0:00:00.000,0:00:04.566 Experiment OB3A, To test a variety of foods for the pressence of startch. 0:00:04.696,0:00:09.984 The Experiment involves the use of chemicals. So wear safety goggles and gloves during the experiment. 0:00:10.091,0:00:17.251 Today the chemical we will be using is Iodine solution. Which is Redish / Brown colour. 0:00:17.251,0:00:20.836 And it will stain blue / black when startch is present. 0:00:20.913,0:00:24.689 The foods we will be testing are Potatoe, Flour and Milk. 0:00:24.736,0:00:33.071 The experiment simply involves adding a few drops of Iodine. To each food sample. 0:00:33.086,0:00:38.750 When a few drops are added to the potatoe. It will stain Blue / Black in colour. 0:00:38.750,0:00:44.088 Which indicates startch is present. 0:00:44.088,0:00:53.080 When we add the chemical to flour. Again it will stain Blue / Black. 0:00:53.080,0:00:59.084 And when we finally add the solution to the milk, there is no colour change... 0:00:59.084,0:01:02.537 Indicating that there is no startch present in milk. 0:01:02.537,0:01:06.133 That concludes Experiment OB3A... 0:01:06.148,0:01:12.694 Experiment OB3B. Test a variety of foods for the pressence of reducing sugars. 0:01:12.694,0:01:15.827 As with all experiments involving he use of chemicals. 0:01:15.827,0:01:18.844 Safety glasses and gloves must be worn. 0:01:18.844,0:01:26.200 3 Food samples we are going to use today are: Milk, Glucose Solution and Water. Which is acting as our control. 0:01:26.200,0:01:36.838 The chemical involved is "Benedict's Solution." And it is added in equal volumes to each food sample. 0:01:36.838,0:01:40.647 The food samples are then heated in a water bath. 0:01:40.693,0:01:46.186 So, I'm going to add Benedict's Solution to each of the testubes... 0:01:46.186,0:01:55.618 You add an equal amount of Benedict's to the amount of liquid in the testube. 0:01:55.664,0:02:06.588 The testubes then need to be given a brief shake. To ensure that the liquids are fully mixed... 0:02:12.218,0:02:17.926 Experiment - OB3C. To test a food sample for the presence of fat. 0:02:18.022,0:02:21.148 Once again, we will need out Safety goggles and gloves. 0:02:21.590,0:02:26.309 This experiment involves: Rubbing the food sample on Brown paper. 0:02:26.401,0:02:32.166 I'm using butter, today. So, place a sample of butter onto the brown paper. 0:02:32.166,0:02:42.180 And then, Rub the food sample on the brown paper. And take off the butter afterwards... 0:02:42.180,0:02:49.181 And what we are looking for is, the presence of this spot. Which is known as a "Translucent" spot. 0:02:49.781,0:02:55.303 It's similar to a grease spot. And it allows light to pass through it, but you can't actually see through 0:02:55.303,0:03:03.297 the spot. And once you get that spot on the brown paper. That indicates the sample HAS fat in it. 0:03:03.297,0:03:07.677 If you don't get that spot. Then the food sample does not contain fat... 0:03:07.677,0:03:12.440 And that is the end of experiment OB3C... 0:03:12.440,0:03:18.515 Experiment - OB3D. To test a variety of foods for the presence of Protein. 0:03:18.515,0:03:23.667 Again, Safety goggles and gloves must be worn when handling chemicals in the lab. 0:03:23.667,0:03:29.251 Today, we will use 2 food samples. Water and Milk. The chemicals involved in this test... 0:03:29.251,0:03:36.592 Are "Sodium Hydroxide" and "Copper Sulfate." 0:03:36.592,0:03:41.816 The first stage involves adding Sodium Hydroxide to the food samples. And you must add aprox. an equal 0:03:41.816,0:03:53.907 volume of sodium hydroxide to the food sample being tested. 0:03:53.907,0:04:07.662 The testubes must be briefly shaken to ensure the chemicals are mixed. 0:04:07.662,0:04:12.654 And the last stage of this experiment involves adding a few drops of copper sulfate. 0:04:12.654,0:04:17.761 As you can see copper sulfate is a Blue chemical. And if there is protein present in the sample, It will 0:04:17.761,0:04:25.493 stain purple, when it meets the sample. 0:04:25.493,0:04:28.410 As you can see, there is no colour change in the testube containing the water. Which indicates there 0:04:28.410,0:04:35.322 is an Protein is absent in water. When added to the Milk... 0:04:35.384,0:04:50.529 We should get a purple colour appearing at the top of the solution. This indicates protein is present 0:04:50.544,0:04:57.075 in Milk. That is the end of experiment OB3D... 0:04:57.075,0:05:05.169 Experiment - OB5. To investigate the conversion of chemical energy in food into heat energy. 0:05:05.184,0:05:10.154 Safety goggles and gloves must be worn during this experiment. 0:05:10.154,0:05:18.148 We are going to use a cream cracker as our food source. And we are going to ignite the cream cracker... 0:05:18.148,0:05:22.320 And the chemical energy in the cream cracker, will be converted into heat energy. And will cause the 0:05:22.320,0:05:25.571 temperature of the water to rise... 0:05:25.571,0:05:52.779 Initally, the Temperature of the water is 23 oC. We will ignite the cream cracker using the bunsen burner. 0:05:52.779,0:05:59.884 As the cream cracker burns, it emits chemical energy in the form of heat energy. This energy is being 0:05:59.884,0:06:08.949 trapped by the water, and will cause the rise in temperature. 0:06:08.949,0:06:32.114 We will allow the cream cracker to completely burn itself out... 0:06:32.114,0:06:39.151 If we examine the temperature of the water in the testube, we will see it has risen from 23 oC to.. 0:06:39.151,0:06:50.654 50 oC. A rise of 27 oC. This shows the conversion of chemical energy in food into heat energy. 0:06:50.685,0:06:56.596 Experiment - OB8. To investigate the action of the enzyme amylase on startch. 0:06:56.596,0:07:01.763 Safety goggles and Gloves must be worn as chemicals are involved. 0:07:01.778,0:07:07.496 Testube on the right contains startch and saliva. The one on the left contains startch and water. 0:07:07.496,0:07:15.707 Saliva contains an enzyme called amylase. And that enzyme breaks down startch into a product called... 0:07:15.707,0:07:31.532 Maltose. We will place the 2 testubes into a water bath at 37 oC for about 10 min. 0:07:31.532,0:07:40.062 We now remove the 2 testubes from the water bath and test both testubes for the presence of startch... 0:07:40.108,0:07:44.692 Using Iodine. 0:07:44.692,0:07:53.701 We add a few drops of Iodine into each testube. 0:07:53.701,0:08:02.410 The testube on the left, Iodine stays yellow / brown in colour. Indicating no startch present. 0:08:02.410,0:08:09.160 The testube on the right stains blue / back. Indicating the presence of startch. 0:08:09.160,0:08:17.898 From this experiment we can conclude that the amylase broke startch down into maltose. 0:08:17.898,0:08:24.159 Where as the other testube, which was acting as a control. The iodine stained blue / back... 0:08:24.175,9:59:59.000 indicating the presence of startch. That is the end of experiment OB8...