Thirty years of knowledge on sourdough fermentation. A systematic review

Background: Sourdough is one of the oldest examples of natural starters, mostly used for making fermented baked goods as an alternative to baker's yeast and chemical leavening. Almost 30 years of research have accumulated showing its performance. Time is mature to elaborate collectively these data and to draw conclusions, which would represent milestones for scientists, industries and consumers. Scope and approach: With the scope of highlighting its microbiological, biochemical, technological and nutritional potential, we used “sourdough” as the only keyword and the PRISMA flow diagram to retrieve, select and systematically review 1230 peer reviewed research articles from four databases (Google Scholar, Scopus, PubMed and ScienceDirect). Key findings and conclusions: The literature states that sourdough baked goods underwent characterization in almost 50 countries and all continents, mainly dealing with salty (breads and substitutes) and sweet products. Converging data defined optimal use conditions, most common microbiological and biochemical characteristics, criteria for selecting and re-using starters, and versatility of sourdough for making baked goods with a relevant number of flour species/varieties and agro-food by-products. Because of the unique microbial composition and functionality, sourdough has claimed as an irreplaceable starter for improving the sensory, rheology and shelf life attributes of baked goods. The most recent literature showed how the sourdough fermentation mainly increased mineral bioavailability, enabled fortification with dietary fibers, lowered glycemic index, improved protein digestibility and decreased the content of anti-nutritional factors. This knowledge is solid for delivering to industries and consumers, and to face new research challenges starting from a consolidated state of the art.