Scald Fermentation Time as a Factor Determining the Nutritional and Sensory Quality of Rye Bread

This study investigates the effect of extended rye scald fermentation times (12-48 h) on its biochemical properties and rye bread's nutritional and sensory qualities. Traditional rye bread production in Latvia involves prolonged fermentation with lactic acid bacteria (LAB), a process that influences the bread's acidity, sugar content, and concentrations of organic acids, fructans, and phytates. Scald fermentation was analyzed at intervals of 0, 12, 24, 36, and 48 h to monitor microbial activity, particularly LAB population dynamics. Organic acids and sugar profiles were analyzed using HPLC, while phytic acid and fructan concentrations were determined using the Phytic Acid Assay Kit (K-PHYT) and Fructan Assay Kit (K-FRUC). Sensory evaluation assessed attributes including aroma, sour and sweet taste, stickiness, and floury aftertaste. A rapid pH decrease and increased total titratable acidity (TTA) after 12 h confirmed scald's suitability as a substrate for Lactobacillus delbrueckii metabolism. Lactic acid content increased 13.8-fold after 48 h. Combined scald and dough sourdough fermentation reduced phytic acid by 20% and fructans by 49%, improving mineral bioavailability. Extending fermentation beyond 24 h showed no significant differences in physicochemical parameters, although it improved sensory quality, reduced stickiness, balanced sweet-sour flavors, enhanced aroma, and minimized floury aftertaste.