ORIGINAL PAPER Rheological Analysis of Wheat Flour Dough as Influenced by Grape Peels of Different Particle Sizes and Addition Levels Silvia Mironeasa 1 & Mădălina Iuga 1 & Dumitru Zaharia 2 & Costel Mironeasa 3 Received: 10 August 2018 /Accepted: 25 October 2018 /Published online: 9 November 2018 # Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract The present study was undertaken to assess the effects generated by grape peels flour (GPF), as a source of dietary fibers, on the white wheat flour (WF) dough rheological behavior. Dynamic and empirical rheological measurements were carried out in order to study the viscoelasticity of GPF-enriched wheat flour-based dough matrices and to identify the main actions of GPF particle size (large, medium, and small) at replacement levels from 0% up to 9%. The water competition of GPF is explained by different water binding and gelling capacities, synergistic and/or antagonistic effects of GPF compounds on the major rheological properties. Power low and Burgers models were successfully fitted with the dynamic oscillatory and creep-recovery data being suitable to interpret viscoelastic behavior of dough. Composite flour dough with smaller particle size presented higher G′ and G″ values at addition level above 5% GPF, exhibiting higher viscous component with concomitantly higher peak viscosity. Creep- recovery tests for samples with small particle size at 5% addition level showed that the elasticity and the recoverable proportion was higher compared to the rest of GPF formulations and control sample. Significant correlations (p < 0.05) were found between several parameters determined by both dynamic and empirical rheological measurements which have essential roles in monitor- ing GPF-enriched wheat flour dough in a wide set of different kinds of samples. This information could be helpful to optimize the particle size and addition level of GPF that could be useful to produce GPF-enriched designed bread. Keywords Wheat flour . Grape peels . Particle size . Dough . Viscoelasticity Introduction The white wheat flour used in bread production exhibits a reduced nutritional value due to its chemical composition. The components of grain, such as bran and endosperm, are lost during the milling process when grain is converted to flour at different extraction rates. At an extraction rate of 75% or less (Dewettinck et al. 2008), the white flour is generated. Thus, refined wheat flour contains less fibers, vitamins, minerals, and phytochemicals than whole grain wheat flour (Vignola et al. 2016; Levrat-Verny et al. 1999). For example, the fiber content is reduced at 2.8% on a dry matter basis in white flour of 66% extraction rate compared with the whole meal flour which contains high amount of fiber (12.1% of dry matter) (Pederson et al. 1989). The absence of nutrients like dietary fiber intakes has negative physiological effects on human health. Numerous scientif- ic researches have highlighted the beneficial role of dietary fiber in the reduction of chronic diseases such as cardio- vascular disease, some forms of cancer, and constipation (Kendall et al. 2010; Rodriguez et al. 2006). Different approaches to improve the nutritional value of white wheat flour, which compensates loses due to the refin- ing, are presented in the scientific literature. One way to nu- tritionally enrich white wheat flour is through the addition of different ingredients during the bread-making process. The use of fruits and vegetable by-products has received much attention as functional ingredients for bread-making applica- tions. Some fruit by-products, as non-conventional dietary fiber source, exhibited a greater potential to improve the nu- tritional content of bakery products (Bakare et al. 2016; O'Shea et al. 2012). * Silvia Mironeasa silviam@fia.usv.ro; silvia_2007_miro@yahoo.com 1 Faculty of Food Engineering, Stefan cel Mare University, Suceava, Romania 2 Dizing SRL, Brusturi, Neamţ, Romania 3 Faculty of Mechanical Engineering, Mechatronic and Management, Ştefan cel Mare University, Suceava, Romania Food and Bioprocess Technology (2019) 12:228–245 https://doi.org/10.1007/s11947-018-2202-6