In the science week at AIE, we had an opportunity to interact with school science teachers on a number of different workshops. Out of five workshops I enjoyed conducting the workshop entitled ‘Kitchen Chemistry’ the most. The aim of this workshop was to help teachers explore how to use everyday kitchen items to conduct science experiments. During the workshop participants identified major food groups and the additives they contain. They performed simple experiments using kitchen ingredients and identified different physical and chemical changes taking place during in the kitchen.
The topic was introduced by an activity in which I prepared tea and a sandwich in front of the class, discussing how these are made up of number of chemical compounds. Tea is a mixture of caffeine, water, sugar and milk. Bread is made from three main ingredients: water, grains and leavener (also called raising agent). Making bread from yeast is an aerobic reaction. Cooked bread has a spongy texture due to carbon dioxide. We also discussed that there are many food items that contain additives which are mainly artificial in the form of colouring agents, flavouring agents, emulsifiers, stabilizers, preservatives, gelling and glazing agents.
The groups made jelly and sandwiches with mayonnaise and boiled eggs. When eggs are cooked they become firmer. This is because cooking changes the shape of the amino acid chains in the egg. This is called ‘denaturing’. Mayonnaise is an emulsion. It does not separate when it is left to stand. Mayonnaise is made using egg yolk. This contains lecithin, which is a natural emulsifier. Jelly is formed due to pectin which is a carbohydrate found in fruits. When sugar is added, the pectin in fruit precipitates out and forms insoluble fibres. We also discussed different chemical compounds which are responsible for the colours of different vegetables - for instance: orange is ?- and ?-carotene; red is lycopene; purple is anthocyanins; yellow is flavonoids; yellow-green is lutein.
The workshop ended with lots of laughter - the participants learnt and had fun at the same time.