Biomedical Engineering Reference
In-Depth Information
yeast in San Francisco sourdoughs is not brewer's yeast but
Kazachstania exigua
(formerly
Saccharomyces exiguus
), which is tolerant to more acidic environments.
Lactobacillus sanfranciscensis
(formerly
Lactobacillus brevis
subsp.
lindneri
and
sanfrancisco
) was first described as a new species in San Francisco sourdough [
7
] .
The use of sourdough during the Klondike gold rush in 1898 resulted in the use of
“sourdough” to designate inhabitants of Alaska and the Yukon Territories and is
even in use today. The Yukon definition of sourdough is “someone who has seen the
Yukon River freeze and thaw”, i.e. a long-term resident of the area.
From antiquity to most recent times, the mystery of leavening has also been
unveiled from a scientific point of view. The definitive explanation of microbial
leavening was given in 1857 by Louis Pasteur. The scientific research also verified
an assumption that the Greeks had already advanced: sourdough bread has greater
nutritional value. Pliny the elder wrote that it gave strength to the body. The history
and social significance of the use of sourdough is further described below for coun-
tries such as France, Italy and Germany where this traditional biotechnology is
widely used, and where its use is well documented.
1.2
History and Social Aspects of Sourdough in France
The history of sourdough usage in France was linked to socio-cultural and socio-
economic factors. There is little information about sourdough usage and bakery
industries (it seems to be more appropriated than baking), in general, in France
before the eighteenth century. It seems as if sourdough bread was introduced in
Gaul by the Greeks living in Marseille in the fourth century B.C. In 200 B.C., the
Gauls removed water from the bread recipe and replaced it with
cervoise
, a drink
based on fermented cereal comparable to beer. They noticed that the cloudier the
cervoise
, the more the dough leavened. Thus, they started to use the foam of
cervoise
to leaven the bread dough. The bread obtained was particularly light.
During the Middle Ages (400-1400 A.D.), bread making did not progress much
and remained a family activity. In the cities, the profession of the baker appeared.
The history of bread making in France was mainly linked to Parisian bakers because
of the geographic localization of Paris. The regions with the biggest wheat production
were near Paris, and Paris had major importance in terms of inhabitants. In that
period, the production of bread was exclusively carried out using sourdough
fermentation, the only method known at that time. Furthermore, the use of sour-
dough, thanks to its acidity, permitted baking without salt, an expensive and taxed
(
Gabelle
) raw material, and allowed one to produce breads appropriate for eating
habits in the Middle Ages [
8
] .
The seventeenth century marked a turning point in the history of French bakery.
Until then, sourdough was used alone to ensure fermentation of the dough even if in
some French regions wine, vinegar or rennet was added. Toward 1600 A.D., French
bakers rediscovered the use of brewer's yeast for bread making. The yeast came
from Picardie and Flanders in winter and from Paris breweries in summer. The breads
