Improving rye bread antioxidant capacity by bread-making methodology: Contribution of phosphate-buffered saline- and methanol-soluble phenolic phytochemicals with different molecular profiles

Abstract

Bread antioxidant properties may be considerably modified in the bread-making process. To indicate the bread-making methods that may boost its antioxidant properties, five bread types were produced by straight dough and sourdough methods from seven rye cultivars. Their antioxidant, chemical and molecular characteristics were investigated in PBS and MeOH extracts. Free and conjugated phenolic acids (esters and glucosides) predominated in both extracts. Nevertheless, PBS-soluble fractions also comprised feruloylated arabinoxylans (69–83 μg/g and 28–29 mg/g of bread, for ferulic acid and arabinoxylan, respectively) with high molar masses (443000–556000 g/mol). They showed markedly higher concentration of Folin-Ciocalteu reactive components and two times higher ABTS•+ scavenging capacity than MeOH-soluble ones. These parameters were significantly correlated with bread acidity and arabinoxylan-esterified ferulic acid content. Consequently, rye bread with the lowest pH, obtained by a straight method with lactic acid addition, exhibited substantially increased antioxidant capacity, owing to the most efficient hydrolysis of highly feruloylated water-unextractable arabinoxylans during bread-making. This study showed that macromolecule-bound ferulic acid present in physiologically relevant PBS extract of rye bread is a stronger antioxidant than much more abundant low molar mass phenolics extracted with MeOH. Thus, PBS extract might better reflect antioxidant potency of cereal-based products.