ORIGINAL PAPER A Study on Staling Characteristics of Gluten-Free Breads Prepared with Chestnut and Rice Flours Ilkem Demirkesen & Osvaldo H. Campanella & Gulum Sumnu & Serpil Sahin & Bruce R. Hamaker Received: 19 November 2012 / Accepted: 19 March 2013 # Springer Science+Business Media New York 2013 Abstract The effects of chestnut flour and a xanthan–guar gum blend–DATEM mixture on staling of gluten-free rice breads baked in conventional and infrared–microwave com- bination ovens were studied. Staling properties of the bread were assessed using mechanical compression (TA), differ- ential scanning calorimetry, X-ray diffraction, and fourier transform infrared spectroscopy (FT-IR). Hardness, mois- ture loss, and retrogradation enthalpy values for all bread samples increased significantly during storage. FT-IR spec- tra showed that the integrated area of peaks around 1,041 and 1,150 cm -1 wave lengths, which are related to the structure of starch retrogradation, increased with storage time. The X-ray diffractograms of aged breads indicated a B-type structure with the appearance of peaks at around 17°, 19.5°, and 22°. An additional peak at 24° was observed in breads stored for longer periods. Higher values of hardness and lower moisture contents were obtained for breads baked in an infrared–microwave combination oven, but the use of infrared–microwave combination oven did not result in ex- cessive hardness after storage. Retrogradation enthalpies and total crystallinity values of breads did not show signif- icant differences with baking type.The replacement of rice flour with chestnut flour and addition of xanthan–guar gum blend–DATEM mixture in formulations significantly de- layed staling of gluten-free breads by decreasing moisture loss, hardness, retrogradation enthalpy, and total mass crystallinity. Keywords Gluten-free . Gum . Staling . Infrared-microwave combination heating . FT-IR . X-ray Introduction Staling is a complex process that encompasses many of the physical, chemical, and sensory changes occurring in bakery products during storage, which cause large economic losses and decreases in consumer acceptance. Dough formulations include various components each undergoing complicated changes during the breadmaking process as well as during storage of bread, which make staling an extremely complex phenomenon to describe (Gray and BeMiller 2003). Starch retrogradation/crystallization, moisture diffusion, and redis- tribution among the protein–starch components and crumb– crust fractions of the bread as well as reorganization of starch polymers within the amorphous region have been related to bread staling (Ozkoc et al. 2009). These complex phenomena result in firming of the crumb, which is consid- ered as the main indication of the staling. Since firming of the crumb is caused by starch crystallization and moisture transfer from the bread crumb, most of the studies on bread staling have focused on the retrogradation behavior of the starch fraction, predominantly amylopectin (Pateras 2007). Among the components of bread dough, gluten forms a viscoelastic network that is responsible for slowing down the movement of water and retaining gas produced from I. Demirkesen : G. Sumnu (*) : S. Sahin Department of Food Engineering, Middle East Technical University, 06800, Ankara, Turkey e-mail: gulum@metu.edu.tr O. H. Campanella : B. R. Hamaker Whistler Carbohydrate Research Center, Purdue University, West Lafayette, IN 47907, USA O. H. Campanella Department of Agricultural and Biological Engineering, Purdue University, 745 Agricultural Mall Drive, West Lafayette, IN 47907, USA B. R. Hamaker Department of Food Science, Purdue University, Agricultural Mall Drive, West Lafayette, IN 47907, USA Food Bioprocess Technol DOI 10.1007/s11947-013-1099-3