Cashews can occasionally produce a tingling or 'fizzing' sensation due to residual compounds from their processing. Raw cashews contain a caustic substance called urushiol in their shells, which must be removed through heat treatment. If trace amounts of these irritants remain, they can react with saliva, creating a perceived fizz.

why do cashews fizz

The Science Behind It

The "fizzing" sensation sometimes experienced with cashews isn't a true effervescence but rather a chemical reaction on the tongue. Raw cashews are encased in a double shell containing cashew nut shell liquid (CNSL), which includes anacardic acid, cardol, and cardanol—compounds related to urushiol, the irritant in poison ivy. To make cashews safe for consumption, they undergo a rigorous heat treatment process, typically roasting or steaming, to break down and remove these caustic substances. However, if the processing is incomplete or if trace amounts of these potent irritants persist on the nut's surface, they can react with the moisture and enzymes in saliva. This interaction can stimulate nerve endings in the mouth, leading to a distinct tingling, burning, or "fizzing" sensation, often mistaken for carbonation. Ensuring proper processing is crucial to eliminate these naturally occurring irritants and guarantee a pleasant eating experience.

Fun Facts

The cashew 'nut' is technically the seed of a fruit called the cashew apple, which is also edible.
Cashew nut shell liquid (CNSL) is a powerful natural chemical used in industrial applications like resins, coatings, and brake linings.