Food Science By Penny and Shannon

Chemical Reactions How do we taste food? Once food enters the mouth, its chemical components find their way to the taste buds. Some taste buds react most to the presence of sodium ions, and you will taste "salt." Others react mostly to sugars, acids, alkaloids or glutamates in the food resulting in tasting "sweet," "sour," "bitter," or "umami." Our tongues have four basic types of taste buds: bitter, sour, salty, and sweet and our taste buds are located in specific areas on our tongues. Sour and bitter tastes can indicate food that is bad, under-ripe or even poisonous. Sweet, salty and savoury tastes indicate "good" foods. A sweet taste indicates foods that can give us energy—infants crave sweet foods, and lactose in milk is sweet. A salty taste indicates foods that can help us replace electrolytes lost through sweat or urination, and savoury tastes can lead us to foods containing amino acids that the body needs. Producing carbon dioxide (gas)

Safety Not meant to taste science experiments but today we are. Make sure equipment is clean as you will be tasting (hygienic practices: e.g.. Do not lick your fingers and place back into container. Read instructions carefully Cooking is all about chemical reactions so lets do an experiment that produces carbon dioxide (gas)

Making (eating) Sherbet Equipment (in pairs) Mixing container Measuring spoons Citric acid Bi-carb soda Icing sugar Instructions 1 & half teaspoons of citric acid Half teaspoon of bicarb soda 1 tablespoon of icing sugar Place all ingredients into the jar, put the lid on and shake until mixed well. Then put a pinch of sherbet on your tongue

Questions Describe what it tastes like Describe what it feels like What do you think makes it feel this way This is because when you lick sherbet, the citric acid dissolves in your saliva and reacts with the bi-carb soda. This chemical reaction produces carbon dioxide. Carbon dioxide is the gas and this tickles your tongue so sherbet tastes fizzy. You can make your tongue really tingle by pouring some sherbet into the palm of your hand and licking it up

Follow up activities Write a poem about the taste of sherbet Make some foods which rely on bubbles to taste good, e.g. honeycomb, boiled fruit cake, marshmallows and rice bubble snacks. Make a miniature fore extinguisher using a large screw top jar with a hole punched in the top. Dissolve 2 tablespoons of baking soda in a small amount of water in a jar. Add a smaller container of vinegar (don’t mix). Screw the lid on tightly making sure that the water mixture and the vinegar don’t mix. Screw on the lid tightly, tilt the jar and shake gently. The chemical reaction between the vinegar and soda produces carbon dioxide. This gas will force the solution out of the jar. A carbon dioxide fire extinguisher works on this basic principle too!

References Picture of Food http://www.jfaw.com/nutrition.html/ Picture of test tubes http://www.ehow.com/list_7162696_food-science- activities-kids.html/ Picture of tongue http://www.funegreets.com/birthday/bday7.htm/ CSIRO Science Education Centre. (2011, March 10). Retrieved April 1, 2011, from http://www.csiro.au/resources/Teachers.html/