Ultrasound-assisted rehydration for acrylamide mitigation in carrot enriched breads? A critical assessment

Two qualities of commercially available dried carrot strips (Q1, Q2) were analyzed for their rehydration properties, sugar/polyphenol diffusion, and acrylamide formation in subsequently baked yeast-leavened wheat breads. Ultrasound-assisted rehydration and conventional soaking were applied, and the water absorption was fitted using ExpAssoc and Peleg's models. Both models were appropriate and accurate to describe rehydration behavior of carrot strips, with R² > 0.996 for ExpAssoc and R² > 0.898 for Peleg model. Furthermore, the Peleg's model was also successfully used to fit the sugar and polyphenol diffusion during rehydration. For baking trials, rehydrated carrot strips (45 g/100 g flour) were used, and water addition to the dough was kept constant at 111 g/100 g flour (Q1) or 151 g/100 g flour (Q2). Ultrasonic and sonotrode treatments increased final water binding in carrot strips after 85 min compared to soaking alone. Overall, increasing the treatment temperature and reducing the particle size led to higher diffusion rates. Acrylamide analyses (HPLC-ESI-MS/MS) demonstrated that rehydration strategies reduced acrylamide levels in carrot-enriched breads by up to 75 % when the rehydration water was discarded due to leaching of precursors. This resulted in breads with acrylamide concentrations ranging from 10 to 18 μg/kg. Also, breads in which rehydration water was used for baking demonstrated the potential for lowered acrylamide content. Despite mostly significant (p < 0.05) changes in lightness, specific volume, crust/crumb moisture and thickness, breads with hydrated carrot strips still demonstrated good baking qualities. Summarizing, both ultrasound-assisted hydration and conventional soaking proved to be effective strategies for reducing acrylamide formation in carrot-containing baked goods.