The switch will remove the use of 775 tonnes of plastic a year.

It will be rolled out on the supermarket’s own-brand mushroom range by the end of January.

Sainsbury’s said it would become the first UK retailer to use cardboard punnets for all mushrooms across all stores.

The punnets still have a film outer packaging, which can be recycled at Sainsbury’s in-store recycling points for flexible plastics.

Director of product and innovation Claire Hughes commented: “As part of our Plan for Better commitments, we are trying to reduce plastic packaging across our own brand ranges.

“We are delighted to introduce cardboard punnets for our own-brand mushrooms. Making a collective effort with suppliers to increasing recycled content and recyclability for all customers has helped achieve our biggest ever plastics removal so far. The initiative reflects our commitment towards a healthier and more sustainable future as we continue to look at ways to innovate our packaging and reduce and replace plastic where possible.”

Sainsbury’s said the new fully recyclable cardboard trays would help customers to both cut down on plastic and recycle more at home.

The business has committed to reducing its use of plastic packaging by 50% by 2025, while also supporting the circular economy through recycling.  

In its baseline year (2018 for food and 2020 for general merchandise) the figure was 69,839 tonnes. It had reduced to 57,624 tonnes in 2022. 

Last year Sainsbury’s also switched from plastic to paper wrapping on all its own-brand kitchen and toilet roll products, in a move that saved 485 tonnes of plastic a year.

It has pledged to invest £1bn over the course of 20 years, in order to become Net Zero across its own operations by no later than 2035.