Belmont Specialty Cakes in Belmont Citi Centre was fined $1320 by the NSW Food Authority for selling gluten-free friands on April 8 this year that actually contained gluten.

Gluten is a protein found in wheat, barley, oats and rye that is harmful to people with gluten intolerance or coeliac disease.

The genetic disease can cause serious problems in the stomach and intestines, and if left untreated can mean people do not absorb their food.

The owner of the cake shop, listed as Jackie Tram Pty Ltd, was also fined $660 for failing to take all necessary steps to prevent the likelihood of food being contaminated during processing on April 14 this year.

A NSW Food Authority spokesman said the authority had responded to a complaint by a customer who had asked for gluten-free food and had a reaction to one of the offending friands.

Authority officers bought a sample of the advertised gluten-free foods and sent them to a laboratory for analysis, which came back positive for gluten and resulted in the fine.

"We do regular surveys of category items and did a gluten-free survey late last year, which was very successful," he said.

Belmont Specialty Cakes' owner declined to comment.

The information was listed on the NSW Food Authority's website as part of a policy of naming and shaming.