Bread flour is a high-gluten flour made from hard wheat. It has 12% - 14% protein content and contains very small quantities of malted barley flour and vitamin C or potassium bromate, which are added to it externally. The barley flour enhances the function of the yeast, and the other additives increase the elasticity of gluten, which enables it to retain carbon dioxide released by the yeast as the dough rises and bakes. This flour has more gluten because of the high protein content, and so holds more carbon dioxide from the yeast to make firm, chewy and fluffy breads. It comes in white, whole wheat, organic, bleached, and unbleached forms and is sometimes conditioned with ascorbic acid, which improves its concentration and gives it a better texture. Bread flour is best used to make bread, pizza dough, baguettes, and pretzels. It is usually used as a prime ingredient in rye, barley and other mixed-grain breads, where an extra lift is required to boost the other grains. It should not be used in other types of cooking (say, to make a banana bread which usually has a cake-like texture, or even "quick" bread) unless a recipe particularly calls for it, as it may alter the texture of the final product, making it tough, dense and even sticky depending on the ingredients used. Bread flour and all-purpose flour weigh differently, so while substituting, keep this in mind.

• Bread Flour: 1 cup (140 grams or 5 ounces)
• All-purpose Flour: 1 sifted cup (125 grams or 4½ ounces)

Generally, flour varies in both the quality and quantity of the gluten it contains, as different strains of wheat from varying regions and growing seasons have different gluten profiles. However, for bread flour substitution, all-purpose flour can be used, as it forms a typical blend of hard and soft gluten wheat which works well in nearly all flour recipes. It has a protein content varying from 11% - 14%, and is thus the perfect substitute. Sometimes, the results won't be as spectacular as you may have hoped and it may produce a dense, flatter bread. To deal with this issue, you may supplement the all-purpose flour with wheat gluten to the tune of 2 teaspoons per cup of flour. If you are not confident about adding the gluten, you may try this technique known as autolysis to get more out of the gluten already present in the all-purpose flour.

• Start by combining the flour and water as mentioned in the recipe, but don't start kneading it.
• Allow it to rest for about 20 - 25 minutes.
• Add in the salt, yeast, and other ingredients.
• Knead thoroughly to make the dough.

The 20-minute resting period activates the gluten and gives it enough time to start working, thus producing you a lighter, firmer bread. This method may be used even with bread flour to get a better final product. Whether it is bread flour or all-purpose flour, our ultimate aim is to prepare a delicious bread with a pleasing texture. Bread flour is readily available in grocery stores, and ideally, if a recipe demands bread flour as a main ingredient, it should not be replaced or substituted with any other flour. However, in situations when you don't have a choice but to use a substitute, all-purpose flour, if added in the right proportion, can help you achieve a similar final product.