WEBVTT 00:00:00.000 --> 00:00:04.566 Experiment OB3A, To test a variety of foods for the pressence of startch. 00:00:04.696 --> 00:00:09.984 The Experiment involves the use of chemicals. So wear safety goggles and gloves during the experiment. 00:00:10.091 --> 00:00:17.251 Today the chemical we will be using is Iodine solution. Which is Redish / Brown colour. 00:00:17.251 --> 00:00:20.836 And it will stain blue / black when startch is present. 00:00:20.913 --> 00:00:24.689 The foods we will be testing are Potatoe, Flour and Milk. 00:00:24.736 --> 00:00:33.071 The experiment simply involves adding a few drops of Iodine. To each food sample. 00:00:33.086 --> 00:00:38.750 When a few drops are added to the potatoe. It will stain Blue / Black in colour. 00:00:38.750 --> 00:00:44.088 Which indicates startch is present. 00:00:44.088 --> 00:00:53.080 When we add the chemical to flour. Again it will stain Blue / Black. 00:00:53.080 --> 00:00:59.084 And when we finally add the solution to the milk, there is no colour change... 00:00:59.084 --> 00:01:02.537 Indicating that there is no startch present in milk. 00:01:02.537 --> 00:01:06.133 That concludes Experiment OB3A... 00:01:06.148 --> 00:01:12.694 Experiment OB3B. Test a variety of foods for the pressence of reducing sugars. 00:01:12.694 --> 00:01:15.827 As with all experiments involving he use of chemicals. 00:01:15.827 --> 00:01:18.844 Safety glasses and gloves must be worn. 00:01:18.844 --> 00:01:26.200 3 Food samples we are going to use today are: Milk, Glucose Solution and Water. Which is acting as our control. 00:01:26.200 --> 00:01:36.838 The chemical involved is "Benedict's Solution." And it is added in equal volumes to each food sample. 00:01:36.838 --> 00:01:40.647 The food samples are then heated in a water bath. 00:01:40.693 --> 00:01:46.186 So, I'm going to add Benedict's Solution to each of the testubes... 00:01:46.186 --> 00:01:55.618 You add an equal amount of Benedict's to the amount of liquid in the testube. 00:01:55.664 --> 00:02:06.588 The testubes then need to be given a brief shake. To ensure that the liquids are fully mixed... 00:02:12.218 --> 00:02:17.926 Experiment - OB3C. To test a food sample for the presence of fat. 00:02:18.022 --> 00:02:21.148 Once again, we will need out Safety goggles and gloves. 00:02:21.590 --> 00:02:26.309 This experiment involves: Rubbing the food sample on Brown paper. 00:02:26.401 --> 00:02:32.166 I'm using butter, today. So, place a sample of butter onto the brown paper. 00:02:32.166 --> 00:02:42.180 And then, Rub the food sample on the brown paper. And take off the butter afterwards... 00:02:42.180 --> 00:02:49.181 And what we are looking for is, the presence of this spot. Which is known as a "Translucent" spot. 00:02:49.781 --> 00:02:55.303 It's similar to a grease spot. And it allows light to pass through it, but you can't actually see through 00:02:55.303 --> 00:03:03.297 the spot. And once you get that spot on the brown paper. That indicates the sample HAS fat in it. 00:03:03.297 --> 00:03:07.677 If you don't get that spot. Then the food sample does not contain fat... 00:03:07.677 --> 00:03:12.440 And that is the end of experiment OB3C... 00:03:12.440 --> 00:03:18.515 Experiment - OB3D. To test a variety of foods for the presence of Protein. 00:03:18.515 --> 00:03:23.667 Again, Safety goggles and gloves must be worn when handling chemicals in the lab. 00:03:23.667 --> 00:03:29.251 Today, we will use 2 food samples. Water and Milk. The chemicals involved in this test... 00:03:29.251 --> 00:03:36.592 Are "Sodium Hydroxide" and "Copper Sulfate." 00:03:36.592 --> 00:03:41.816 The first stage involves adding Sodium Hydroxide to the food samples. And you must add aprox. an equal 00:03:41.816 --> 00:03:53.907 volume of sodium hydroxide to the food sample being tested. 00:03:53.907 --> 00:04:07.662 The testubes must be briefly shaken to ensure the chemicals are mixed. 00:04:07.662 --> 00:04:12.654 And the last stage of this experiment involves adding a few drops of copper sulfate. 00:04:12.654 --> 00:04:17.761 As you can see copper sulfate is a Blue chemical. And if there is protein present in the sample, It will 00:04:17.761 --> 00:04:25.493 stain purple, when it meets the sample. 00:04:25.493 --> 00:04:28.410 As you can see, there is no colour change in the testube containing the water. Which indicates there 00:04:28.410 --> 00:04:35.322 is an Protein is absent in water. When added to the Milk... 00:04:35.384 --> 00:04:50.529 We should get a purple colour appearing at the top of the solution. This indicates protein is present 00:04:50.544 --> 00:04:57.075 in Milk. That is the end of experiment OB3D... 00:04:57.075 --> 00:05:05.169 Experiment - OB5. To investigate the conversion of chemical energy in food into heat energy. 00:05:05.184 --> 00:05:10.154 Safety goggles and gloves must be worn during this experiment. 00:05:10.154 --> 00:05:18.148 We are going to use a cream cracker as our food source. And we are going to ignite the cream cracker... 00:05:18.148 --> 00:05:22.320 And the chemical energy in the cream cracker, will be converted into heat energy. And will cause the 00:05:22.320 --> 00:05:25.571 temperature of the water to rise... 00:05:25.571 --> 00:05:52.779 Initally, the Temperature of the water is 23 oC. We will ignite the cream cracker using the bunsen burner. 00:05:52.779 --> 00:05:59.884 As the cream cracker burns, it emits chemical energy in the form of heat energy. This energy is being 00:05:59.884 --> 00:06:08.949 trapped by the water, and will cause the rise in temperature. 00:06:08.949 --> 00:06:32.114 We will allow the cream cracker to completely burn itself out... 00:06:32.114 --> 00:06:39.151 If we examine the temperature of the water in the testube, we will see it has risen from 23 oC to.. 00:06:39.151 --> 00:06:50.654 50 oC. A rise of 27 oC. This shows the conversion of chemical energy in food into heat energy. 00:06:50.685 --> 00:06:56.596 Experiment - OB8. To investigate the action of the enzyme amylase on startch. 00:06:56.596 --> 00:07:01.763 Safety goggles and Gloves must be worn as chemicals are involved. 00:07:01.778 --> 00:07:07.496 Testube on the right contains startch and saliva. The one on the left contains startch and water. 00:07:07.496 --> 00:07:15.707 Saliva contains an enzyme called amylase. And that enzyme breaks down startch into a product called... 00:07:15.707 --> 00:07:31.532 Maltose. We will place the 2 testubes into a water bath at 37 oC for about 10 min. 00:07:31.532 --> 00:07:40.062 We now remove the 2 testubes from the water bath and test both testubes for the presence of startch... 00:07:40.108 --> 00:07:44.692 Using Iodine. 00:07:44.692 --> 00:07:53.701 We add a few drops of Iodine into each testube. 00:07:53.701 --> 00:08:02.410 The testube on the left, Iodine stays yellow / brown in colour. Indicating no startch present. 00:08:02.410 --> 00:08:09.160 The testube on the right stains blue / back. Indicating the presence of startch. 00:08:09.160 --> 00:08:17.898 From this experiment we can conclude that the amylase broke startch down into maltose. 00:08:17.898 --> 00:08:24.159 Where as the other testube, which was acting as a control. The iodine stained blue / back... 00:08:24.175 --> 99:59:59.999 indicating the presence of startch. That is the end of experiment OB8...