What are commercial meat tenderizers, like the ones in the spice aisle of the grocery store, made out of?.Papain and bromelain are often called natural "meat tenderizers." Why is this? What does it mean? How do they tenderize meat?.Which fruits contain papain, bromelain, or another protease?.What do proteases do? Why are they considered enzymes?.Does this allow the gelatin to solidify or not? Ready to find out? If so, get out your spoon, because with this science fair project, you will get to enjoy some of your results as dessert! The heat will permanently inactivate the fruit's protease. In the case of eggs (and most proteases), denaturation of the protein causes an irreversible change. When the egg is raw, the egg white- which has lots of proteins, called albumins- is transparent and liquid but after cooking, it becomes opaque and solid. A good example of this process is cooking an egg. Exposure to heat is one method of denaturing proteins. Denaturation changes the structure, or shape, of the protein, without changing what it is made up of. Most proteins can be inactivated using a variety of methods. Remember that proteases, like papain and bromelain, are also proteins themselves. You might be wondering how you will possibly inactivate the protease yourself. In this food science project, you will see for yourself whether one of these protease-containing fruits interferes with gelatin's ability to solidify and, if it does, you will test whether it is the protease that interferes with solidifying by inactivating the protease (which means to make it stop working) in the fruit and then adding the fruit to the gelatin. In this science project you will investigate whether the proteases are responsible for the gelatin not solidifying. Pineapples contain special enzymes called proteases. Some fruits, like strawberries (on the left), allow gelatin to solidify around them, while others, like pineapple (on the right), do not allow the gelatin to solidify. Could it be that the papain and bromelain in these fruits are cutting the gelatin proteins into such small pieces that they are no longer able to tangle together and create a solid structure? This is exactly the question you will tackle in this science fair project. Proteases specifically act like a pair of scissors, helping reactions take place that cut other proteins up. Proteases are enzymes, which are a special group of proteins that help make certain chemical reactions happen. It turns out that this second group of fruits all contain proteases (pronounced PROH-tee-ay-siz), like papain (pronounced puh-PIE-uhn) and bromelain (pronounced BROH-muh-lin). Figure 2 below shows some of these fruits in an orange gelatin dessert. But if you add fruits like pineapple, guava, mango, or kiwi, you end up with a runny mess that never solidifies. What happens when you add fruit to your gelatin? Some fruits, like strawberries, oranges, and apples, are a tasty addition the gelatin solidifies around the chunks of fruit. The end result is a wiggly-jiggly solid to enjoy. When the gelatin is cooled, the proteins remain tangled. As the gelatin proteins tangle, they form mesh pockets that trap the water, sugar, and other flavoring agents that you have added to your dessert. These long, thin, flexible proteins tangle up with one another, the same way strands of cooked spaghetti do when they are all in one pot together. The collagen proteins in the gelatin are like microscopic (meaning too small to see with just your eyes) strands of spaghetti. When you make a gelatin dessert, you dissolve the gelatin mix in hot water. Gelatin is a mixture of collagen proteins that have undergone a chemical reaction that makes them able to solidify when you are cooking with them. Collagen can be found in many parts of your body, including your skin, bones, muscles, and cartilage. Collagen is a structural protein found in all animals, meaning that it helps give animals their structure, or shape. Your skin, your blood, your hair- all of these are made up of many different types of proteins. Proteins are a basic type of matter that make up all living things.
Gelatin is made from a protein called collagen. This is because including these fruits can make it difficult for the gelatin to solidify. When making a gelatin dessert, the packaging may recommend against using certain fruits, like papaya (shown on the left here) and pineapple (shown cut up on the right).
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