THE so-called “big four” UK supermarkets have slumped to the bottom of an annual ranking after disappointing customers with the quality of their food and ability to keep up with online rivals.

Asda, Morrisons, Sainsbury’s and Tesco fell to the bottom five places along with Iceland for their in-store offerings in the Which? survey after scoring poorly for their produce and own-label lines.

Discounters Aldi and Lidl outperformed the big four with scores of 68% and 66% respectively. Both also received five stars for value for money.

Asda achieved the lowest score of 56% for in-store shopping and 65% for online shopping as it managed just one star for the quality of own-brand items and two stars for fresh produce.

Some 55% of Asda’s online customers had received a substitution with their last order, including parsley replacing basil, potato gratin instead of macaroni cheese, and red wine vinegar replaced by a bottle of red wine.

Tesco scored just above Iceland and Asda at 59% for its in-store offering. It achieved just two stars in the value for money section, with some survey respondents reporting concerns that it was becoming more expensive. However, it performed better for online shopping with a score of 71%.

Sainsbury’s achieved 63% for its in-store offering and 69% for online shopping, but customers awarded it only two stars for value for money in both categories.

Morrisons won the highest scores of the big four at 64% for in-store shopping and 70% for online but was let down by the two-star rating of its own-label products.

Iceland came second to bottom in the ranking with a score of 57% for in-store shopping. However, the popularity of its online offer took it to second place with a score of 79%.

Waitrose topped the table for in-store shopping, receiving five-star ratings for store appearance, queuing time, staff availability and range of products but achieved just two stars for value for money.

Which? Magazine editor Harry Rose said: “Our survey shows that while the big four are failing to consistently give customers the high-quality experience they deserve, both in-store and online, no supermarket is getting everything right.

“People today have more choice than ever on where to do their food shop and staying loyal to one supermarket has become a thing of the past. The big supermarkets really need to up their game if they’re going to keep their customers coming back.”

Which? surveyed more than 12,000 consumers for the study.