Impact of sourdough on the texture of bread
Introduction
The use of the sourdough process as a form of leavening is one of the oldest biotechnological processes in food production (Röcken and Voysey, 1995). Its main function is to leaven the dough to produce a more gaseous dough piece and as such a more aerated bread. In recent years the traditional sourdough bread production has enjoyed renewed success with the ever increasing demand by the consumer for more natural, tasty and healthy foods (Brummer and Lorenz, 1991). Early dough fermentation would probably have relied on a mixture of natural yeasts and lactic acid bacteria (LAB) (Oura et al., 1982; Williams and Pullen, 1998). The underlying functionality of such an adventitious microbial population is that dough formed by the addition of water to ground cereals will be fermented by the micro-organisms naturally present to become a sourdough characterized by acid taste, aroma and increased volume due to gas formation (Hammes and Ganzle, 1998). In addition to the yeasts naturally present on the cereal grains, brewers’ yeast was often added to enhance the fermentation process (Oura et al., 1982; Röcken and Voysey, 1995; Williams and Pullen, 1998). Variations in the process parameters including temperature, dough yield as well as the amount and composition of starter cultures determine the quality and handling properties of sourdough (Barber et al., 1992). In wheat breads, sourdough is mainly used to improve flavour (Hansen and Hansen, 1996), however the addition of sourdough also has a major effect on the dough and the final bread structure. The utilisation of baker's yeast has not eliminated the use of sourdoughs in rye breadmaking, where a reduction in pH is necessary to achieve suitability for baking (Oura et al., 1982; Hammes and Ganzle, 1998; Salovaara, 1998). There is considerable consensus with regard to the positive effects of sourdough addition for bread production, including improvements in bread volume and crumb structure (Corsetti et al., 2000; Clarke et al., 2002; Crowley et al., 2002), flavour (Thiele et al., 2002), nutritional values (see Fig. 1; Liljeberg and Björck, 1994; Liljeberg et al., 1995) and shelf-life (Corsetti et al., 1998b; Lavermicocca et al., 2000, Lavermicocca et al., 2003; Dal Bello et al., 2006).
Section snippets
Understanding the technological functionality of sourdough application
Despite its long tradition and the well-documented positive effects conferred on bread products by its use, various details about sourdough technology have not yet been fully understood. This remains the case not only with regard to sourdough microbial ecology and physiology, despite much progress in this respect (Gobbetti, 1998; Hammes and Ganzle, 1998; Brandt, 2001), but also in relation to the influence of sourdough on the structure of dough and bread. Mechanisms at work in sourdough and its
Ecology of sourdough
As the texture parameters of the finished bread are determined by the microbial acidification and rate of substrate breakdown, it is important to characterize the micro-organisms responsible for those activities. The microbial ecology of the sourdough fermentation is determined by ecological factors (Hammes and Ganzle, 1998; Vogel et al., 1996). Endogenous factors are determined by the chemical and microbial composition of the dough, whereas exogenous factors are determined mainly by
Changes in the cereal protein fraction during sourdough fermentation
From a rheological point of view it is well established that as fermentation progresses there is a change in nature of the elements contributing to dough structure such as the decrease in the viscosity described for a gluten solution (Kawamura and Yonezawa, 1982). The protein fraction of wheat and rye flours is of crucial importance for bread quality. Proteolysis provides precursor compounds for the formation of aroma volatiles during baking as well as substrates for microbial conversion of
Application of exopolysaccharides (EPS) produced by sourdough LAB
The addition of plant polysaccharides is a common practice in the production of bread to improve textural properties and shelf-life of bread. Recently, the suitability of EPS produced by sourdough LAB to replace plant polysaccharides has been investigated. Two classes of EPS from LAB can be distinguished: extracellularly synthesized homopolysaccharides (HoPS) and heteropolysaccharides (HePS) with (ir)regularly repeating units that are synthesized from intracellular sugar nucleotide precursors.
Synergistic activity of sourdough and dough additives
Further to reliance on the integral components of dough, there is an increasing trend for the use of additives in the baking industry to achieve optimum functionality in terms of dough handling properties and bread quality attributes including shelf-life (Rosell et al., 2001). The interaction between sourdough and a number of additives such as exogenous enzymes and non-starch polysaccharides has been recently evaluated (Corsetti et al., 2000; Di Cagno et al., 2003). Corsetti et al. (2000) have
Bread texture and staling
The textural properties of a food have been described as “that group of physical characteristics that are sensed by the feeling of touch, are related to the deformation, disintegration, and flow of the food under the application of a force and are measured objectively by functions of force, time and distance” (Bourne, 1982). This is however an extremely restrictive meaning in relation to those properties that can be felt in the mouth or the hand and excludes physical characteristics such as
Rye sourdough
The introduction of baker's yeast has not eliminated the use of sourdoughs in rye breadmaking, where a reduction in pH is necessary to achieve suitability for baking (Oura et al., 1982; Hammes and Ganzle, 1998; Salovaara, 1998). The baking properties of rye and wheat flours differ in so far as rye flours contain high levels of pentosans. In rye doughs the proteins play a lesser role in the structure forming process than in wheat doughs, because the pentosans inhibit the formation of the gluten
Wheat sourdough
Whereas sourdough is an essential ingredient for ensuring baking properties of doughs containing more than 20% of rye flour, its addition to wheat doughs remains optional (Röcken, 1996). There is however a vast array of traditional products that rely on the use of sourdough fermentation in order to yield baked goods with particular characteristics. The use of LAB and yeasts in the form of sourdough is well established in Italy (Corsetti et al., 2001), Germany (Seibel and Brümmer, 1991), Spain (
Gluten-free sourdough
Coeliac disease (CD) is a chronic enteropathy caused by the intake of gluten proteins from widely prevalent food sources, such as wheat, rye, barley and possibly oats. The condition is exacerbated by the ethanol soluble storage proteins or prolamins from wheat, rye, barley and possibly oats. The ingestion of gluten induces an inflammatory response resulting in the destruction of the villous structure of the small intestine (Shan et al., 2002). CD results in malabsorption secondary to small
Conclusions
Sourdough has been used since ancient times and its ability to improve the quality and increase the shelf-life of bread has been widely described. There exist a myriad of microbial, technological and processing dimensions that must be considered in order to produce cereal products of optimum quality. Significant advances have been made in understanding the contributions made by the presence of acids, the fermentation period and the role played by cereal and bacterial enzymes in terms of
References (98)
- et al.
On the presence and activities of proteolytic enzymes in vital wheat gluten
J. Cereal Sci.
(1997) Texture, viscosity and food
- et al.
Phenotypic and molecular identification and clustering of lactic acid bacteria and yeasts from wheat (species Triticum durum and Triticum aestivum) sourdoughs of southern Italy
Int. J. Food Microbiol.
(2001) - et al.
Heteropolysaccharides from lactic acid bacteria
FEMS Microbiol. Rev.
(1999) - et al.
The sourdough microflora, biodiversity and metabolic interactions
Trends Food Sci. Technol.
(2005) - et al.
Interactions between sourdough lactic acid bacteria and exogenous enzymes, effects on the microbial kinetics of acidification and dough textural properties
Food Microbiol.
(2003) - et al.
Molecular taxonomy and genetics of sourdough lactic acid bacteria
Trends Food Sci. Technol.
(2005) - et al.
Current approaches to diagnosis and treatment of coeliac disease, an evolving spectrum
Gastroenterologia
(2001) - et al.
Dietary modulation of the human colonic microbiota, introducing the concept of prebiotics
J. Nutr.
(1995) The sourdough microflora, interactions of lactic acid bacteria and yeasts
Trends Food Sci. Technol.
(1998)
Sourdough bread production with lactobacilli and S. cerevisiae isolated from sourdoughs
Process Biochem.
Microbial ecology of cereal fermentations
Trends Food Sci. Technol.
Structure and mechanics of starch bread
J. Cereal Sci.
The relevance of exopolysaccharides to the rheological properties in milk fermented with ropy strains of lactic acid bacteria
Int. Dairy J.
Sourdough fermentation or addition of organic acids or corresponding salts to bread improves nutritional properties of starch in healthy humans
J. Nutr.
Glucansucrases: mechanism of action and structure–function relationships
FEMS Microbiol. Rev.
Influence of hydrocolloids on dough rheology and bread quality
Food Hydrocolloids
Exopolysaccharides from cereal associated lactobacilli
Trends Food Sci. Technol.
Development of gluten-free cereal products
Farm Food
Antistaling additives, flour type and sourdough process effects on functionality of wheat doughs
J. Food Sci.
Effect of loaf specific volume on rate and extent of staling in bread
J. Sci. Food Agric.
Note on the sodium dodecyl sulfate test of breadmaking quality: comparison with Pelshenke and Zeleny tests
Cereal Chem.
Microflora of the sour dough of wheat flour bread. XI. Changes during fermentation in the microflora of sour doughs prepared by a multi-stage process and of bread doughs thereof
Rev. Agroquím. Tecnol. Aliment.
Storage of packaged white bread. III. Effects of sour dough and addition of acids on bread characteristics
Z. Lebensm. Unters. Forsch.
The effect of crust on the staling of bread
Cereal Chem.
Effect of an exopolysaccharides produced by Lactobacillus sanfranciscensis LTH 1729 on dough and bread quality
European developments in wheat sourdoughs
Cereal Foods World
Flour milling
Other cereals in breadmaking
Effect of single strain and traditional mixed strain starter cultures in rheological properties of wheat dough and bread quality
Cereal Chem.
Wheat sourdough fermentation. Effect of time and acidification on fundamental rheological properties
Cereal Chem.
Microbial sourdoughs influence acidification properties and breadmaking potential of wheat dough
J. Food Sci.
Interactive effects between microbial breadmaking starters and wheat flours on sour dough and bread quality
Rev. Esp. Cienc. Tecnol. Aliment.
Sourdough lactic acid bacteria effects on bread firmness and staling
J. Food Sci.
Antimould activity of sourdough lactic acid bacteria, identification of a mixture of organic acids produced by Lactobacillus sanfrancisco CB1
Appl. Microbiol. Biotechnol.
Combined effect of sourdough lactic acid bacteria and additives on bread firmness and staling
J. Agric. Food Chem.
The effect of storage time on textural and crumb grain characteristics of sourdough wheat bread
Eur. Food Res. Technol.
In vitro study of prebiotic properties of levan-type exopolysaccharides from lactobacilli and non-digestible carbohydrates using denaturing gradient gel electrophoresis
Syst. Appl. Microbiol.
Bread staling
Cereal Chem.
VSL#3 Probiotic preparation has the capacity to hydrolyze gliadin polypeptides responsible for celiac sprue
Biochim. Biophys. Acta-Mol. Basis Dis.
Proteolysis by sourdough lactic acid bacteria. Effect on wheat flour protein fractions and gliadin peptides involved in human cereal intolerance
Appl. Environ. Microbiol.
Sourdough bread made from wheat and nontoxic flours and started with selected lactobacilli is tolerated in celiac sprue patients
Appl. Environ. Microbiol.
Staling in starch bread: the effect of gluten additions on specific loaf volume and firming rate
Starch/Stärke
Clinical presentation of coeliac disease in the pediatric population
Gastroenterologia
Fortnightly review. Coeliac disease
Br. Med. J.
Mikrobiologie des Sauerteiges
Bread staling, Molecular basis and control
Comp. Rev. Food Sci. Food Saf.
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