Hydrocolloids as baking additives: influence on water absorption and rheology of wheat doughs

LINLAUD, N.; PUPPO, M.C.; FERRERO, C.

Rosario, Argentina

Conferencia; 1 Conferencia Latinoamericana. ICC 2007. ICC Internacional Conference on Cereals and Cereal Products, Quality and Safety; 2007

International Association for Cereal Science and Technology

Gluten formation during kneading is relevant to gas retention during fermentation as well as to crumb formation after baking. The quality of gluten network may be influenced by many factors, among them, the quantity of available water and the presence of additives. An excess or lack of water during dough formation are related to deficient gluten networks. Hydrocolloids are among the additives used as dough improvers. These highly hydrophilic macromolecules, mainly carbohydrates, are employed to improve bread quality and as preserving agents. The objective of the present work was to evaluate the influence of three hydrocolloids from different sources on water absorption and rheological characteristics of doughs. Guar gum, xanthan gum and high methoxyl pectin were employed in four levels (0.25, 0.5, 1, 1.5 g/100g flour). A commercial wheat flour was used. For dough preparation two conditions were assayed: (1) providing water as indicated by the farinographic absorption value obtained for each blend of flour and hydrocolloid; (2) providing water at constant level for all blends (farinographic absorption for not additivated flour). In all cases, salt was added (2 g/100 g flour). Rheological characteristics of doughs were evaluated by different methods: a) farinographic parameters (developing time, stability and degree of softening), texture profile analysis-TPA (hardness, adhesiveness, cohesiveness and elasticity) and rheometric oscillatory measurements (linear viscoelastic range, dynamic storage modulus, G’ and dynamic loss modulus, G”). By farinographic assays, it was observed that hydrocolloid addition increased water absorption in all cases. In some cases, dough stability was increased (for example, with guar gum, in all concentrations) and in others, stability decreased (with the higher pectin concentration). For doughs prepared under condition (1), TPA showed an increase in hardness when guar gum was added but a decrease when pectin or xanthan were added. Elasticity increased when increasing xanthan or guar gum levels but this effect was not observed with pectin. In rheometric assays, higher values of G’ and G” were obtained for doughs prepared with maximum concentration of guar gum and for those with minimum concentration of pectin. For doughs prepared under condition (2), hardness and adhesiveness significantly increased when xanthan or guar gum were added but not with pectin addition; cohesiveness significantly decreased in all cases and elasticity was increased at higher levels of hydrocolloids. G’ and G” values were significantly higher than control when xanthan gum was added at maximum level. From these results, it can be concluded that hydrocolloid addition affects significantly dough water absorption depending both on the type and level of gum. Besides, hydrocolloids incorporation leads to rheological changes in doughs, the trend and degree of which are affected not only by the type and concentration of hydrocolloid but also by water availability.