My two favourite breakfast cereals are Shreddies and Weetabix. When I鈥檝e finished, the remnants in the bowl look similar, but I can always tell which was which: a Shreddies bowl can be washed up quite easily, while Weetabix clings like cement. Why the difference?
鈥� As a lifelong consumer of Weetabix, I feel qualified to answer this question. Both Shreddies and Weetabix contain a high proportion of starch, which can form an adhesive paste with water. This phenomenon is well known to bookbinders because it is used to make paper.
Starch consists of a mixture of amylose and amylopectin, polymers that can absorb water to form a gel. As the gel dries, the water is expelled and bonds between the molecular chains reform, creating a semi-crystalline 鈥渃ement鈥� which will adhere to any adjacent surface.
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This effect is much more noticeable with Weetabix than Shreddies simply because Weetabix is made of fine flakes of cereal compressed together, while Shreddies are made from longer strands. That means Weetabix has a greater surface area of adhesive in contact with the bowl, making it more difficult to clean.
Chris Sugden, London, UK
鈥� I have no experience of Shreddies, but am familiar with the Weetabix problem. So while I don鈥檛 know the difference between the properties of the two cereals, I can give this advice to your correspondent. Soak the used Weetabix bowl for a few minutes, rather than a few seconds, before cleaning 鈥� it makes it much easier.
David Purchase, Bristol, UK