Ants on a Log Pennsylvania Academic Standards for Science and Technology: 3.1.4.E Long ago, people would go hungry when they ran out of fresh food. Today, we have the ability to keep food fresh for a long time and we can eat what we want throughout the year. How can we keep food fresh for so long? Through PRESERVATION, the molds, bacteria and enzymes that make food spoil have been destroyed or slowed down. The process of preservation changes the color, texture, taste or nutritional value of food. There are many ways to preserve food: drying, salting, smoking, pickling, canning, refrigerating and freezing. You probably already know that raisins are dried grapes. But, do you know HOW and WHY the drying process works? You will need: A bunch of green seedless grapes 1 drying tray (spread cheese cloth over kitchen drying rack) A pot of boiling water A strainer What to do: Wash the grapes in cold water and remove those that are bruised. Pull out the stems and place the cleaned grapes in the strainer. Dip them into a pot of boiling water so that the skins break. Spread the grapes on the drying tray so that they don't touch. There are two methods that you can use. For 4 or 5 days, place the trays by a sunny window, turning them every hour so that the fruit dries evenly. Or place the trays on the middle rack of a preheated oven (140 degrees) and let them remain overnight. When you think they may be dry, remove one or two. Let them cool, and test them for moisture. If they still have water in them, let the fruit dry for another hour or so. Then test. If the grape is pliable and chewy, remove the rest from the drying tray. You have raisins! How and why is the grape now preserved? When you dry out the grapes, you are taking away the moisture that fungi need to grow. If fungi are allowed to grow the grape will rot. As long as the dried fruit can't take in moisture from the air, it will stay edible for many months! Information adapted from: Simple Kitchen Experiments by Muriel Mandell, copyright date 1993, by Sterling Publishing Company Inc.
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