Determination of Lactic and Acetic Acids and Estimation of Their Molar Ratio

Lactic and acetic acids concentrations and their molar ratio (defined as quotient of fermentation, QF) are important indicators to describe the sourdough features. Such organic acids, produced by lactic acid bacteria (LAB) during fermentation, are responsible for lowering the pH, and, consequently, for sourdough structure, sensory attributes, antifungal properties, and preservation. QF has also relevant effects on sensory characteristics, flavor, and shelf life of leavened baked products such as bread. In the chapter introduction, different available methods to determine lactic and acetic acids in sourdough are briefly listed highlighting advantages and limitations of each approach. Then, the procedure for the detection and quantification of lactic and acetic acids through high performance liquid chromatography (HPLC) analysis and for the calculation of QF is detailed.