Starch is the energy store of plants, made of long chains of glucose called amylose and amylopectin. Food starch is extracted from potatoes, corn (maize), wheat, cassava or rice by grinding the plant and washing the starch granules away from the fibre and protein, which leaves a fine, white, almost tasteless powder.
When starch is heated with water its granules swell and gelatinise; when the dough is then fried or baked the water escapes, leaving a crisp, airy structure. That is why starch is a key ingredient in shaped crisps such as Pringles - Cheesy Cheese, which are made from a dough of dried potato, corn flour and starch. It also appears in Goody - Crispy Chilli, alongside fried chillies, sesame and cumin.
A label that just says “starch” does not show the source. The Thai-language labels of some Pringles flavours name it as wheat starch, which counts as a wheat ingredient and contains traces of gluten.
This page also groups the starches that labels name by their source or treatment: corn, tapioca and wheat starch, modified and oxidised starches, dextrins and maltodextrin. Every snack that contains any of them is listed here.
