Effect of hydrocolloids on refrigerated par-baked gluten free bread staling

GT PEREZ; PD RIBOTTA; M DE LAMBALLERIE

Madrid, España

Congreso; ICC Cereal and Bread Congress Cereals in the 21st century: present and future; 2008

ICC

Staling is a large problem in gluten free breads because they tend to quick harden. Different additives have been used to improve the quality and to prolong shelf life of gluten free breads. The storage of part-baked bread at low temperatures and the addition of bread improvers with antistaling effects are alternatives for extending the shelf life of these products. The aim of this study was to assess the influence of carboxymethylcellulose (CMC) and Xanthan gum (X) on the staling process of full baked and refrigerated partially baked gluten free bread.  Breads were made of mixtures of 40% rice flour, 40% corn flour and 20% soy flour with or without hydrocolloid (0.5% flour base). Distilled water (150%), salt (2%), shortening (2%) and compressed yeast (3.3%) (flour basis) were also incorporated. Fermented batters were full baked (40 min) or pre baked during 25 min (part-baked bread). Part-baked breads were stored at 4°C for a week and re-baked during 15 min. Full baked (FB) and part–baked (PB) breads were stored during 3 days. Specific bread volume (SBV), crumb moisture content and bread texture at days 0, 1 and 3 were analyzed. The slope obtained from the firmness-time curves was used as an indicator of staling rate. The changes in freezable water contents and amylopectin retrogradation in bread crumb during storage were assessed by differential scanning calorimeter. Specific bread volume was lower and the crumb hardness was higher in part-baked breads compared with their respective full baked breads. Hydrocolloids addition improved the specific bread volume of full baked and part-baked bread and CMC had better performance than X. Breads with CMC showed the lowest hardness at 0, 1 and 3 days and CMC addition decreased significantly the staling rate in full baked and part-baked breads. The slope from firmness-time curves of FB-control (not-hydrocolloids,C), FB-X, FB-CMC, PB-C, PB-X and PB-CMC breads were 2.81, 1.97, 1.77, 6.91, 6.61, 3.74 (units?); respectively. Crumb moisture and freezable water content (FW) in full baked and part-baked bread crumb decreased during storage. Both hydrocolloids increased the freezable water and moisture content of full baked and part-baked crumb breads, the highest values correspond to CMC breads. The amylopectin retrogradation was noticeable at 72 h, and part-baked bread showed higher retrogradation enthalpy values than full baked breads. CMC addition decrease significantly the amylopectin retrogradation in both full baked breads (C: 0.558, X: 0.542, CMC: 0.454 J/g) and part-baked breads (C: 0.939, X: 0,893, CMC: 0,875 J/g). Part-baked breads present higher staling rate and amylopectin retrogradation than full-baked breads. However CMC addition decreases staling rate and leads to softer gluten free part-baked breads.