Yes, you read that right - there are microscopic needles in the fruit that you are eating! OK, it isn't as dire as that sounds, but it is an interesting phenomenon to study under a Foldscope. I wrote a blog about this (you can click here to read it), but I figured I would also include some of the pictures here, too.

The needles are actually crystals of calcium oxalate. And although they are needle shaped, it is important to remember that they are microscopic. The reason for the irritation is because there is an enzyme called bromelain that breaks down the protective mucous layer lining your mouth leaving it vulnerable to the fruit's acidic juices (and the calcium oxalate crystals).

It is fascinating to learn about how something microscopic can impact you on a macroscopic scale!

Enjoy some fresh pineapple as you take a look at these Foldscope images!!

Calcium oxalate crystals in pineapple juice viewed with increasing levels of magnification (50X - left, 140X - middle, and 340X - right)



Calcium oxalate crystals viewed with brightfield (left) and darkfield (right) lighting at 140X magnification