Digestion starts in your mouth as soon as you start to chew. Your saliva is full of enzymes. They are a kind of chemical key that unlock chains of protein, fat, and starch molecules. Enzymes break these chains down into smaller molecules like sugars and amino acids.


In this experiment, we will examine how the enzymes in your mouth help to break down the starch in a cracker. You will test the cracker to confirm starch content, then put it in your mouth and chew it for a long time in order to really let the enzymes do their job. Finally you will test the cracker for starch content and see what has happened as a result of your chewing.


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7 Responses to “Testing Spit Samples”

  1. We first picked the spit testing experiment (chewed up crackers) using iodine to test for starch. At first, we used Lugol’s 2% iodine and both spit samples were not turning blue-black. Then, we used providone-iodine, which is like a 10% solution, but only 1% available iodine. The chewed up cracker turned blue-black with it. Strange. Just shows you how science can give you lots of puzzles to think about.

    Thank you for being so passionate about science! It’s inspiring to me as a parent.
    Michelle

  2. It should still work – give it a try and let me know how it goes.

  3. Opal and Flora Radding says:

    Our Iodine is clear in in the bottle. Does this mean it won’t work? Where can we find the orange iodine like in the video?
    Thanks

  4. First, make sure your iodine is working right. Put a drop of iodine on a pile of starch (like cornstarch, or cut a potato open and drop iodine on the exposed half). It should change color to dark blue. This is what makes iodine a starch indicator. Next, try chewing for longer… a lot longer than you think. Then have a friend do the same and compare. If that still doesn’t work, try a different cracker!

  5. Heather Henry says:

    I followed the directions twice with two different types of starches one was a saltine and the other a noodle.The color of the iodine on the two I chewed up was the same as the color of the iodine on the one that was mixed with water.

  6. Yes, well it is science… sometimes that happens!

  7. Lydia Fancher says:

    the spit sample looked like poop… eww… o_o