Supermarkets using cheaper ingredients in own-brand pesto

Which? investigation finds standard ranges using cashew nuts instead of pine nuts, and parmesan substitute

An investigation into supermarket own-brand pesto has found that bamboo fibres, potato flakes and nut flour are being used as cheaper alternatives to traditional ingredients.

Pesto, which is traditionally made from basil, pine nuts, parmesan, olive oil - and sometimes lemon juice and garlic - has become a staple food in the UK.