Sour dough

Lactic Acid B cteri. The lactic acid bacteria are ubiquitous in nature from plant surfaces to gastrointestinal tracts of many animals. These gram-positive facultative anaerobes convert carbohydrates (qv) to lactic acid and are used extensively in the food industry, for example, for the production of yogurt, cheese, sour dough bread, etc. The sour aromatic flavor imparted upon fermentation appears to be a desirable food trait. In addition, certain species produce a variety of antibiotics. 

Sour dough bread is made all over the world in both primitive and advanced societies. In primitive societies there is no alternative, but in advanced societies sour dough bread is made for its special flavour. Sour... 

Sour dough bread has a range of flavours that are not present in other bread also it keeps relatively well. The keeping properties, no doubt, originate from some of the products of the side-reactions that have taken place in the dough. There is no need to add propionic acid as a mould inhibitor as some is likely to be present naturally. Quite possibly, some of the substances produced by the fermentation would not be permitted as additives ... 

Mixing. Sufficient flour, water and possibly salt are mixed with a starter of old dough to produce a new dough. Commercial starters for sour dough are available. 

Types of Rye Bread. The usual descriptions are logical. Rye bread is bread made solely from rye flour, rye/wheat bread contains a minimum of 50% of rye flour while wheat/rye bread contains not less than 50% wheat flour with not less than 10% of rye flour. Some recipes for San Francisco sour dough bread have a proportion of rye flour. No doubt, originally, the prospectors used what ever was available. 

Rye Proteins. While rye is the only European cereal able to completely replace wheat in bread, rye protein is not as effective as wheat protein. One reason for this is that as much as 80% of the protein in a rye sour dough is soluble compared with 10% of soluble protein in a wheat dough. One factor that inhibits the formation of a gluten-like complex is the 4-7% of pentosans present, which bind water and raise the viscosity of the dough. The crumb structure is then formed from the pentosans in combination with the starch. 

While it is always possible to make a sour dough by leaving some flour and water to acquire suitable micro-organisms a working sour dough bakery would keep its own culture going by holding back a portion of the culture. 

If the culture is to provide both the yeast and the flavour of sour dough then either it must acquire a wild yeast or a starter culture that includes yeast must be added. In some cases the sour dough culture is only used to give the sour dough taste while conventional yeast is added. 

Some sour dough bread is made by using commercial yeast but with a proportion of genuine sour dough. Ordinary baker s yeast is at a disadvantage in rye sour dough because the low pH that is essential for rye bread is not the optimum pH for the yeast. 

Triticale flour has been extensively tested in Poland, a country where rye bread is traditional. The best results were obtained by using 90% triticale flour with 10% rye flour. The rye flour was made into a flour brew for 24 hours at 28-29°C. Half the triticale flour was made into a sour dough for 3 hours at 32°C followed by mixing with the rest of the ingredients plus 1.5% of salt on the flour weight. The bread was then scaled and proved for 30 min at 32°C followed by baking at 235-245°C. 

Ingredients. A simple recipe consists of wholemeal flour, salt, water and sour dough starter. The flour would be stone ground, possibly by hand. 

Traditional pitta bread is made by a sour dough process but it can be made using manufactured yeast. If the sour dough process is used a relatively large portion of sour dough (approximately 20%) is used, giving a more rapid fermentation than most sour dough products. 

There is a view that muffins originated in Wales. They were originally a sour dough flat bread. They seem to have disappeared from British life, except in a nursery rhyme. Presumably the original product had a short shelf life. The sort of product now sold as an English muffin has overcome some of these problems. The modem product is a disc shaped product about 7-10 cm in diameter and 2 cm high. 

Rye is grown mainly in the northeastern countries of Europe and in some locations in North America and Argentina.1 Rye is used mainly for human consumption and is the principal flour used in sour dough breads and in crisp bread. 

Food Sour dough, soy sauce, yogurt, kefir, cheese, pickles, salami, anchovy, sauerkraut, vinegar, beer, wine, cocoa, coffee, tea Conservation of perishable food by the formation of lactic acid and ethanol... 

For other product classes, it is characteristic that the flavour only forms or is changed significantly during production. Thermal, enzymatic and microbiological processes can be responsible for these changes. Examples are the ripening of salami and sour dough fermentation. In both cases, undesired bacteria can cause off-flavour formation. 

The latter plays an important role with freeze-dried sour dough. The microorganisms cultivated on flour substrate already form a number of flavour constituents, which stick well to the flour matrix. The subsequent freeze drying preserves both, flavour and microorganisms. The resulting product saves time in the bakery and improves the quality of bread. 

Sour dough Wheat flour Lactobacillae, Saccharomyces cerevisiae... 

To a limited extent a starter culture once established can be propagated on site (sour dough, yoghurt cultures, yeast in the brewery). 

Bread production has become increasingly industrialised. Moreover, consumer preference has altered towards loaves of good volume, ready-sliced for convenience and which stay soft for several days. At the same time, increased demand for speciality breads e.g. French baguette type, sour doughs etc.) has increased. 

Barber, B., Ortola, C., Barber, S., and Fernandez, F. 1992. Storage of packaged white bread. III. Effects of sour dough and addition of acids on bread characteristics. Z. Lebensm. Unters. Forsch 194, 442 149. 

Collar, C., Benedito de Barber, C., and Martinez-Anaya, M.A. 1994a. Microbial sour doughs influence acidification properties and breadmaking potential of wheat dough. J. Food Sci. 59, 629-633, 674. 

Collar, C. and Martinez, C.S. 1993. Amino acid profiles of fermenting wheat sour doughs. J. Food Sci. 58, 1324-1328. 

Collar, C., Martinez-Anaya, M.A., and Benedito de Barber, C. 1994b. Interactive effects between microbial breadmaking starters and wheat flours on sour dough and bread quality. Rev. Esp. Cienc. Tecnol. Aliment. 34, 191-201. 

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