Food Tests Learning Objectives: To understand the main components of the human diet. To test for the presence of starch, glucose protein and fat in a food sample. Starter: List the 7 parts of the human diet.

Carbohydrates Water Protein Vitamins Minerals Fibre Fats

8A What’s in food? We can test foods to find out what chemicals they contain. Orangey-brown iodine turns blue-black when it reacts with starch. drop iodine solution onto the food black = starch

8A What’s in food? Blue Benedict’s solution turns orangey-red when it is boiled with glucose. blue turns orange/red = glucose heat chopped up food hot water

8A What’s in food? In the Biuret test the solution turns purple. chopped up food potassium hydroxide shake copper sulphate purple = protein

8A What’s in food? Fats go cloudy white when they are mixed with ethanol and water. Now see if you can use these tests to identify the food chemicals on the next slides. grind food with ethanol add water filter cloudy = fat

8A What’s in food? For each food, decide on the chemicals found in them. FatsProteinStarchGlucose Food sampleTestResult Iodine solutionorangey-brown Benedict’s testblue Biuret testpurple Ethanol testcloudy white

8A What’s in food? For each food, decide on the chemicals found in them. FatsProteinStarchGlucose Food sampleTestResult Iodine solutionblue-black Benedict’s testblue Biuret testblue Ethanol testclear

8A What’s in food? For each food, decide on the chemicals found in them. FatsProteinStarchGlucose Food sampleTestResult Iodine solutionorangey-brown Benedict’s testorangey-red Biuret testblue Ethanol testclear

8A What’s in food? For each food, decide on the chemicals found in them. FatsProteinStarchGlucose Food sampleTestResult Iodine solutionorangey-brown Benedict’s testorangey-red Biuret testblue Ethanol testclear

Practical Activity Safety First: Wear safety goggles Stand up Tuck your chair & bags under your desk Tie back long hair

Experiment! You’ve been given a sample of foods. Test these foods using the four food tests to see what energy chemicals they contain! Complete this table with your results. FoodStarchGlucoseProteinFat Cream Cake ????

1. A balanced diet… a) contains the same amounts of the main food groups b) contains healthy amounts of the main food groups c) doesn’t fall off the table. 2. A balanced diet for most people has more… a) fat than water b) carbohydrate than protein c) crisps than fruit. 8A A food test for YOU!

3. To test for protein in food you… a) add iodine solution b) do the Biuret test c) poke it with a big stick. 4. Sugar and starch are both… a) proteins b) fats c) carbohydrates. 8A A food test for YOU!

5. Iodine solutions turns blue-black with… a) starch b) protein c) age. 6. A food went orangey-red when it was boiled with Benedicts solution. It could be… a) a carrot b) a boiled sweet c) a sausage. 8A A food test for YOU!

Food Tests Learning Objectives: To understand the main components of the human diet. To test for the presence of starch, glucose protein and fat in a food sample.