Sourdough is a dough containing a culture of lactic bacteria together with a symbiotic combination of natural yeasts. Sourdough is the most ancient form of bread leavening. The earliest records of bread leavened by sourdough starter cultures go back as far as the ancient egyptians around 1800 BC. The ancient Greeks recorded numerous recipes of how to make sourdough leavened bread, and north of the Alps, excavations in Switzerland show that people at the end of the bronze age (5.500 year ago), knew how to make a sourdough bread.
Reference: Handbuch Sauerteig by Spicher and Stephan, published by Behrs, 1993
Sourdough bread is characterised by a distinctively tangy or sour taste, caused by the lactic and acetic acid produced by the lactobacilli bacteria. The actual medium, known as "starter" or levain, is essentially an ancestral form of pre-ferment. It was probably discovered by accident, when some leftover gruel started fermenting and turning sour, but got cooked anyway. The result was leavened bread!
Sourdough bread is made by using a small amount (20-25 percent) of starter dough (sometimes known as the "mother dough"), which contains the culture, and mixing it with new flour and water. Part of this resulting dough is then saved to use as the starter for the next batch. As long as the starter dough is fed flour and water regularly, the sourdough mixture live on indefinitely and remain healthy and usable. It is not uncommon for a baker's starter dough to have years of history, from many hundreds of previous batches. As a result, each bakery's sourdough has a distinct taste. The combination of starter, culture and air temperature, humidity, and elevation also makes each batch of sourdough different.
Sourdough and health
In English-speaking countries, where wheat-based breads predominate, sourdough is no longer the standard method for bread leavening. It was gradually replaced, first by the use of barm from beermaking, then, after the confirmation of the germ theory by Louis Pasteur, by cultured yeasts, allowing much faster turn-around times of bread. At first this was a seemingly innocuous cost-cutting decision, but it would prove to have an incredible impact on peoples health and is one possible explanation for the high incidences of gluten- and wheat-allergies in New Zealand.
In commercial factory style bakeries the bread leavening time is dramatically shortened by adding large amounts of quick-rise bakers yeast, to reduce the turn-around time of the bread. This often results in bread being made in under two hours from start to finish. Yeast, or Saccharomyces cerevisiae (the scientific name for the yeast used in most baking and brewing), on its own is however not able to break down complex carbohydrates, gluten, and other natural flour components like phytic acid. Only during the slow, cold fermentation can the combination of wild yeasts and lactic bacteria in sourdough reduce the amounts of these components, while producing carbon-dioxide gas, which leavens the bread.
Commercial, soft bread contains large amounts of undigested wheat-gluten, a protein which reacts with the tiny villi, the intestinal linings that absorb nutrients from food. The effects of gluten on villi have been described as akin to sandpaper on wood. Animal experiments have shown that the intestinal absorption villi are long and slender before they come in repeated contact with wheat protein. Afterwards, they become blunt and broad, with a much-reduced ability to absorb. This greatly contributes to the widespread incidence of people with malabsorption, nutrient defficiencies, digestive problems and wheat allergies. In such people, not only are the absorption villi blunted, the irritation caused by the effects of gluten, produces a protective mucus over the intestinal wall and this makes it still more difficult for nutrients to pass through the intestinal wall.
Since bread is an important part of daily food consumption in western countries, it follows that it should be healthy and wholesome. Todays milling, refining, bleaching, enriching, and addition of various chemical additives to flour and baked breads (check out the list of additives, enhancers, and E's on commercial bread some time!) makes the nutritional qualitiy of these breads questionable.
At Paris-Berlin we only use certified organic flours and organic seeds, fruits, and nuts in our breads. No additives, preservatives, or artificial enhancers are used in our baking. This makes our breads truly healthy and good for you.