Sainsbury’s has had to tell its customers its own-label chocolate mousse is no longer suitable for vegetarians after temporarily changing the recipe to include pork gelatine.

The retailer has added a ‘not suitable for vegetarians’ logo to its six-pack of 62.5g BySainsbury’s mousses and put up shelf barkers alerting shoppers to the change in-store.

The barkers state that it had changed the recipe “due to unforeseen circumstances” and that it was “working closely with our supplier to revert back to a vegetarian recipe as soon as possible”.

“We have sold own-label chocolate mousse for a number of years,” said a spokeswoman. “We started working with our supplier to change the recipe to make it suitable for vegetarians and this mousse was on sale for some months last year. But we are still in the process of ensuring the quality and taste of this recipe so have reintroduced the use of gelatine.”

When a previously vegetarian-friendly product reverts to a non-vegetarian recipe, it can spark a consumer outcry. By being transparent about the recipe change, Sainsbury’s is hoping to avoid the consumer backlash faced by Mars in 2007 when it was forced to make a hasty u-turn after it changed the recipe of a number of its products including Mars bars, Snickers, Twix and Maltesers to contain animal rennet.

Sainsbury’s move comes at a time when food labelling is coming under unprecedented levels of scrutiny from the horse meat scandal.