The tub of the lentil-flavoured dip did not have a plastic cover on it, so the date of consumption was printed directly on the food.
The owner of the contaminated snack, Miriam, who describes herself as from Madrid, a vegan and an animalista, shared her confusion online.
Tagging the budget supermarket on Twitter, she said: “I just bought lentil houmous in Mercadona and when I opened it at home I realised that it was not covered, and that the date is printed on the houmous itself.”
Her tweet garnered over 5,000 retweets and more than 14,000 likes.
The Valencian retailer, chaired by Juan Roig, replied to Miriam in a statement, saying it ‘apologises for what happened’.