFIBRE

MACRO-NUTRIENTS:

a.1.) Glucids or carbohydrates: their main function in the body is to provide energy. The most common glucids in our diet are starches which can be found in pulses, potatoes, etc., and simple sugars like glucose and saccharose.

Some examples of pulses: chickpeas, beans, …

a.2.) Lipids or fats: they have many functions, but the most important is that of providing energy. They are, together with proteins, which form the cellular membrane of the cells.

They can be found in vegetable oils (olive oil, sunflower oil, etc.) and in animal fats (lard, fat and butter).

a.3.) Proteins: these are necessary for building the matter that forms our cells. We can obtain proteins from foods which have an animal origin (meat, fish and eggs) and a vegetable origin (pulses, cereals, etc.)

a.4.) Water: it is a fundamental component of living matter.

We need to take three litres of water a day: one and half litres comes from food and the rest we must drink.

a.5.) Fibre which comes from vegetables is also a glucid. It is necessary for helping the food to pass through the intestine.

b) MICRO-NUTRIENTS

b.1.)The most well-known micro-nutrients are vitamins. We need very small quantities of these substances, but their absence causes serious disorders.

b.2.)Minerals are also micro-nutrients, chemical elements that we also need in small quantities. Examples: iron (blood), magnesium, sodium, potassium, phosphorous, fluoride, etc.

EXAMPLES OF VITAMINS

VITAMINS Foods where they are found

A( retinol) Carrots, spinach, parsley

B1 (thiamine) Eggs, peanuts, pulses

B6 (pyridoxine)Sardines and fresh anchovies, lentils

C (ascorbic acid)Kiwis, red peppers, citrus fruits

D (calciferol) Produced by the skin

1.2. Groups of foods

There are different ways of grouping together the food we need for a healthy diet: the “FOOD WHEEL” or the “FOOD PYRAMID” are some examples. They help us to choose the adequate food.

We are going to classify as Grande Covian did. He was a Spanish nutritionist. This classification divides food into six groups, according to both their origin and their nutrients.

The six groups are as follows:

GROUP 1. MILK, MILK DERIVATES AND EGGS

These are a source of proteins, vitamins and calcium.

GROUP 2. MEAT, POULTRY AND

FISH

Basically, these provide us with proteins.

GROUP 3. FATS AND OILS

These include animal fats like butter and vegetable oils. Eaten in moderation they

provide the lipids we need.

GROUP 4. CEREALS, PULSES, POTATOES

AND SUGARS

These provide proteins and glucids

Exercises 2,3,4,5 – page 81

GROUP 5. VEGETABLES

These are a source of vitamins and fibre

GROUP 6. FRUIT

These provide glucids, vitamins and fibre

2.1. The energy of foods

RESPIRATION is a chemical reaction that takes place in our cells. It releases energy, and the final result is carbon dioxide and water, exactly the same as a total combustion in the laboratory.CO2 is toxic and must be collected by the blood and expelled through the respiratory apparatus.

The energy value of a food is proportional to the energy that is released when food is burnt in presence of O2. The energy that is released is measured in CALORIES.

A CALORIE is the amount of heat required to increase the temperature of a gram of water by one degree centigrade.It is a very small unit and, therefore, when measuring food we generally us a multiple, the KILOCALORIE.

1 Kcal = 1000 calories

To express the energy value of a food we use the amount of kcal provided by a ration of 100g of the food.

So, we say that beef provides 240 kcal per 100 g.

• Glucids and lipids are nutrients which provide us with energy. The human body stores both types of nutrients. We store glucids in the liver and lipids (fats) in various parts of our body.

1g of glucids 4 kcal when it is burnt1g of lipids 9kcal when it is burnt

• However, both types of nutrients should be present in our diet in correct quantities.

• If our diet provides an excess of kcal, the organism will store the accumulated calories as fat OBESITY

2.2. Base Metabolic Rate (BMR)

It is the minimum amount of energy that we need daily to survive.

However, for daily activity we need much more energy.

How to calculate it:

Women: BMR = 655 + 9.6 W + 1.8 H – 4.7 A Men: BMR = 655 + 13.7 W + 5 H – 6.8 A Where: W= weight, in kilograms H = height, in centimetres

A = age, in years

**Exercises 1 and 3 page 83

An optimum diet is a complete and balanced diet, complete because it uses foods from each group and balanced because we eat the correct proportion of each food.

The diet varies in each person: the work, the age, illnesses,… and many other factors have influence on diets

To know if our diet is complete and balanced or not, we must use some criteria.

A COMPLETE AND BALANCED DIET (AUDIO):http://lgfl.skoool.co.uk/content/keystage3/biology/pc/learningsteps/ABDLC/launch.html

3.1.Criteria for an adequate diet

Diet should comply with the following key points:- Food should provide just the right amount of energy for carrying out our activities and

for the development of the organism. An excess or defect in this energy supply will be harmful.

- Diet should supply enough proteins, vitamins and minerals. Once again, an excess or defect in this energy supply will be harmful.

- With regard to the distribution of the foods which provide energy, this should be done as follows:

DISTRIBUTION OF FOOD

FOOD PROPORTION

Rich in glucids 55-60% of total number of calories

Rich in lipids 30% of total number of calories

Rich in proteins 15% of total number of calories

Other criteria to bear in mind:

We must eat 22 g of fibre a day which can be obtained from vegetables and fruits

You should not eat more than 3g of salt a day. Any excess may cause problems in the excretory apparatus and increases blood pressure.

Only 10% of calories should be obtained from simple glucids (sugars).

The maximum level of cholesterol per day is 300 g. An excess of this can cause serious problems in the arteries.

Combine animal and vegetable proteins.

However, as you know, the most serious problems are brought through malnutrition. A poor diet with little variation can cause serious illnesses.

MALNUTRITION: http://lgfl.skoool.co.uk/content/keystage3/biology/pc/learningsteps/MALLC/launch.html

ANOREXIA and BULIMIA are characterized by extreme thinness due to a lack of food. Both disorders have a psychological origin, but they develop differently.

Persons with anorexia reject food whereas people with bulimia eat all the time with no control and vomit almost immediately all that they have ingested.

3.1. Disorders caused by food

An excess of food intake, especially of energetic food such as sweets, soft drinks and junk food, causes OBESITY.The organism transforms the excess of glucids into fats. The accumulation of fats in tissues can cause this disorder. However, it is sometimes an endocrine problem.

4.1.Ways of conserving food at home

DRYING, SALTING AND SMOKING These are the oldest ways of conservation. These processes cannot be used for all foods, but they are often good solutions for keeping food in a good condition for a long time.

These processes prevent against the action of micro-organisms.

DRYING, SALTING AND SMOKING These are the oldest ways of conservation. These processes cannot be used for all foods, but they are often good solutions for keeping food in a good condition for a long time.

These processes prevent against the action of micro-organisms.

CODCOD SMOKED

SALMON

SMOKED

SALMON

FREEZING is more effective than refrigeration. In a domestic freezer the temperature is some10ºC below zero. At this temperature, the action of microbes is detained almost completely.Frozen foods can be kept for long periods of time.

FREEZING is more effective than refrigeration. In a domestic freezer the temperature is some10ºC below zero. At this temperature, the action of microbes is detained almost completely.Frozen foods can be kept for long periods of time.

REFRIGERATION consists on keeping foods in a cold environment. When temperature is lowered, the action of bacteria and fungi slow down. Foods can be kept refrigerated for several days.

REFRIGERATION consists on keeping foods in a cold environment. When temperature is lowered, the action of bacteria and fungi slow down. Foods can be kept refrigerated for several days.

4.2.Industrial forms of conservation

FOOD ADDITIVES

ADDITIVES are various substances which are added to food in small quantities and following strict health

standards. They have different functions, for example, to improve the flavour or the appearance of food.

PRESERVATIVES are additives which make food last longer. They are not toxic substances. One of the

most commonly used is common salt.

FOOD ADDITIVES

ADDITIVES are various substances which are added to food in small quantities and following strict health

standards. They have different functions, for example, to improve the flavour or the appearance of food.

PRESERVATIVES are additives which make food last longer. They are not toxic substances. One of the

most commonly used is common salt.

STERILISATION TECHNIQUES

STERILISATION consists on killing the micro-organisms in the food. There are different forms of sterilisation. One of the most widely-used process is PASTEURISATION,

which is frequently applied to milk. This consists on heating the milk to 80ºC for 30 seconds. This heating kills

99.5% of all the germs contained in milk.

STERILISATION TECHNIQUES

STERILISATION consists on killing the micro-organisms in the food. There are different forms of sterilisation. One of the most widely-used process is PASTEURISATION,

which is frequently applied to milk. This consists on heating the milk to 80ºC for 30 seconds. This heating kills

99.5% of all the germs contained in milk.

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HANDLING FOOD

People who handle foods, both industrially and People who handle foods, both industrially and at home, must follow a series of at home, must follow a series of recommendations to avoid the exposure of the recommendations to avoid the exposure of the food to micro-organisms, such as:food to micro-organisms, such as:

* Be especially careful with personal hygiene * Be especially careful with personal hygiene when working with food. Wash your hands when working with food. Wash your hands frequently and especially when you have used frequently and especially when you have used the toilet.the toilet.

* Use appropriate and clean clothes, a cap to * Use appropriate and clean clothes, a cap to cover your hair, an apron and, in some cases, cover your hair, an apron and, in some cases, a mask and gloves.a mask and gloves.

* Be careful with the hygiene of the * Be careful with the hygiene of the instruments used (knives, palettes,…)instruments used (knives, palettes,…)

- Professionals in the food Professionals in the food industries receive the necessary industries receive the necessary training to obtain a training to obtain a FOOD FOOD HANDLER’S HANDLER’S CERTIFICATECERTIFICATE..

HANDLING FOOD

People who handle foods, both industrially and People who handle foods, both industrially and at home, must follow a series of at home, must follow a series of recommendations to avoid the exposure of the recommendations to avoid the exposure of the food to micro-organisms, such as:food to micro-organisms, such as:

* Be especially careful with personal hygiene * Be especially careful with personal hygiene when working with food. Wash your hands when working with food. Wash your hands frequently and especially when you have used frequently and especially when you have used the toilet.the toilet.

* Use appropriate and clean clothes, a cap to * Use appropriate and clean clothes, a cap to cover your hair, an apron and, in some cases, cover your hair, an apron and, in some cases, a mask and gloves.a mask and gloves.

* Be careful with the hygiene of the * Be careful with the hygiene of the instruments used (knives, palettes,…)instruments used (knives, palettes,…)

- Professionals in the food Professionals in the food industries receive the necessary industries receive the necessary training to obtain a training to obtain a FOOD FOOD HANDLER’S HANDLER’S CERTIFICATECERTIFICATE..

NEW WAYS OF OBTAINING FOODSNEW WAYS OF OBTAINING FOODS

GREEN HOUSES

This technique allows to obtain up to three annual harvests for some vegetables.

The use of PESTICIDES and HERBICIDES is also common and these prevent the crops from suffering the attacks of insects or the presence of competitive weeds.

These chemical products improve the performance of crops but must be used carefully to avoid harming the environment.

GREEN HOUSES

This technique allows to obtain up to three annual harvests for some vegetables.

The use of PESTICIDES and HERBICIDES is also common and these prevent the crops from suffering the attacks of insects or the presence of competitive weeds.

These chemical products improve the performance of crops but must be used carefully to avoid harming the environment.

INTENSIVE FARMING

Techniques used in current farms means that animals are fattened in relatively short periods of time.

INTENSIVE FARMING

Techniques used in current farms means that animals are fattened in relatively short periods of time.

FISH FACTORIES

They are places where various kinds of fish are reared. It means that it is possible to obtain food in a short period of time and it avoids, up to a point, the over-exploitations of natural fishing resources.

FISH FACTORIES

They are places where various kinds of fish are reared. It means that it is possible to obtain food in a short period of time and it avoids, up to a point, the over-exploitations of natural fishing resources.

TRANSGENIC FOOD

The DNA, molecule found in all cells, contains the genetic information. Its composition determines all the characteristics which are inherited from parents to children.

New bio-technological techniques and genetic engineering mean that it is possible to manipulate the genetic information of an organism. By means of a very complex procedure, a fragment of DNA from a being, is introduced in the DNA of another being.

In this way, bacteria, a plant or an animal can be created with new information in all the cells. This plant or animal is known as TRANSGENIC.

The advantages of this technique when it is applied to food:

-For example, we can obtain a variety of tomato with a gen that produces a substance which repels insects

-Plants that are more resistant to diseases….

However, we can find some undesirable side effects to people who consume them, because transgenic foods are still being studied.

TRANSGENIC FOOD

The DNA, molecule found in all cells, contains the genetic information. Its composition determines all the characteristics which are inherited from parents to children.

New bio-technological techniques and genetic engineering mean that it is possible to manipulate the genetic information of an organism. By means of a very complex procedure, a fragment of DNA from a being, is introduced in the DNA of another being.

In this way, bacteria, a plant or an animal can be created with new information in all the cells. This plant or animal is known as TRANSGENIC.

The advantages of this technique when it is applied to food:

-For example, we can obtain a variety of tomato with a gen that produces a substance which repels insects

-Plants that are more resistant to diseases….

However, we can find some undesirable side effects to people who consume them, because transgenic foods are still being studied.

TOPICS TO DISCUSS:

The availability of food

Wheat, potato, rice and corn cultures

The importance of religion

The Mediterranean diet

Only meat or only vegetables?