Relationship between batter properties and gluten-free bread quality

SCIARINI, L; CHEVALLIER, S.; DE LAMBALLERIE, M; PÉREZ, G

Madrid, España

Congreso; 13th ICC Cereal and Bread Congress; 2008

ICC. International Association for Cereal Science and Technology (ICC)

Celiac disease is an inflammation of the small intestinal mucosa caused by the ingestion of the proteins of certain cereals such as wheat, barley, rye and some related species like triticale, in genetically susceptible individuals. At the moment, the only treatment for celiac patients consists in a lifelong gluten-free diet. Gluten is the main structure-forming protein in flour, and is responsible for the elastic characteristics of dough, while contributing to the appearance and crumb structure of many baked products (Gallagher et al., 2004). Therefore, many gluten-free breads available on the market are of low quality, exhibiting a dry crumbling crumb, poor mouth feel and flavour. Different hydrocolloids are added to these matrixes in order to mimic the viscoelastic properties of gluten in the batters. Several rheological techniques are used to evaluate the mechanical properties of doughs and batters. In the current study, batter mechanical properties and quality parameters of the gluten-free end product were recorded, and the effect of hydrocolloids addition was evaluated. Breads were made of mixtures of 40% rice flour, 40% corn flour and 20% soy flour. Tap water (150%), salt (2%), shortening (2%), compressed yeast (3.3%) and hydrocolloid (0.5%) were used. The hydrocolloids employed were xanthan gum and carboxymethylcellulose (CMC). A rheological evaluation was carried out to determine the batter mechanical properties. A frequency sweep was made using a parallel plate geometry (40 mm diameter, 2 mm gap) at a constant strain of 0.01% (determined by a previous strain sweep at a frequency of 0.1 Hz). Specific bread volume (SBV) was measured by rapeseed displacement method; crumb texture at days 0, 1 and 3 was analysed, and the slope obtained from the three points was used as an indicator of staling rate. Crust colour was measured using CIE-Lab scale. Bread loaves were scanned and a crumb image analysis was made. The addition of hydrocolloids to the batters yielded an increase of G’ values at all frequencies studied and a general decrease in tan d (G”/G’), indicating that these batters were firmer and more elastic than the control batter. These differences were higher with xanthan addition. Those breads with added hydrocolloid showed higher SBV than the control (without any hydrocolloid addition). Initial hardness was lowest for breads with CMC, followed by breads with xanthan addition with an intermediate initial hardness value and the control with the highest value (p lower than 0.05), and while higher the initial hardness, higher the staling slope. This slope was closely related to the moisture loss during storage time: breads with higher staling slope also showed a higher moisture loss. Regarding crust colour, breads showed significant differences only for the L* parameter, which is related to the sample lightness. Control breads presented lower L* values compared to breads with hydrocolloid addition. Breads with hydrocolloid showed a better crumb structure, determined by a higher cell area with a homogeneous distribution, with regard to the control. Hydrocolloid addition increased SBV improving batter development and gas retention capacity through the increase of batter viscosity and elasticity. In conclusion, those batters with higher G’ values and lower tan d showed better quality parameters (SBV, crumb structure and texture) of the gluten-free end product. Gallagher E, Gormley TR and Arendt EK.: Recent advances in the formulation of gluten-free cereal-based products. Trends in Food Science and Technology (2004) 15, 143-152.