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The Physics of Wotsits

What I discovered when I did that was actually people didn’t really understand starch.

Why do I like this?  I think because it’s one way of making sense of things.  So as a microscopist I look at the packing: how molecules and larger structures pack together.  And then you want to know how that impacts on the end products, and that might also include how the structure changes during processing.  So, to give you a specific example, one of the first things I did in a food-related material was look at what you might call cheesy Wotsits.  So these were what you might more technically call an extruded starch foam.

So you put starch in at one end of an extruder, which is a thing used for plastics in general.  So you put starch grains and you put water and you put it through the extruder which has a lot of heat, a lot of mechanical input, and out comes a product at the other end.  Now, you need to know you’re not going to break your teeth on it if it’s a cheesy Wotsit, you need to know that it’s not going to disintegrate instantly.  And so how the structure changes due to the processing conditions will impact what comes out at the end.  And it’s a very complicated kind of thing!  And what I discovered when I did that was actually people di’t really understand starch well either.  So I started then, instead of looking at the processing end of it, started looking at the structure of the starch itself and got increasingly involved with more biological aspects.

So we were looking at the internal packing of a granule.  So if you tease starch out of something like wheat or maize, you will have spherical granules that come out, some tens of microns in size depending on the species.  And inside that the molecules are packed in a very specific way, and it’s a very complicated way, and there are several different molecules in there which are important.  So, two different polysaccharides which are known as amylose and amylopectin
and they pack in different places.  And we discovered that there was a kind of universality in the structure of the packing.  So there was a certain periodicity in the way that starch was laid down, in the way the molecules were laid down.  And that’s when we really started talking to the plant biochemists to try and understand what gave rise to that universality.  And, I have to say, we never really solved it, but it was great fun trying!