According to a study at Scotland's University of Dundee, eggplants, green capsicum and zucchini become more acidic when roasted in the oven, while red capsicum becomes heavily acidic when stewed. But the study says that the acidity of onions or tomatoes does not change with the cooking method.
Publishing his findings in the current issue of the European Journal of Prosthodontics and Restorative Dentistry, Dr Graham Chadwick said that the study was prompted by reports that people on a vegetarian diet may be at risk of dental erosion. This is because the large quantity of foods that they eat, such as fruit and vegetables, tend to be quite acidic. So the researchers have studied how different methods of cooking vegetarian dish like ratatouille could affect its acidity.
Ratatouille was acidic no matter how it was cooked, but it was noticed that oven roasting significantly increased the acidity of the dish, compared with stewing. Dr Chadwick explained that the acidity of ratatouille prepared by oven-roasting is almost the same as that of some carbonated drinks that, when consumed in excess, are believed to contribute to the development of dental erosion.