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food groups present in chemcial testina

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An experiment to discover the types of food groups present in food using chemical testing. Introduction Carbohydrates are organic molecules that contain 3 elements carbon, hydrogen and oxygen. The two types of carbohydrates that are being investigated in this experiment are sugars and starches. There are three basic types of carbohydrate molecules that are form its structure, these are: * Monosaccharides - which are single sugars. * Disaccharides - double sugars made from two monosaccarides. * Polysaccharides - multiple sugars (polymers of many monosaccarides). Carbohydrates have several functions and roles within the human body, for example, starches are ideal for storage and sugar is ideal for energy. As well as being vital in structural components, a good example is connective tissue, chitin in crabs and cellulose. Lipids or more commonly known as waxes, fats and oils are non - polar molecules. Most are insoluble in water but are soluble in non - polar solvents such as alcohol. Lipids contain several elements, carbon, hydrogen, oxygen and sometimes nitrogen and phosphorus. When testing for lipids - food should be cut up into small pieces and mixed with pure ethanol, which is then shaken. If lipids were present they would dissolve in the alcohol. By removing some of the solution and mixing it with water, a portion of the solution would turn white, with a small amount of lipid droplets forming on top of the solution. ...read more.


* Quaternary structure - Each protein consists of several polypeptide chains, which are bonded together to form intricate shapes. For example, a haemoglobin molecule is form from four separate polypeptide chains. Hypothesis It is to be expected that it will be possible to use chemical testing to discover what food group is present in different food products. Safety Assessment Tying hair back Can catch alight with the Bunsen flame, and gets in the way of working. Goggles Must be worn, as liquids are being used. They protect the eyes from any splashes. Liquids Ensure that all liquids are identified and hazardous chemicals have correct labels on. Lab coats Worn to protect clothes Bags and stools Keep them both tucked under tables or moved out of the way for a clear fire exit, and to prevent falling over them, etc. Spillages and breakages Ensure that all spillages and breakages are reported, in order for them to be taken care of correctly and safely. Method Each food product being tested needs to be pureed using a pestle and mortar, adding water to form a runny puree. When testing for sugars (carbohydrates) 1. The hot plates were turned on, with a beaker of boiling water placed on top, which was left to boil. 2. Using a syringe, 2mls of the puree food was added to a test tube. ...read more.


Most man made food products tend to contain lots of things that give it some form of 'nutritional value', despite the fact it's not natural. Starch is commonly found in most plants, and for it not to show up when testing almonds, may be due to error when testing. The rest of the results were expected due to previous knowledge on both food product and food group. Evaluation When testing for lipids (the emulsion test), it was difficult to see if there were any un-dissolved fat/oil lying on top of the food and water mixture. If the experiment were to be carried out again, instead I would use filter paper, as a positive result would turn part of the filter paper clear/translucent. Another test is using Sudan III, which will stain fat cells red if present. (www.sciencecompany.com) When testing for proteins with almonds, it originally didn't turn purple. It wasn't until when clearing away that a slight colour change was observed. For future testing, all test tubes should be left for the same length of time, to see if any take longer to produce a positive or negative result. With this each test should be repeated twice to prevent any error. I would also carry out further testing on other food groups, for example using Vitamin C Reagent (dichlorophenolindophenol). This is a blue indicator solution and will turn colourless when an end point is reached with a solution containing vitamin C. (www.sciencecompany.com) Reference Science Company: http://www.sciencecompany.com/sci-exper/food_chemistry.htm (viewed: 24/02/2009) Boyle, M., Senior, K., (Ed) (2002) Human biology. London: Harper Collins Publishers Class notes and worksheets ...read more.

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