The shocking secret of supermarket chicken

Sarah Coles
Chicken dish
Chicken dish

A report has revealed that up to 18% of some of the chicken sold in some supermarkets isn't chicken at all. It's an ingredient added to the chicken breasts in a factory - which bulks up the weight of the breast dramatically. The process is perfect legal, and affects chicken sold in five UK shops and supermarkets.

So what is the ingredient, and is this the worst supermarket trick in the book?