Biomedical Engineering Reference
In-Depth Information
for use of sourdough as a leavening agent. Equipment for industrial sourdough
fermentation is typically designed to carry out (semi-)automated batch fermenta-
tions according to the fermentation scheme of traditional procedures, and is thus
incompatible with large-scale and continuous bread production [
28
] . Consequently,
sourdough fermentation is increasingly carried out by specialized suppliers to the
baking industry [
29
] . The use of sourdough in bakeries employs stabilized, usually
dried, preparations that are shelf stable. This second line of sourdough products in
addition to traditional fermentations allows for product innovation to match the spe-
cialized need of individual customers. Examples include ready-to-use, active sponge
doughs, dried sourdough products enriched with exopolysaccharides or flavour
compounds derived from the Maillard reaction, and starter cultures selected for
specific metabolic traits for improved bread quality.
It is noteworthy that lyophilized starter cultures for direct inoculation of bread
dough have not found widespread commercial use in baking applications, in con-
trast to the predominant use of starter cultures in meat and dairy fermentations.
Freeze-dried cultures fail to develop the required metabolic activity in straight
dough processes, and thus require revitalization in a pre-ferment or sponge dough
prior to use. In-house propagation of sourdough with occasional restoration of the
desired fermentation microbiota with cereal-based freeze-dried starter preparations
is thus a preferred option for many bakeries.
The increasing use of sourdough as a baking improver also allows the inclusion
of non-conventional organisms and raw materials. Continuous propagation of sour-
dough invariably selects for fermentation microbiota consisting of lactic acid bacte-
ria and yeasts. The industrial production of baking improvers, however, can be
started with other food-grade organisms that grow in cereal substrates and maintain
dominance over one or a few stages of fermentations. Bifidobacteria [
30
] , propioni-
bacteria [
31
], fungi and acetic acid bacteria [
32
] all grow in cereal substrates and
have been employed in experimental cereal fermentations. Moreover, traditional
cereal fermentations employed in Africa, Asia, and Latin America for production of
steamed bread, beverages, porridges, vinegar, or condiments provide a source of
fermentation organisms that are highly adapted to cereal substrates. The metabolic
potential of these organisms vastly differs from sourdough lactic acid bacteria and
their use allows novel functionalities for baked products.
References
1. Vogel RF, Knorr R, Müller MRA, Steudel U, Gänzle MG, Ehrmann MA (1999) Non-dairy
lactic fermentations: the cereal world. Antonie van Leeuwenhoek 76:403-411
2. Meroth CB, Walter J, Hertel C, Brandt MJ, Hammes WP (2003) Monitoring the bacterial
population dynamics in sourdough fermentation processes by using PCR- denaturing gradient
gel electrophoresis. Appl Environ Microbiol 69:475-482
3. De Vuyst L, Neysens P (2005) The sourdough microflora: biodiversity and metabolic interac-
tions. Trends Food Sci Technol 16:43-56
4. Minervini F, Lattanzi A, De Angelis M, Di Cagno R, Gobbetti M (2012) Artisan bakery or
laboratory propagated sourdoughs: influence on the diversity of lactic acid bacterium and yeast
microbiotas. Appl Environ Microbiol. doi
:
10.1128/AEM.00572-12
