Interaction of wheat macromolecules and berry pomace in model dough: Rheology and microstructure

The incorporation of dried black currant pomace (BCP) in wheat dough is a possible way to increase the sustainability of the production chain by adding value to a by-product from juice processing that is up to now regarded as waste. The partial replacement of wheat flour by dried black currant pomace (BCP) increased the water absorption of dough and dough development time. Small strain oscillatory rheology showed that dough stiffness increased with increasing levels of pomace addition (G' at 1 Hz was 8.2 kPa for the reference, and 49.7 kPa for dough with 30% BCP). This result is supported by the higher dough stability observed in farinograms. After simulated baking, dough with 30% BCP showed higher storage and loss moduli compared to the reference and to dough with lower levels of BCP. The increased structural strength that comes with increasing pomace levels is explained by interactions with gluten matrix through hydrogen bonds. The gluten is less developed through the existence of BCP which results in a lower stickiness, resistance and extensibility of the dough. Scanning electron microscopy and fluorescence light microscopy images showed the disruption of gluten film by fibre incorporation. Considering those influences on dough properties, it can be reasoned that dough with 10% BCP would produce products with satisfying characteristics, whereas higher application levels cannot be recommended without using additives to increase the gluten strength. (C) 2017 Elsevier Ltd. All rights reserved.