Cereals are a good source of phenolic acids, most of which are present in bound form. The aim of this study was to develop a method for quantifying total phenolic acids in cereals that includes a robust step for hydrolysis of bound forms. Different hydrolysis procedures were evaluated. Acid hydrolysis, even with subsequent use of enzymes, proved unsuitable for releasing bound phenolic acids from the cereal matrix. Base hydrolysis (3 M, 90 min) resulted in the highest extractability, with average recoveries of 88–108% for cereal phenolic acids. The phenolic acid content in cereals (two cultivars each of rye, barley, and oats, and eight cultivars of wheat) varied up to 2-fold between cereal genotypes and 1.5-fold within genotypes. The highest content was found in rye, followed by wheat, barley, and oats. Ferulic acid dominated in all cereals, amounting to 48–72% of total phenolic acid content.

Sourdough bread is highly enjoyed for its exceptional flavor. In contrast to bread crust, which has been investigated intensively, the knowledge on bread crumb is rather fragmentary. In this study, the taste-active compounds of sourdough bread crumb were identified and quantified. By means of recombination experiments and omission tests, the authentic flavor signature of sourdough rye bread crumb was decoded and recreated with ten key tastants and eleven key odorants. Based on the final taste and aroma recombinants, a fast and sensitive ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method using stable isotope dilution analysis (SIDA) was developed and validated. Due to prior derivatization using 3-nitrophenylhydrazine (3-NPH), key tastants and odorants in bread crumb could be quantified simultaneously in a single UHPLC run. The identified key flavor compounds in combination with the developed UHPLC-MS/MS method could offer the scientific basis for a knowledge-based optimization of the taste and odor of sourdough bread.