Sourdough in gluten-free bread-making: An ancient technology to solve a novel issue? Alice V. Moroni a, b , Fabio Dal Bello a, b , Elke K. Arendt a, * a Department of Food Science, Food Technology and Nutrition, National University of Ireland, Cork, Ireland b National Food Biotechnology Centre, National University of Ireland, Cork, Ireland article info Article history: Received 1 May 2009 Received in revised form 19 June 2009 Accepted 6 July 2009 Available online 26 July 2009 Keywords: Gluten-free bread Sourdough abstract The increasing demand for high quality gluten-free (GF) bread, clean labels and natural products is raising the need for new approaches in GF bread-making. Sourdough is the foremost fermentation used for baking purposes and it has been proven to be ideal for improving the texture, palatability, aroma, shelf life and nutritional value of wheat and rye breads. These characteristic features derive from the complex metabolic activities of the sourdough-resident lactic acid bacteria and yeasts, e.g. acidification, production of exopolysaccharides, proteolytic- amylolytic- and phytase activity, and production of antimicrobial substances. These effects have been extensively studied and well described for traditional baking, whereas little is known about the role of sourdough in GF baking. Yet, the microbiological and qualitative characterisation of local GF fermented products indicate an overlap with the microbiota of wheat/rye fermentation and suggest that the positive metabolic activities of the sourdough microbiota are still retained during fermentation of GF crops. Thus, the use of sourdough in GF baking may be the new frontier for improving the quality, safety and acceptability of GF bread. Ó 2009 Elsevier Ltd. All rights reserved. 1. Celiac disease and the sensory quality of gluten-free bread Celiac disease is an immune-mediated enteropathy triggered by the ingestion of gluten in genetically susceptible individuals, and it affects about 1% of the world population (Catassi and Fasano, 2008). Currently, a lifelong exclusion of gluten from the diet is the cornerstone treatment for celiac disease and only gluten-free (GF) products can be consumed by celiac. GF foods are dietary foods either consisting of ingredients which do not contain wheat, kamut, spelt, rye, barley, oats, or made of ingredients from such cereals, which must have been specially processed to remove gluten. Overall, the gluten level in GF products does not exceed 20 mg/kg in total (Deutsch, 2009). Yet, gluten-containing products, such as bread and pasta, represent a dietary staple for a large portion of the world population. Thus, the development of GF products suitable for celiac patients represents a compelling, but also very demanding call for food technologists. In particular, some commercially available GF breads are characterised by low quality, exhibiting poor crumb and crust characteristics as well as poor mouth feel and flavour (Gallagher et al., 2004, 2003a). Being mainly based on starch, these products have very low contents of various nutrients and undergo fast staling (Ahlborn et al., 2005). In most cases, commercially available GF products are not fortified (Niewinski, 2008) and contain lower levels of some B vitamins, iron, folate and dietary fibre when compared to their gluten-containing counterparts (Thompson, 2000; Yazynina et al., 2008). Since clinical evidences indicate that malabsorption of several important nutrients is associated with celiac disease (Feighery, 1999; Robins et al., 2008; Sabry and Okada, 1992), the rigorous consumption of commercially available GF products may yet worsen the already unbalanced diet of celiac patients (Mariani et al., 1999). Over the last 20 years, cereal technologists have tried to over- come these issues and to produce GF bread that could meet the expectations of celiac consumers. Various additives and combina- tions of different nutritive ingredients have been investigated and are currently used in GF bread formulations in order to improve both technological and nutritional quality of the bread. The incor- poration of nutrient-dense whole grains, such as amaranth, buck- wheat, millet, quinoa, brown rice, sorghum and teff, in GF bread formulations has recently shown the potential of increasing the nutritional value of these products, especially in terms of fibre, protein and mineral contents (Alvarez-Jubete et al., 2009; Moore et al., 2004; Pagano, 2006; Repo-Carrasco-Valencia et al., 2009; Yazynina et al., 2008). Iron fortified amaranth-based bread with satisfactory sensory characteristics was also recently produced by * Corresponding author at: Department of Food and Nutritional Sciences, University College Cork, Western Road, Cork, Ireland. Tel.: þ353 21 4902064; fax: þ353 21 4270213. E-mail address: e.arendt@ucc.ie (E.K. Arendt). Contents lists available at ScienceDirect Food Microbiology journal homepage: www.elsevier.com/locate/fm 0740-0020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.fm.2009.07.001 Food Microbiology 26 (2009) 676–684