Effect of a commercial peptidase on volatile composition and sensory properties of wheat bread crumb and crust

Flavourzyme is a commercial peptidase, primarily exhibiting exopeptidase activity. The effects of Flavourzyme addition (0-1.6 g/kg, flour basis) on chemical composition, volatile profile and sensory properties of bread crumb and crust were systematically studied. Free amino acids (from 999 to 2156 mg/kg with 1.6 g/kg Flavourzyme addition) and trichloroacetic acid-soluble small peptides in dough remarkably increased with Flavourzyme addition. Gas chromatography-mass spectrometry analysis revealed that 3-methyl-1-butanol, 3-(methylthio)-1-propanol, 2-phenylethanol, acetoin and indole enhanced in crumb after Flavourzyme addition. Meanwhile, pyrazines, benzaldehyde, 5-methyl-2-furanmethanol, maltol and 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one accumulated in crust. Descriptive sensory analysis revealed that the cheesy and alcoholic notes of crumb and the caramel, toasted and nutty notes of crust were strengthened with Flavourzyme addition. The Flavourzyme hydrolysis products enhanced yeast activity in fermentation and facilitated Maillard reactions in baking, leading to the accumulation of related volatile compounds. These compounds subsequently modified the aroma properties of crumb and crust.