Red cabbage juice provides an inexpensive, homemade way to make your own indicator liquid to test for acidity and alkalinity in food. Wear old clothes or cover up with a large apron as cabbage juice stains are difficult to remove. Place some cabbage leaves in a blender and fill it half-full with water. Puree the cabbage until the water turns purple and strain out the chunks, reserving the liquid for your experiment. Fill two clear glasses half-full of the cabbage juice. Add 1 teaspoon of vinegar to glass one and 1 teaspoon of laundry detergent to glass two. The first should turn red to indicate acid and the second green to indicate basic alkalinity. Prepare more clear glasses with cabbage juice and test other items, such as orange juice, lemonade, milk, salt, baking soda, lemon juice or soda pop. The more acidic a food is, the deeper red the liquid will be; the more basic or alkaline, the greener it will turn.
Knowing what is in your food helps you make healthier dietary choices. Simple tests can indicate the levels of various vitamins, minerals and nutrients. A cornstarch and iodine solution gives you an easy way to check for relative levels of vitamin C. Add a small amount of water to 1 tablespoon cornstarch to make a paste. Boil the paste in 1 cup water for five minutes. Put 10 drops of this starch solution into 1/3 cup of water. Add drops of 2 percent iodine solution (available at a pharmacy) until the liquid turns dark purple-blue. Mix 1 teaspoon of this indicator solution with 10 drops of fruit juice, milk, soda pop or juice pureed from solid foods in a clean test tube, beaker or glass labeled with its test food. The liquid will turn purple in reaction to the vitamin C content. Repeat with different food types and line up the test containers from lightest to darkest. Vitamin C drains the purple color from the solution, so the lighter the color, the higher the vitamin C content.
Calories are the unit of measurement used to determine how much energy you get from eating a food item. More calories equals more energy and weight gain if you do not compensate with sufficient exercise and activity, while fewer calories translates to losing weight. So understanding your caloric intake is important to helping you meet your dietary needs and weight goals. To test a food sample for calorie content, weigh a portion on a gram scale. Weigh a 1/3 cup measure in grams, fill it with water and measure it again. Subtract the cup weight to find the water weight. Pour the water into a clean tin can and measure the starting water temperature in degrees Celsius. Punch two opposite holes in the rim of the smaller can and slide a glass rod through the holes. Suspend the smaller can, letting the rod rest on the rim of the larger can so that the can hangs down into the larger one. Straighten a metal paper clip and insert one end into a cork. Skewer the food sample on the other end and set the cork on a safe, non-flammable surface. Put on safety glasses and set the food on fire. When it starts to burn, cover it with the coffee can. Let it burn one minute or more until consumed, relighting if necessary. Measure the water temperature again and weigh the food remnants. To calculate the caloric content of your food sample, multiply the starting gram weight of the water times one calorie per gram times the difference between the starting and ending water temperatures. This will tell you how much energy was lost by the food sample and transferred to the water as heat energy or calories.
Taste tests tell manufacturers about their customers' taste preferences to enable them to make decisions about those products that will improve their profit margin. Choose a food product that has several varieties or brands, such as apples, peanut butter or chocolate chip cookies. Set up a blind taste test and have the subjects rate each type on taste factors such as sweetness, tartness, crunchiness, consistency, moistness, chewiness, number of nuts or chocolate chips and size. Ask them to take all these factors into consideration and list the varieties in order of preference, from first choice or most favorite to last choice or least favorite. Analyze the preference indicators for any common trends in which taste factors most influence a consumer's purchasing decision. Write a paragraph recommending which type of product a company should develop to appeal to the greatest number of consumers.