Phenolic Compounds and In Vitro Antioxidant Activity

Phenolic compounds (PCs) are mainly responsible for the antioxidant capacity of bread, which is affected by several factors such as the type of flour, microbial dynamics, endogenous and exogenous enzymes, processing conditions, and interactions between PCs and other dough components. During sourdough fermentation, PCs undergo significant modifications via endogenous cereal enzymes and microbial metabolism. This results in increased free PCs, hydrolysis of esters of phenolic acids, and conversion of flavonoid glycosides to the corresponding aglycone. In vitro colorimetric assays are simple and versatile tools for measuring the amount of PCs in bread and their antioxidant capacity. They are also utilized for investigating the effects of fermentation and baking on PCs profile. This chapter will describe the most common assays implemented for bread analysis, focusing on the association between antioxidant activity and PCs. This chapter will also describe the methods for extracting free and bound PCs from bread, as well as Folin–Ciocalteu assay, DPPH and ABTS+ scavenging assays, and ferric ion reducing antioxidant power (FRAP) assay on microplate or cuvette scales.