The research was published in the current edition of the European Journal of Prosthodontics and Restorative Dentistry.

A study at the University of Dundee in Scotland has found that cooked vegetables can be as acidic as soft drinks. Cooking them in certain ways can make them as acidic as tooth-eroding soft drinks, scientists have said.

Vegetables that ranked highest in acidity after cooking (roasting) are eggplants, green capsicums and zucchinis, while stewed red capsicums become heavily acidic. The acidity level of onions or tomatoes does not change with the cooking method.

Head researcher Graham Chadwick said: "The acidity of ratatouille prepared by oven-roasting is the same as that of some carbonated drinks that, when consumed in excess, are believed to contribute to the development of dental erosion."

Dental erosion is believed to be caused by the direct contact of teeth with acid, which destroys tooth tissues.