Original article Wheat dough rheology and bread quality effected by Lactobacillus brevis preferment, dry sourdough and lactic acid addition Daliborka Koceva Komlenic´,* Z ˇ aneta Ugarcˇic´-Hardi, Marko Jukic´, Mirela Planinic´, Ana Bucic´-Kojic´ & Ivica Strelec Faculty of Food Technology, F. Kuhaca 20, HR-31000 Osijek, Croatia (Received 13 October 2009; Accepted in revised form 7 April 2010) Summary The inﬂuence of chemical and biological acidiﬁcation on dough rheological properties and bread quality has been investigated. Two diﬀerent ﬂour types were used. Dough was chemically acidiﬁed with lactic acid. Two types of biologically acidiﬁed dough were prepared: dough with dry sourdough and with a Lactobacillus brevis preferment. Wheat dough rheological properties were investigated using the Farinograph, Extens- ograph and Amylograph. The baking response was also determined using standard baking tests. Addition of acidiﬁers resulted in ﬁrmer doughs with less stability, decreased extensibility and decreased gelatinisation maximum. The biological acidiﬁers increased the bread speciﬁc volume. Lactic acid addition had no inﬂuence on bread speciﬁc volume. In general, biological and chemical acidiﬁcation decreased bread hardness. The addition of dry sourdough signiﬁcantly decreased the lightness and increased the yellowness and redness of the bread crumb. The crust chroma, hue angle and brownness index were signiﬁcantly changed by addition of acidiﬁers. Keywords Colour, dough rheology, dry sourdough, lactic acid, Lactobacillus brevis. Introduction The traditional process of sourdough bread production has enjoyed renewed success in recent years, due to increasing consumer demands for more natural, tasty and healthy foods (Bru¨mmer & 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 & Ga¨nzle, 1998). In wheat breads, the acidiﬁcation process aﬀected by the application of sourdoughs is mainly used to improve quality, taste and ﬂavour (Bru¨mmer & Lorenz, 1991; Katina et al., 2006a; Arendt et al., 2007), as well as 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 char- acteristics (Clarke et al., 2002, 2004; Ketabi et al., 2008). The eﬀects of the fermentation process of wheat doughs containing lactic acid bacteria (LAB) are complex due to variation between sourdough with regard to the starter culture type, fermentation regime and additives used (Wehrle et al., 1997). Many of the eﬀects of sourdough have been attributed to a drop in pH value caused by the production of organic acid. Lactic acid is the main metabolic product of the LAB present in sourdough. Measuring of pH levels is regarded as a satisfactory method for controlling the sourdough ripening stage. The eﬀect of application of sourdough fermentation process on dough properties is more than simple acid production (Hammes & Ga¨nzle, 1998; Thiele et al., 2002). The changes in the pH values may have a direct impact on the constituents responsible for development of dough structure such as gluten, starch and hemicel- luloses. The acids have the eﬀect on the ﬂour enzymes, thus inﬂuencing the nature and degree of proteolytic and amylolytic activity. Also, the microorganisms have the eﬀect on bread dough (Wehrle et al., 1997; Thiele et al., 2002). The production of preﬂavour substances by bacteria strains, such as free amino acids or sugars, is most important for aroma development (Collar et al., 1991; Hansen & Schieberle, 2005; Plessas et al., 2008). In addition, the advantage of sourdough is the improved shelf life of products (Armero & Collar, 1996; Gu¨ l et al., 2005; Katina et al., 2006b). Disadvantages of sourdough use are the increasing of labour input and higher production uncertainty. The invention of dried sour- dough is one attempt to overcome these problems. A major disadvantage of dried sourdough is aroma decrease (Rocken & Voysey, 1995). The rheological characteristics of doughs changed entirely with fermentation. Important parameters in *Correspondent: E-mail: daliborka.koceva@ptfos.hr International Journal of Food Science and Technology 2010, 45, 1417–1425 1417 doi:10.1111/j.1365-2621.2010.02282.x Ó 2010 The Authors. Journal compilation Ó 2010 Institute of Food Science and Technology