[Bio60_2019] Colombian Raisins

When I came to the U.S., I decided to bring some snacks with me from back home.

When I got the foldscope, I decided to look at some raisins I had brought with more detail to see if I could lean anything interesting.

To observe the raisin, I used tweezers to break the raisin apart, then picked up a small piece from the inside, and then smeared it onto the plate. Using the cover slip, I further spread out the sample, so it became more translucent. To take a picture, I used the light source from the kit and the camera on my Samsung S4.

To my surprise, when I looked at the sample, it looked green, not magenta! The fact that green is the complementary color of magenta probably has something to do with this. Perhaps the raisin absorbs wavelengths of light associated with green, so when viewed normally, we see its complementary color, while when viewed with the foldscope, only light that can be absorbed and re-emitted on the other side can be seen.

There were also a lot of circular shapes that appeared to be bubbles. Maybe these are pockets of air that were trapped when the sample was pressed against the plate. Reading online about raisins, I learned that it is possible for the sugars to crystallize, so perhaps some of the large shapes are sugar crystals.

It would be interesting to compare these images to ones taken from grapes, to see if or how they differ.

Leave a Reply