Food Science and Nutrition Demonstrations

See also: Kitchen Chemistry

Food science demonstrations use everyday ingredients to reveal the chemistry and biology of what we eat. They are engaging because they connect science directly to daily life in a familiar and hands-on way.

Demonstration	Materials	Difficulty	Safety	Summary
Action of Salivary Amylase on Starch	★★☆	★★☆	★★☆	This demonstration shows how salivary amylase breaks down starch in cooked rice into simpler sugars like maltose. Students use chemical tests to identify starch and reducing sugars while learning about enzyme activity and its dependence on conditions such as temperature.
Biuret Test for Protein	★★☆	★☆☆	★☆☆	The Biuret test detects proteins in food samples. When a protein such as egg white or milk is mixed with Biuret solution, the color changes from blue to violet. If no protein is present, the solution remains blue.
Cooking an Egg Without Heat	★★☆	★☆☆	★★☆	This experiment shows how alcohol can denature proteins in egg whites, causing them to coagulate and turn white, just like when cooking with heat. It demonstrates protein structure disruption and how proteins lose their natural shape under different conditions.
Cracking an Egg Underwater	★☆☆	★★★	★★★	When a raw egg is cracked open underwater at depth, the water pressure holds the egg white and yolk together in a jelly-like sphere. It resembles a floating sea creature and demonstrates how pressure and buoyancy act on fluids without a shell.
Dry Ice Carbonated Ice Cream	★★★	★★☆	★★☆	By mixing a simple ice cream base with dry ice, the mixture freezes rapidly while also becoming lightly carbonated.
Energy in Food	★★☆	★★☆	★★☆	A small piece of dry food is burned beneath a boiling tube containing water, and the rise in water temperature is measured. From this, the approximate energy released is calculated.
Floating Egg	★☆☆	★☆☆	★☆☆	This experiment demonstrates how adding salt to water changes its density. A raw egg sinks in plain water but floats in saltwater because the denser solution supports the egg.
Food Test for Fats and Oils	★★☆	★☆☆	★☆☆	The emulsion test detects fats and oils in food. The sample is first dissolved in ethanol, then mixed with water. A milky-white emulsion indicates the presence of lipids, while a clear solution means none are present.
Liquid Nitrogen Freezing Marshmallows	★★★	★★☆	★★★	Marshmallows frozen in liquid nitrogen become crisp and brittle. When eaten, the extreme cold condenses the water vapor in exhaled breath, creating a dramatic “dragon’s breath” fog effect.
Liquid Nitrogen Ice Cream	★★★	★★☆	★★★	creamy ice cream is made by rapidly freezing a prepared base with liquid nitrogen, creating very small ice crystals that give it a smooth texture.
Making Casein Plastic	★☆☆	★☆☆	★☆☆	Heating milk and mixing it with vinegar causes the protein casein to separate and form curds. These curds can be dried and kneaded into a moldable bioplastic that hardens over time, demonstrating polymer formation.
Making Poo: Modeling the Digestive System	★☆☆	★☆☆	★☆☆	Students create a hands-on model of the digestive system using everyday materials to show how food is broken down, nutrients are absorbed, and waste is excreted as poo. This activity helps students visualize and understand the stages of digestion and the role of each organ.
Making Yogurt	★☆☆	★★☆	★★☆	Students heat and cool milk, add a starter containing live bacterial cultures, and allow the mixture to incubate in a warm environment. Over several hours, the bacteria ferment lactose into lactic acid, thickening the milk and producing yogurt.
Microwave Hot Spots With Marshmallows	★★☆	★☆☆	★★☆	Marshmallows are heated in a microwave with and without the rotating tray to reveal the uneven distribution of energy inside the oven. This demonstrates how microwaves create hot and cold spots due to their wave pattern.
Naked Egg (Bouncy Egg)	★☆☆	★☆☆	★☆☆	When an egg is placed in vinegar, the acid reacts with the calcium carbonate of the eggshell, producing carbon dioxide bubbles and dissolving the shell. What remains is a soft, rubbery membrane that can stretch and even bounce.
Observing Yogurt Bacteria	★★☆	★☆☆	★★☆	Students prepare microscope slides of live yogurt cultures to observe probiotic bacteria such as Lactobacillus and Streptococcus.
Pineapple Enzymes and Geletin	★☆☆	★☆☆	★☆☆	Bromelain in fresh pineapple prevents jelly from setting by digesting the gelatine protein.
Potato Catalase Hydrogen Peroxide Decomposition	★★☆	★☆☆	★☆☆	Students observe how the enzyme catalase in potato accelerates the decomposition of hydrogen peroxide into water and oxygen. By comparing room-temperature, boiled, and frozen potato, they explore how temperature affects enzyme activity.
PTC Genetic Taste Test	★★★	★☆☆	★☆☆	The ability to taste phenylthiocarbamide (PTC) is controlled by a single gene, TAS2R38, which codes for a bitter taste receptor. Variants of this gene determine whether individuals find PTC intensely bitter, slightly bitter, or tasteless. This simple Mendelian trait illustrates genetic variation, natural selection, and sensory perception.
Rock Candy	★★☆	★★☆	★★☆	Dissolve sugar into hot water until it forms a supersaturated solution, then suspend sugar-coated sticks in jars to grow edible sugar crystals over several days. Color or flavor can be added to make decorative, tasty rock candy.
Sinking and Floating Soda Cans	★☆☆	★☆☆	★☆☆	This demonstration compares the buoyancy of regular and diet soda cans. Regular soda sinks in water because dissolved sugar makes it slightly denser than water, while diet soda floats because it uses a much smaller mass of artificial sweetener. Adding salt to the water increases its density so that even the regular soda can floats.
Sweet Cracker	★☆☆	★☆☆	★☆☆	The enzyme amylase in saliva breaks down starch into sugar. A cracker initially tastes bland, but the longer it is chewed, the sweeter it becomes as starch is converted to glucose.
Testing Foods for Reducing Sugars	★★☆	★☆☆	★☆☆	Benedict’s solution is used to test foods for the presence of reducing sugars such as glucose. When heated with a reducing sugar, the blue solution changes to green, yellow, orange, or brick red depending on the sugar concentration.
Testing for Starch in Food	★★☆	★☆☆	★★☆	This activity uses iodine as an indicator to test different foods for starch. When iodine comes in contact with starch, it produces a dark blue or purple-black color, while foods without starch remain brownish-yellow.

Materials
★☆☆ Easy to get from supermarket or hardware store
★★☆ Available in most school laboratories or specialist stores
★★★ Requires materials not commonly found in school laboratories

Difficulty
★☆☆ Can be easily done by most teenagers
★★☆ Available in most school laboratories or specialist stores
★★★ Requires a more experienced teacher

Safety
★☆☆ Minimal safety procedures required
★★☆ Some safety precautions required to perform safely
★★★ Only to be attempted with adequate safety procedures and trained staff