Food chemistry makes an interesting project for a science fair. Try duplicating the experiments done by biochemist, Shirley Corriher, the author of CookWise: The Hows and Whys of Successful Cooking, which shows how scientific insights can be applied to traditional cooking. Here are two easy projects to try.
A Science Project on Food Acidity and Alkalinity
Cooking creates a variety of chemical reactions. In one of Ms. Corriher’s experiments on food acidity and alkalinity, she demonstrates how when red cabbage is added to a hot pan it turns blue. Red cabbage has anthocyanins, which are water soluble pigments that may appear red, purple or blue according to their ph level. pH is a measure of the acidity or basicity of a solution. The heat breaks down the cabbage’s red anthocyanine pigment, changing it from an acid to alkaline, and causing the color to change to blue.
When vinegar (an acid) is added to the hot cabbage it raises the acid level, and the cabbage turns red again. When baking soda (an alkaline) is then added, it neutralizes the acid and the cabbage turns blue again. Other foods with anthocyanins include black raspberries, red raspberries, blackberries, cherries, and the peel of eggplant.
To perform this experiment at a science fair, all that is needed is an electric frying pan, red cabbage, baking soda and vinegar.
A Science Project on Fruit and Vegetable Ripening
Another one of Shirley Corriher’s experiments involves how to speed up and slow down food ripening. Certain fruits and vegetables naturally produce ethylene gas, a gas which speeds up the ripening process.
Ethylene producing foods include apples, avocados, bananas (ripe), cantaloupe, kiwi, mangoes, melons, nectarines, papaya, peaches, pears, plums, and tomatoes, while ethylene-sensitive foods include bananas (unripe), broccoli, brussel sprouts, cabbage, carrots, cauliflower, cucumbers, eggplant, green beans, leafy greens, lettuce, peas, peppers, spinach, squash, sweet potatoes, and watermelon.
For the project, conduct various experiments placing an ethylene producing food with an unripe ethylene sensitive food in the same paper bag overnight and see the effects on the unripened fruit. For example, take a unripened avocado, which should be very green and hard, and put in either in a paper bag overnight with an apple. Compare the state of the avocado the next day to another unripened avocado that was not in the bag. The ripened avocado should be black and soft, a process that would normally take several days. It can also be compared to when two ethylene sensitive fruits are put together in a paper bag, as there should be no change to either fruit. An ethylene producing fruit alone with itself in a paper bag will also ripen faster, because the gas is contained.
For the project, needed items include a variety of ethylene producing and ethylene sensitive foods, paper or plastic bags, and before photos.
The testing of food acidity, alkalinity and gas production makes for a simple but interesting science fair project that any child could manage.