The aim of this experiment is to identify different food groups within several different unknown solutions. This will be carried out by placing the unknown solutions into separate test tubes and using different chemical indicators to see if any reactions occur. Each food group will act different when the chemical indicator is added, some will change colour while others will separate.
Food is a vital source of energy that is needed for survival, without this energy source our bodies wouldn’t be able to function. All food can be broken down into various food groups such as water, proteins, carbohydrates, vitamins, fats, fibre and minerals. Our bodies need all of these food groups to function with each of them playing a specific role. These food groups are present in our every day food and are taken into our body through a process of digestion. The food is chewed up and broken down into smaller bits in the mouth and then travels down to the stomach where it is broken down further by the hydrochloric acid in the stomach in a process called chemical digestion. Once the food has been broken down it is then absorbed by the blood to provide the various functions that our body needs to survive. We can get some of these food groups by other means such as vitamin injections, tablets or food supplements. These are generally taken when our bodies are not able to break down certain foods down, have allergies or vegetarians. There are many different ways we can test food for the presence of certain substances within the food we eat. To test for carbohydrates or sugar in food a liquid called Benedict’s reagent is used, Benedict’s reagent contains sodium citrate, sodium carbonate and copper sulphate. Benedict’s reagent is mixed with a sample of food and then heated, if any reducing sugars such as glucose are present it will produce a precipitate. Depending on the amount of reducing sugar present the colour will change from yellow to brick red, the darker the precipitate goes the more concentration of sugar is in the food. This can be used to test for diabetes, by testing for sugar in the urine. More complex sugars such as starch can be tested for by using iodine, starch has a helix configuration with enough dimensions to accommodate the iodine molecules which in turn interact with the glucose molecules in the starch. When starch is present the the liquid will turn a blue-black colour indication the presence of starch. The test for proteins is known as the Biuret test, this uses a combination of sodium hydroxide and copper sulphate mixing them with the food will produce a colour change from blue, pink, lilac or violet depending on the concentration of proteins present. Lipids are characterised by their insoluble nature in water so to test for the presence of lipids a organic solvent called ethanol (meths) is used. When the unknown solution and ethanol is mixed together and diluted with a small amount of water. The presence of lipids will give a white cloudy like emulsion. To test for the presence of vitamin C a blue dye called DCPIP is used, the dye will lose its colour when in the presence of vitamin C (but not for other vitamins which are composed of different chemicals). There are many reasons why we need to know the presence of different substances in food, foods high in sugar may be a vital source of energy but not taken in proportion can lead to health problems such as obesity and diabetes, excess amounts of lipids in food can lead to high cholesterol which may cause heart problems, proteins are important in our diet as they act as a catalyst for the chemical reactions that occur in our bodies, vitamin C helps maintain strong bones and good eyesight. To know what is in our food helps to moderate what we eat providing us with all the nutrition we need for a healthy body.
Materials and methods
* Test tube rack
* Test tubes