Today we are going to cover: Food additives Harmfull chemicals in food Methods to keep food safe How to eat healthy Food Matters 21/03/11
Food additives There are 5 different types of food additives you need to be familiar with • Food colourings- these make food look mpore attractive and more appetising. Often used in soft drinks and sweets. • Flavourings and flavour enhancers- flavourings are added to a food to give it a new/ different taste. Flavour enhancers are added to food in order to enhance the original flavour the food had. Eg. Make a banana taste more like a banana. Usually found in ready meals.
3. Artificial sweetners(like saccharin) are used in things like dies foods and drinks. They usually taste sweeter than sugar, so you don’t need to use as much. 4. Antioxidants- these stop foods from reacting with oxygen and going off. Oxygen can turn fat in food into a nasty tasting and smelling substance. Antioxidants are added to food that contain fat. 5. Preservatives- These are added to food to stop harmful bacteria growing on them. Means food can be stored for longer.
Emulsifiers and Stabilisers (additives) These help oils and waters mix correctly. When oil is added to water they separate out. Emulsifiers are added to foods to help oil and water mix. Stabilisers keep the oil and water together once mixed. Emulsifiers and stabilisers are added to food which contain water and oil, For instance mayonnaise, salad dressing, vegetable spread (Flora).
Food additives are regulated Food additives are regulated by the Food Standards Agency. Food additives need to pass a safety test, to make sure they wont cause long term effects. If they pass they will be given an E number which means they have passed the standards set by the European union. E numbers do however still cause problems to some people. Allergic reactions, asthma and hyperactivity.
intolerances e.g. gluten (in wheat) Harmfull chemicals in food Allergies e.g. peanuts Certain fungi can grow on nuts and harvested cereal crops. These produce a toxin called Aflatoxin. Aflatoxin cannot be gotten rid of Cassava: If roots are eaten lethal cyanide in the liver is produced. Also the same can be said for red kidney beans if they are not cooked properly.
Difference between intolerance and allergy An Allergy is where a person gets an allergic reaction (e.g rash) when exposed to a particular food. Can cause windpipe to contract and lead to death. Example peanut allergy An Intolerance (example wheat) is where a person can eat a food, no reaction is shown, however person cannot digest the food.
Burning foods can also be bad Burning foods, or cooking foods at very high temperatures can cause dangerous chemicals, HAs and PAHs to be formed. These can alter your DNA, causing cancer. Chemicals left over from farming (pesticide residue) can also cause long term problems in humans (e.g. Parkinson's).
How can I avoid these harmful chemicals? FSA (food standards agency) is a safety watchdog responsible for: • clear labelling on foodstuffs, offers advice on food safety, diet farming and hygiene • Food sampling programmes, to check for harmful chemicals. Scientific advisory committees carry out risk assessments to set safe limits. These advise the government on what is safe to eat and what isn’t.
Eating healthy Individuals can make their own decisions on what they want to eat. People who want to reduce their exposure to potentially harmful chemicals can take several steps: 1)Choose food produced in a way which minimises the amount of artificial chemicals applied to it. 2) Wash the foods carefully 3)Store and cook the food in the way recommended on the packaging.
Danger of processed foods Processed foods contain high amounts of sugar, fat, salt and other additives. However a lot of processed foods are convenient and don’t take a lot of preparation or cooking.
Task: What could be going on here? Explain. • Robbie cooks fatty steaks on a BBQ. He puts a lot of coal in and gets a good flame going. • Bert is an eco warrior, he collects food from the forest to eat. • Flora has a rash and breathing problems when she eats peanut butter sandwiches.
C3 Revision lesson 2Today we will cover: Nitrogen cycle, Organic and intensive farming, natural polymers, digestion, insulin and diabetes.
Farming As plants grow they take in oxygen, nitrogen and carbon through their roots and leaves. When plants die and decompose most of these elements are recycles into the soil. If we farm (harvest) the plant and its products we are effectively removing this recycling ability. This is why farmers need to add nutrients to their soil to make sure that plants have enough nutrients to grow each year.
The nitrogen cycle The nitrogen cycle is a process which continues to recycle nitrogen within the environment. See Nitrogen cycle sheet.
Organic and intensive farming As we said removing crops removes potential nutrients from the soil. Organic farming products are generally more expensive in the supermarkets. This is because organic farming tends to require more manual labour.
Organic farming Organic farming relies on the farmer not using artificial fertilisers. They use natural substances instead, like animal manure, compost and even human sewage. Manure and sewage feed into the nitrogen cycle, being broken down by nitrifying bacteria.
Organic farming- (legumes) Some legumes (pea’sand clover) have root nodules on their roots. These root nodules contain Nitrogen fixing bacteria which can fix nitrogen from the air into nitrates in the soil. Organic farmers may use crop rotation, where for one year they may just grow legumes in one of their fields. These legumes will then add nitrates to the soil for them.
Intensive farming This method relies on artificial fertilisers which are produced in factories. These artificial fertilisers contain pure chemicals so it is easy to add just the right amount. They can also use small amounts as it is a pure chemical. Also because the fertilisers contain pure nitrates you don’t need to rely on the nitrifying bacteria.
Pest control- Intensive farming Pests and diseases are a pain for farmers. Intensive farming relies on chemicals such as pesticides and herbicides which kill pests and weeds. Fungicides are also used which kill fungi infections on the plants. Chemical pesticides kill all animals which could be classed as a potential pest, not just the ones you want killed. So you may end up killing pests that are beneficial in the future.
Pest control- Organic farming Organic farmers use biological control to kill pests on their crops. This is where you use a pests natural predator to get rid of the pest. For instance if a farmer has lots of aphids (green fly) on their crops they will use ladybirds to naturally hunt down and eat the aphids. Leaving hedge rows at the edges of field provides a home for these natural predators.
Organic farmers need to follow certain rules set out by the UK government. These say that they cannot use artificial fertilisers, chemicals, and pesticides. They also cannot use growth hormones on any of their plants or animals.
in C2 we have already met polymers… these huge molecules are made up of much smaller units during polymerisation
Polymers made from sugars sugars are molecules made of carbon, oxygen and hydrogen Cellulose Starch
Polymers made from amino acids Proteins: The monomers (amino acids) are made from carbon, oxygen, hydrogen AND nitrogen (shown by the blueatoms above!)
Digestion of food • natural polymers e.g. starch and protein are broken down to soluble sugars/ amino acids which can be transported in the blood Absorption of the sugars and amino acids occurs in the small intestine
What are the amino acids used for? • to build new proteins for growth and repair muscle Skin and hair haemoglobin
What happens if there are too many amino acids in our bodies? Kidneys remove the urea from the blood and send it to the bladder Excess amino acids are broken down to form Urea by the liver Waste is excreted
Sugars • Vital as an energy source for respiration • Found in large amounts in processed foods • Are absorbed quickly into the blood stream • Insulin (a hormone produced by the pancreas) controls the uptake of sugars into cells (so lowers blood sugar level!)
Blood sugar levels out of control Poor diet • A condition known as diabetes obesity Type 1 diabetes Type 2 diabetes Not enough insulin produced OR the body no longer responds to it Pancreas stops insulin production Requires regular injections of insulin Controlled by diet and exercise