U NIT 2 NUTRITION AND HEALTH

2.1FOOD AND NUTRITIONAL SUBSTANCES

MACRO-NUTRIENTS: Sugars Lipids Proteins Water MICRO-NUTRIENTS: Vitamins Minerals

NUTRIENTS: they are the substances we need for obtaining energy and for making our own living matter. There are two kinds of nutrients: MACRO-NUTRIENTS: they are the major components in food. MICRO-NUTRIENTS: they are substances which are present in small quantities in food but which are also necessary for us.

Sugars or carbohydrates: their main function is to provide energy. The most common sugars in our diet are starches. Fibre which comes from vegetables is also a sugar. It is necessary for helping the food to pass through the intestine. Lipids or fats: these have many functions, but the most important is to provide energy. They can be found in vegetable oils and in animal fats.

Proteins: these are necessary for building the matter that forms our cells. Water: it is a fundamental component of living matter.

Vitamins: these have many functions. We need very small quantities of these substances, but their absence causes serious disorders. Minerals: these are chemical elements that do not form a part of living matter by themselves but which we need in small quantities.

FOOD PYRAMID

2.2 ENERGY NEEDS

The energy value of a food is proportional to the energy that is released when the food is burnt. This energy 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.

Sugars and lipids are the nutrients which provide us energy. The human body stores both types of nutrients so as to be able to have constantly available energy reserves. Lipids contain far more energy than sugars. Basal Metabolic Rate (BMR) is the amount of energy which is consumed by human body when it is totally at rest and with a constant temperature.

2.3 A COMPLETE AND BALANCED DIET

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

Criteria for an adecuate diet: Food should provide just the right amount of energy for carrying out our activities and for the development of the body. Diet should supply sufficient proteins, vitamins and minerals. With regard to the distribution of the foods which provide energy, this should be done in accordance to:  Food rich in sugars → 50-60% of total number of calories  Food rich in fats → 25-30% of total number of calories  Food rich in proteins → 15-20% of total number of calories

Disorders caused by food: Obesity: The organism does not expel the excess sugars but transforms them into fats. The accumulation of fats in tissues is the cause of obesity. Anorexia: It is characterised by extreme thinness due to a lack of food. People with anorexia reject food. Bulimia: People with bulimia eat all the time without control and vomit almost immediately all that they have ingested.

2.4FOOD PRESERVATION

Ways of preserving food at home: Drying, salting and smoking. Refrigeration: Freezing

The oldest way of preservation are drying, salting and smoking. Refrigeration: Keeping foods in a cold environment. When the temperature is lowered, the action of micro-organisms is slowed down. Foods can be conserved for several days.

Freezing: Keeping foods in a cold environment (-10ºC). The action of micro- organisms is detained almost completely. Frozen foods can be kept for long periods of time provided that the cold chain is not interrupted. If a food defrost, it must not be frozen again, it must be eaten immediately or thrown away.

EXPLAIN REFRIGERATION AND FREEZING BY COMPARING THEM.

REFRIGERATIONFREEZING Keeping foods in a cold environment Keeping foods in a cold environment (-10ºC) The action of microorganisms is slowered down The action of microorganisms is detained almost completely Food can be conserved for several days Frozen foods can be kept for long periods of time provided that the cold chain isn´t interrupted

Industrial forms of preservation: Traditional forms of preservation Additives Sterilisation techniques

All the traditional forms of preservation are used in industry (but these processes are not always apt for all foods). Additives: They are various substances which are added to food in small quantities and following strict health standars. They have different functions: improve the flavour, improve the appearance… Preservatives: They are additives which make food last longer.

Sterilisation techniques: sterilisation consists of killing the micro-organisms in the food by heat. Pasteurisation consists of heating the food (milk) to 72ºC for 15 seconds.

Use-by date: It is the day or month after which the food can not be used. After this date, the food will not be at peak quality from a health standpoint.

2.5 FOOD TECHNOLOGY

Handling food: Besides industrial processes, it is necessary for people who handle food, both industrially and at home, to follow some recommendations: Be careful with personal hygiene. Wash your hands frequently. Use appropriate and clean clothes (a cap, an apron, a mask and gloves). Be careful with the hygiene of instruments used for working.

Professionals in the food industry receive the proper training to ensure they work appropriately. This training is necessary for them to obtain a food handler´s certificate.

New ways of obtaining food: One of the concerns of the food industry is to obtain the necessary amount of food to satisfy the demand. Different techniques have been developed to obtain food more efficiently than by using traditional methods.

Agricultural techniques: Use greenhouses in which it is possible to obtain up to three anual harvests for some vegetables. Use of pesticides and herbicides to prevent the crops from suffering the attack of insects or the presence of competitive weeds.

Intensive farming: These techniques meant that animals are fattened in relatively short periods of time by improving the feeding of animals and by selection of breeds with rapid growth.

Fish factory installations: In these installations is where various kinds of fish are reared. This mean that it is possible to obtain a good quality food in a short period of time by using species with different nutritional requirements.

Transgenic food: Advances in the knowledge we have of hereditary matters has brought about the appearance of a new generation of food, genetically modified food.

New bio-technological techniques and genetic engineering mean that it is possible to manipulate the genetic information of an organism. A bacteria, a plant or an animal can be created containing the normal genetic information of its species but also with new information in all the cells, these organisms are known as transgenic.

However, genetically modified foods are still being studied and they will not be generally used until it has been proven that they do not cause any undesirable side effect to the people who consume them.

VOCABULARY

Nutrients Calorie Basal Metabolic Rate (BMR) Additives Preservatives Use-by date Transgenic

Nutrients: they are the substances we need for obtaining energy and for making our own living matter. There are two kinds of nutrients: macro- nutrients and micro-nutrients. Calorie: It is the amount of heat required to increase the temperature of a gram of water by one degree centigrade. Basal Metabolic Rate (BMR): It is the amount of energy which is consumed by human body when it is totally at rest and with a constant temperature.

Additives: They are various substances which are added to food in small quantities and following strict health standars. They have different functions: improve the flavour, improve the appearance… Preservatives: They are additives which make food last longer. Use-by date: It is the day or month after which the food can not be used. After this date, the food will not be at peak quality from a health standpoint. Transgenic: It is a bacteria, a plant or an animal that is created containing the normal genetic information of its species but also with new information in all the cells using new bio-technological techniques and genetic engineering.

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