The food chain
Wheat to a loaf of bread
- On the farm- Seeds are planted in the soil which grow to become crops. At harvest, combine harvesters cut the crop, thresh it, and separate the seeds from the ears of wheat from the chaff.
- At the mill- The wheat seeds are broken up by the rollers that turn them into flour
- On the road- Transport is an important part of the food chain.Much of your food now travels many miles from where it is grown to you. Usually, the greater the distance, the less sustainable, because more energy is used.
- At the bakery-Bakers mix flour with water, fat and yeast to make dough. Protein in the flour mixes with water to make gluten. the yeast grows in the dough. As it grows, it ferments sugars from the flour and produces CO2. Gluten traps the CO2, giving the bread its characteristic feature. Bakers shape the dough, let it rise again and bake it.
- In the supermarket- The bread is chosen and bought
- Traditionally, manures and animal wastes are used by farmers to keep soils fertile. They put back nitrates removed by harvesting
- Now, many farmers use fertilizers manufactured by the chemical industry. The industry uses natural gas or oil, air and water to make inorganic nitrates on a large scale. The first steps produce ammonia which goes to make fertilizers.
Pests- Farmers protect their crops from insects, weeds and diseases
- Some pesticides are natural chemicals, such as pyrethrum for chrysanthemums.
- Another way is through natural chemicals
- All methods of pest control have advantages an disadvantages
Elements , such as hydrogen and carbon, are continually cycled. This means that elements are "re-used"
Farming for food- Intensive Farming
- Intensive Farming- Modern farming methods that try to grow the maximum crop or maximum number of animals per area of land
- Fertile soils- Manufactured fertilizers are often used to add nitrogen compounds to the soil.
- Fighting pests and diseases- Farmers spray their crops several times with pesticides
- The environment- Intensive farming means that food can be produced in a smaller area, giving more space for woods and wildlife areas. Farmers can control their usage of fertilizer, water, pesticide and fuels to minimize their harmful effects. BUT. Growing the same crop in the same field reduces the variety of wildlife. Pesticides kill the weeds and insects that are food for other things.Too much fertilizer harms. In wet weather, nutrients can be washed into streams where they cause water weeds to grow fast. This can choke the water and kill fish.
- Farming, food and consumer- Can bring down the cost of food, because of the large scale.The products are large and free of pests but can contain traces of chemicals
- Sustainability- Lots of energy for fertilizers. Depends on cheap fossil fuel energy. Not much recycling of elements. High food miles.
Farming for food- Organic Farming
- Organic Farming- Farming using natural fertilizers and limited use of pesticides and herbicides
- Fertile Soils- Organic farmers use manures instead of fertilizers, the dung produced by the animals is used to add nutrients. They also rotate their crops to keep the soil fertile
- Fighting pests and diseases- Organic farmers use natural predators to control pest- biological control. Crop rotation also prevents disease by breaking the life cycle of weeds and pests. Organic farmers also put up with some weeds, until harvest time when they are ploughed into the soil to make it fertile. Organic farmers are allowed to use small amounts of chemical pesticides.
- The environment- Most smaller fields used in organic farming have hedges around them. They help to stop the wind blowing away soil from ploughed fields. Hedges offer homes fro wildlife. But manuring and ploughing can wash nutrients away
- Farming, food and the consumer- Organic food may be smaller and more varied in looks. It also may be more expensive, more labour to produce them. Some people believe it is more healthy this way.
- Sustainability- Organic farmers recycle nutrients and produce less waste. Manures fertilize soils and straw fro cereal crops is used as bedding. They save on the cost of chemicals but pay more on labour
Preserving and processing food
- Preservatives (E200 series)- Used to stop mould or bacteria growing on foods e.g SO2 on dried fruit and nitrates on bacon and ham
- Antioxidants (E300 series)- Stops foods reacting with oxygen and going "off", often used to treat vegetable oils, dairy and potato products
- Colours (E100 series)- Used to enhance or replace natural colours lost during processing or storage, often used in sweets
- Flavourings (don't have E no.)- Added in small amounts to give foods a particular taste or flavour that was not naturally present or was lost in processing
- Sweeteners- Used to replace sugar in things like diet drinks and products. Sweeteners such as aspartame and saccharin are many times sweeter than sugar, so only small amounts are used
- Emulsifiers and stabilizers- Emulsifiers mix ingredients that would separate and stabilizers stop them from re-separating
E numbers show that food additives has passed safety tests and has been approved by the EU
The digestion of chemicals in food
- Food contains the chemicals that people need to stay alive
- Starch and cellulose (carbohydrate) are natural polymers, they are both long chains of glucose molecules but are linked in different ways. Glucose is made of hydrogen, oxygen and carbon atoms
- Proteins are also natural polymers, they are long chains of amino acids. Amino acids are made of carbon, hydrogen, oxygen and nitrogen. Each protein has a different number and arrangement of amino acid
- When you swallow, food passes from your mouth to your stomach. Then it moves to your small intestine
- Muscles in the gut wall squeeze food along. They also mix the food with the digestive juices. These juices are called enzymes
- This must happen because only small molecules can pass through the wall of the gut into your blood.This breaking down of the large molecules is called digestion
- Enzymes break down starch ( can't do cellulose) into glucose and proteins into amino acids
Risks from harmful chemicals
- Food gives pleasure and is vitals for life, but sometimes foods can be dangerous
- Moulds- Moulds growing on nuts and dried fruits can produce aflatoxins, which can cause cancer
- Cassava- Cassava is a root crop, which roots contain poisonous compounds. These compounds release the poisonous chemical cyanide. Shredding the roots and squeezing out the juice removes most of the toxins. Heating dries the flour and removes the left- over toxins
- Starchy foods- Cooking starchy foods at a high temperature can produce acrylamide. The reaction involves an amino acid reacting with glucose. High doses of acrylamide can cause cancer in animals and may harm peoples health
- Fungi- Most of the people who have died through eating mushrooms have eaten the death cap. Toxins in this variety damage the liver.
- Gluten- Gluten is a protein in wheat and barley. Gluten damages the small intestine in people who suffer an intolerance to this protein. Coeliac disease is the best-known form gluten intolerance
- Peanuts- Some people are allergic to particular proteins found in peanuts. These proteins are destroyed by cooking, so both fresh and cooked and roasted peanuts can an allergic reaction.
Diet and diabetes
- Obese people have put on so much weight that that it is a danger to their health. Obesity is mainly caused by eating too much and not taking enough exercise. Obesity increases the risk of heart diseases and other diseases, such as diabetes.
- Diabetes is the 3rd most common long term (chronic) disease in the UK (after cancer and heart disease). People with diabetes have high levels of glucose in their blood, unless they are treated. Their bodies can not use glucose properly. There are 2 types of diabetes- type 1 and type 2
- More likely to start in younger people, but can develope at any age
- It develops when cells in the pancreas (an organ that produces some hormones and digestive enzymes) that produce insulin ( a hormone produced by the pancreas, helps to control the level of glucose in the blood) are destroyed.
- This type of diabetes is controlled with insulin injections
Diet and diabetes 2
Type 2 diabetes
- Type 2 diabetes is usually diagnosed in older people- the older you are, the greater the risk. But more young people are developing type 2 diabetes
- The pancreas of a person with type 2 diabetes can still make insulin. The problem is that the cells in the body no longer respond normally to the hormone. More insulin than normal is needed to keep blood glucose levels at the right level
- People with type 2 diabetes can sometimes be treated with diet and exercise
- Being over-weight is the leading risk factor for type 2 diabetes. The risk of developing type 2 diabetes increases by up to 10x in people with a BMI of 30+
- A lifestyle with little exercise is a risk factor for this diabetes. It is not because people who take little exercise are often over-weight, physical activity helps to control blood sugar levels
- 2 other risk factors are genetics and age. Type 2 diabetes tends to run in families. The risk of developing this diabetes in certain ethnic groups is about 5x higher.
Food and the consumer
- The European Union has passed laws covering the whole of the food chain. These laws are kept up to date. The EU has laws regulating-
- How farmers produce food
- How food is processed
- How food is sold
- What sort of information is on food labels
- National and local governmentsin the EU countries apply the EU's law's
The Food Standards Agency (FSA)
- The FSA was set up by parliament to protect public health and to defend the public interest in relation to food. The Agency aims to -
- Reduce the amount of illness caused by food
- Help people eat more healthily
- Promote honest and informative food labeling
- Promote best practice in the food industry
- Improve the enforcement of food law