Vedran Slačanac

Influence of Acidification on Dough Rheological Properties

Due to increasing consumer demands for more natural, tasty and healthy food, the traditional process of sourdough bread production has been enjoyed renewed success in recent years, (Brummer & Lorenz, 1991 ; Thiele et al., 2002 ; Lopez et al., 2003). The use of sourdoughs is a necessary prerequisite for the preparation of rye and rye-wheat combination breads (Hammes & Ganzle, 1998). The acidification process effected by the application of sourdoughs is mainly used to improve quality, taste and flavour of wheat breads (Brummer & Lorenz, 1991 ; Katina et al., 2006a ; Arendt et al., 2007), and the slow staling (Katina et al., 2006b ; Plessas et al., 2007). The addition of sourdough during production of wheat bread causes major changes in the dough characteristics (Clarke et al., 2002 ; Clarke et al., 2004 ; Ketabi et al., 2008), especially in the rheological properties of dough. The effect of the fermentation process of wheat doughs containing lactic acid bacteria are complex and depending on variations between sourdoughs. It regards on starter culture type, fermentation regime and used additives (Wehrle et al., 1997). Many of the effects of sourdough have been considered by pH value decrease which has been caused with organic acid production. Rheological properties, acidification and flavour development are the most important parameters in fermentation processes control. The rheological characteristics of dough have been changed with fermentation. Types of microorganisms, metabolic activity and time-dependent development pH value effect on rheological properties (Wehrle & Arendt, 1998). Acids strongly influence on the mixing properties of dough. Dough with lower pH require a slightly shorter mixing time and have less stability than dough with normal pH level (Hoseney, 1994). Changes in pH values caused by production of lactic acid also influence on the rheological properties of dough (Wehrle et al., 1997). Dough with containing acid has been characterized by increased phase angle and reduced complex modulus indicative of overmixing (Wehrle et al 1997). Small physical and chemical changes in the gluten network can result in significant changes in rheological properties. Clarke et al. (2002) were concluded that addition of sourdough prepared either from a single strain starter culture or a mixed strain starter culture had significant impact on the rheological properties of wheat flour dough. Koceva Komlenic et al (2010) investigated the influence of chemical and biological acidification on dough rheological properties. According to their experimental results, rheological properties strongly depend on acidification type. Dough with lower pH value showed less stability during mixing, decreased extensibility and gelatinization maximum. In general, the rheological properties of dough greatly improved when the sourdough was added.