Sourdough-based microorganisms and metabolites in nutraceutical and pharmaceutical products

Bread is considered a universal food by many. Nowadays, all countries around the world have a baked product-based culinary tradition. In fact, the bread is a symbol of culture, history, and wealth. According to historians, the bread story began 30, 000 years ago in ancient Egypt. It extended across Europe, Asia, and America establñishing the framework for modern society and inspiring the rise of many civilizations. Bread is an excellent source of complex carbohydrates that provide the human body with energy and play an important role in regulating the blood glucose level. Sourdough is the oldest form of leavened bread. It was probably discovered by accident when bread bran was mixed with flour and water; the left dough developed a lighter texture and better taste due to the bran microorganisms' fermentation. Despite ignoring the mechanisms behind fermentation, sourdough preparation knowledge has been inherited from generation to the present day. The sourdough bread's main ingredient is the starter, which consists of dough containing wild lactic acid bacteria and yeast. The bacterial fermentation induces the production of lactic acid that imparts a sour taste and inhibits the growth of foodborne pathogens. Whereas the yeast's role is mainly the production of carbon dioxide, which causes the bread to leaven. Sourdough-baked bread is mainly composed of healthy carbohydrates, protein, fiber, vitamins, minerals, and other prebiotics. It is known for being a healthy food, more digestible and nutritious. Additionally, the presence of prebiotics is good for the intestinal microflora growth. This chapter aims to present sourdough bread, its preparation steps, ingredients, microbial constitution, and nutritional values. It also aims to discuss relevant literature on sourdough technology and present the most recent trends in this field.