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Investigate and compare the amount of proteins, lipids and carbohydrates in three different types of milk; soy milk, skim (or fat free) milk and fresh milk.

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Bertha Z��iga Group 4 Project: Biology Planning A Aim: To investigate and compare the amount of proteins, lipids and carbohydrates in three different types of milk; soy milk, skim (or fat free) milk and fresh milk. Hypothesis: * Skim milk will have less fat compared to fresh milk. * Soy milk will have more proteins than skim and fresh milk. * Fresh milk will have a balanced amount of proteins, carbohydrates and lipids. Variables that will be kept constant: * Volume of samples * Quantity of milk Independent variables: * Types of milk * Impurities in milk Dependant variables: * Temperature Notes: * Skim milk and whole milk come from animals. * Soy milk comes from plants. Planning B: Materials * 15 grams of soy milk (powder form) mixed with 500ml of water * Skim milk (fat free) * Fresh milk * Benedict's solution * Sodium hydroxide * Copper sulphate * Alcohol * Distilled water * Liver * Piece of fat * Test tubes * Filter paper * Glucose * Funnel * Beakers * Glass rod * Dropper * Clamp stand * Bunsen burner * Tripod * Heat proof mat * Gauze * Matches * Mortar * Pestle Methods: In order to accomplish our aim, testing for proteins, carbohydrates and lipids had to be done: Testing for proteins: 1. Pour 1.3 cm3 of fresh milk in a test tube. ...read more.


Mix 5 cm3 of liver and 15 cm3 of water 2. Filtrate the solution 3. Put 1.3 cm3 of the solution obtained in a test tube 4. Add five drops of sodium hydroxide. 5. Add five drops Copper Sulphate. 6. Observe and record the colour change (if any). This colour revels the presence of proteins. For the Carbohydrates (reducing sugars) test, glucose was used because glucose is the most common monosaccharide: 1. Make a mixture of 2 cm3 of glucose and 2 cm3 of water. 2. Pour the mixture into a test tube and add 2 cm3 Benedict's solution. 3. Place it in hot water. 4. Observe and record the colour change (if any). This colour reveals the presence of reducing sugars. For the Lipids test oil was used because oil is a lipids. 1. Add 1.3 cm3 of alcohol to 1.3 cm3 of oil. 2. Filtrate the solution. 3. Pour filtrated solution into 1.3 cm3 of water. 4. Observe and record any change in the water. This change reveals the presence of lipids. Data collection: Test for Carbohydrates Table showing the color change for the types of milk and the control Types of milk and control Control (glucose) Fresh milk Soy milk Skim milk Color change Bright orange Yellow orange Bright orange Yellow orange Time for the change 30 seconds 1:07 2:00 1:30 Most amount of carbohydrates (one for the least amount and three for the largest amount) ...read more.


This test was done three times to get acurrent results, even more testing will give more acurrent results. For the testing of lipids, first, a piece of animal fat was used as the sample, but as it could not be proof to be pure fat, oil was used instead. Also, when the milk was separated into fat and water, the quantity used was small, so it made it hard to see the thin layer of fat formed. Therefore, this think layer was absorbed by means of a dropper. More quantity of every substance should have been used for clearer results. Also, it was complicated to have acurrent results, as it is difficult to measure the cloudiness of the solution. In further experiments milk temperature has to be controlled as it was different (this is because for example fresh milk had to be kept refrigerated to avoid souring). The temperature of the milk might have varied, we did not control this variable at all and this might have affected the result of the experiment. We could have taken the temperatures of the milks or even heat them so that they were all at the same warmth. This way the results could be more precise helping us reach a consistent conclusion It should be considered that the fresh milk used had been actually pasteurized and therefore the bacteria in it was killed through the UHT test (ultra height temperature, where milk has been held at 132�C for 2 seconds) On the other hand, fresh milk, straight from a healthy cow contains few bacteria. ...read more.

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