1 00:00:00,000 --> 00:00:04,566 Experiment OB3A, To test a variety of foods for the pressence of startch. 2 00:00:04,696 --> 00:00:09,984 The Experiment involves the use of chemicals. So wear safety goggles and gloves during the experiment. 3 00:00:10,091 --> 00:00:17,251 Today the chemical we will be using is Iodine solution. Which is Redish / Brown colour. 4 00:00:17,251 --> 00:00:20,836 And it will stain blue / black when startch is present. 5 00:00:20,913 --> 00:00:24,689 The foods we will be testing are Potatoe, Flour and Milk. 6 00:00:24,736 --> 00:00:33,071 The experiment simply involves adding a few drops of Iodine. To each food sample. 7 00:00:33,086 --> 00:00:38,750 When a few drops are added to the potatoe. It will stain Blue / Black in colour. 8 00:00:38,750 --> 00:00:44,088 Which indicates startch is present. 9 00:00:44,088 --> 00:00:53,080 When we add the chemical to flour. Again it will stain Blue / Black. 10 00:00:53,080 --> 00:00:59,084 And when we finally add the solution to the milk, there is no colour change... 11 00:00:59,084 --> 00:01:02,537 Indicating that there is no startch present in milk. 12 00:01:02,537 --> 00:01:06,133 That concludes Experiment OB3A... 13 00:01:06,148 --> 00:01:12,694 Experiment OB3B. Test a variety of foods for the pressence of reducing sugars. 14 00:01:12,694 --> 00:01:15,827 As with all experiments involving he use of chemicals. 15 00:01:15,827 --> 00:01:18,844 Safety glasses and gloves must be worn. 16 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. 17 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. 18 00:01:36,838 --> 00:01:40,647 The food samples are then heated in a water bath. 19 00:01:40,693 --> 00:01:46,186 So, I'm going to add Benedict's Solution to each of the testubes... 20 00:01:46,186 --> 00:01:55,618 You add an equal amount of Benedict's to the amount of liquid in the testube. 21 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... 22 00:02:12,218 --> 00:02:17,926 Experiment - OB3C. To test a food sample for the presence of fat. 23 00:02:18,022 --> 00:02:21,148 Once again, we will need out Safety goggles and gloves. 24 00:02:21,590 --> 00:02:26,309 This experiment involves: Rubbing the food sample on Brown paper. 25 00:02:26,401 --> 00:02:32,166 I'm using butter, today. So, place a sample of butter onto the brown paper. 26 00:02:32,166 --> 00:02:42,180 And then, Rub the food sample on the brown paper. And take off the butter afterwards... 27 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. 28 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 29 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. 30 00:03:03,297 --> 00:03:07,677 If you don't get that spot. Then the food sample does not contain fat... 31 00:03:07,677 --> 00:03:12,440 And that is the end of experiment OB3C... 32 00:03:12,440 --> 00:03:18,515 Experiment - OB3D. To test a variety of foods for the presence of Protein. 33 00:03:18,515 --> 00:03:23,667 Again, Safety goggles and gloves must be worn when handling chemicals in the lab. 34 00:03:23,667 --> 00:03:29,251 Today, we will use 2 food samples. Water and Milk. The chemicals involved in this test... 35 00:03:29,251 --> 00:03:36,592 Are "Sodium Hydroxide" and "Copper Sulfate." 36 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 37 00:03:41,816 --> 00:03:53,907 volume of sodium hydroxide to the food sample being tested. 38 00:03:53,907 --> 00:04:07,662 The testubes must be briefly shaken to ensure the chemicals are mixed. 39 00:04:07,662 --> 00:04:12,654 And the last stage of this experiment involves adding a few drops of copper sulfate. 40 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 41 00:04:17,761 --> 00:04:25,493 stain purple, when it meets the sample. 42 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 43 00:04:28,410 --> 00:04:35,322 is an Protein is absent in water. When added to the Milk... 44 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 45 00:04:50,544 --> 00:04:57,075 in Milk. That is the end of experiment OB3D... 46 00:04:57,075 --> 00:05:05,169 Experiment - OB5. To investigate the conversion of chemical energy in food into heat energy. 47 00:05:05,184 --> 00:05:10,154 Safety goggles and gloves must be worn during this experiment. 48 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... 49 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 50 00:05:22,320 --> 00:05:25,571 temperature of the water to rise... 51 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. 52 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 53 00:05:59,884 --> 00:06:08,949 trapped by the water, and will cause the rise in temperature. 54 00:06:08,949 --> 00:06:32,114 We will allow the cream cracker to completely burn itself out... 55 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.. 56 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. 57 00:06:50,685 --> 00:06:56,596 Experiment - OB8. To investigate the action of the enzyme amylase on startch. 58 00:06:56,596 --> 00:07:01,763 Safety goggles and Gloves must be worn as chemicals are involved. 59 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. 60 00:07:07,496 --> 00:07:15,707 Saliva contains an enzyme called amylase. And that enzyme breaks down startch into a product called... 61 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. 62 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... 63 00:07:40,108 --> 00:07:44,692 Using Iodine. 64 00:07:44,692 --> 00:07:53,701 We add a few drops of Iodine into each testube. 65 00:07:53,701 --> 00:08:02,410 The testube on the left, Iodine stays yellow / brown in colour. Indicating no startch present. 66 00:08:02,410 --> 00:08:09,160 The testube on the right stains blue / back. Indicating the presence of startch. 67 00:08:09,160 --> 00:08:17,898 From this experiment we can conclude that the amylase broke startch down into maltose. 68 00:08:17,898 --> 00:08:24,159 Where as the other testube, which was acting as a control. The iodine stained blue / back... 69 00:08:24,175 --> 99:59:59,999 indicating the presence of startch. That is the end of experiment OB8...