Soda bread is a type of quick bread in which baking soda has been substituted for yeast. The ingredients of traditional soda bread are flour, baking soda, salt, and buttermilk. Other ingredients can be added such as raisins or various forms of nuts.
The buttermilk in the dough contains lactic acid, which reacts with the baking soda to form tiny bubbles of carbon dioxide. Soda bread can dry out quickly and is typically good for two to three days; it is best served warm or toasted. In Ireland, typically the flour is made from soft wheat; so soda bread is best made with a cake or pastry flour (made from soft wheat), which has lower levels of gluten than a bread flour.
Various forms of soda bread are popular throughout Ireland. Soda breads are made using either wholemeal or white flour, with the former known colloquially as "brown bread" in the Republic of Ireland. In Northern Ireland the wholemeal variety is known as "wheaten bread" and normally sweetened, while the term "soda bread" is restricted to the white savoury form normally served fried. The two major shapes are the loaf and the "griddle cake", or farl in Northern Ireland. The loaf form takes a more rounded shape and has a cross cut in the top to allow the bread to expand. The griddle cake or farl, is a more flattened type of bread. It is cooked on a griddle allowing it to take a more flat shape and split into four sections.
Soda bread dates back to approximately 1840, when bicarbonate of soda was introduced to Ireland. Because the climate of Ireland hinders the growth of hard wheat (which creates a flour that rises easily with the assistance of yeast), bicarbonate of soda replaced yeast as the leavening agent.
There are several theories as to the significance of the cross in soda bread. Some believe that the cross was placed in the bread to ward off evil. It is more likely that the cross is used to help with the cooking of the bread or to serve as a guideline for even slices.
Soda bread eventually became a staple of the Irish diet. It was, and still is, used as an accompaniment to a meal.
The Soda Farl is an important part of the Ulster fry of Northern Ireland.