Effects of freezing and frozen storage conditions on the rheological properties of different formulations of non-yeasted wheat and gluten-free bread dough Guénaelle Leray, Bonastre Oliete, Sandra Mezaize, Sylvie Chevallier, Marie de Lamballerie * GEPEA (UMR CNRS 6144), ONIRIS, BP 82225, 44322 Nantes Cedex 3, France article info Article history: Received 22 October 2009 Received in revised form 17 March 2010 Accepted 20 March 2010 Available online 27 March 2010 Keywords: Wheat dough Gluten-free dough Dietary fibres Amaranth Freezing Rheological properties abstract Empirical and fundamental rheological measurements were made on fresh and frozen dough to study the effects of freezing and frozen storage conditions. Frozen dough was stored at two different temperatures, À18 °C and À30 °C, and for 1, 7 and 28 days. Four dough formulations were tested: a standard wheat dough, a fibre-enriched wheat dough, a standard gluten-free dough and a gluten-free dough containing amaranth flour. No yeast was used in any formulation. The wheat dough is more affected by freezing and by the first days of storage whereas the gluten-free dough is more affected by a longer storage time. A storage temperature of À30 °C alters dough rheological properties more than a storage temperature of À18 °C. The addition of dietary fibres to the wheat dough increases its resistance to freezing and frozen storage. The addition of amaranth flour to gluten-free dough also increases its resistance to freezing but decreases its resistance to storage conditions. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Bread is one of the most widely consumed food products in the world. For people suffering from celiac disease or other intoler- ances to gluten consumption, gluten-free breads are now available on the market. These products have a short shelf-life, and the loss of freshness has a negative influence on product quality and con- sumer acceptance. One of the approaches to solve this problem is to improve the availability of fresh bread by freezing the dough. Although no information has been found about frozen gluten-free dough, several problems in the production of bread from frozen wheat dough have been presented. These are mostly related to damage of the protein network (Varriano-Marston et al., 1980), yeast deterioration, a reduction in the water content of the surface layer of the dough (due to sublimation) and water redistribution in the system during freezing (Bhattacharya et al., 2003; Carr and Tadini, 2003; Giannou and Tzia, 2007; Le Bail et al., 1999). If the process is optimized, bread from frozen dough can have sensory and textural properties close to those of conventional bread (Barc- enas et al., 2004). In that sense, it is important to take into account that frozen dough quality is influenced by both the formulation and the process parameters during dough making, freezing, stor- age, and thawing. In order to study dough quality, rheological tests are considered a very useful tool since they can provide much information about dough formulation, structure and processing. Many studies have considered the rheological properties of gluten dough after storage in sub-zero conditions, but most only analysed individual effects such as the storage time (Angioloni et al., 2008; Bhattacharya et al., 2003; Giannou and Tzia, 2007), the storage temperature (Jiang et al., 2008) or the freezing conditions (Havet et al., 2000). Consequently, the overall changes that dough undergoes are still unknown. In gluten-free dough, rheological studies are even more scarce, and have focused on the effect of different ingredients (Nunes et al., 2009; Pruska-Kedzior et al., 2008). No information has been found about the effect of freezing or storage at sub- zero temperatures on the rheological properties of gluten-free dough. Another present concern, for bread as well as for other foods, is nutritional improvement. For conventional bread, one of the ap- proaches to improve bread nutritional quality is the addition of dietary fibres. Indeed, these have very important potential benefits for human health, such as the prevention of cardiovascular dis- eases or a reduction in the risk of colorectal cancer. For gluten-free bread, the addition of amaranth flour is a way of enhancing its nutritional benefits. The advantage of amaranth is its relatively high protein content, with an acceptable level of essential amino acids such as lysine, tryptophan and methionine (Berghofer and Schoenlechner, 2002). The lipid content of amaranth is also inter- esting since it is characterized by a high amount of unsaturated 0260-8774/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jfoodeng.2010.03.029 * Corresponding author. Tel.: +33 251 785 465; fax: +33 251 785 467. E-mail address: marie.de-lamballerie@oniris-nantes.fr (M. de Lamballerie). Journal of Food Engineering 100 (2010) 70–76 Contents lists available at ScienceDirect Journal of Food Engineering journal homepage: www.elsevier.com/locate/jfoodeng