Bakeries: advanced technologies ensure that quality remains constant
Global trends are posing new challenges for the bakery industry
The global trends in food and drinks pose new challenges for the food industry. This is also affecting the bakery industry, which like many other sectors is being confronted by the growing prices of
raw materials and energy. This is why the bakery
industry is also demanding innovative new technologies. As the cross-sector trade fair for food and drink technology, Anuga FoodTec, which will take place in Cologne from 10th to 13th March 2009,
offers solutions for all areas of manufacturing and
packaging within the complete food and drinks industry. Here it will be demonstrated that the individual aspects of automation, such as boilers, temperature control or refrigeration technology play
an important role in many manufacturing processes
and can be implemented across sectors. As part of Anuga FoodTec, many manufacturers of food and drink technologies will be demonstrating the flexibility of their approach to sector-specific
requirements.
In the bakery industry, for example, complex machines are used to produce dough.
Fermentation systems
Especially in non-automated bakeries, batch processes are used when preparing sourdough. In this process, dough is produced from a starter culture or a mixture of “Anstellgut” — reserved sourdough
from a previous batch — rye flour and water, and
then left for a set time for fermentation. The fermentation processes taking place during this period determine to a great extent the quality of the end-product, bread. Fluctuations in the quality of
the sourdough due to individual human actions and
the resulting errors occur frequently. With automation, especially the way it is used in large bakeries, the fermentation process should take place without human interference, insofar as this is
possible. The individual parameters for the dough
making process, such as the dosage of ingredients, temperature variations and times, and freshening are subject to automatic control. The aim is to come as close as possible to achieving reproducible
sourdough quality, as this enables the production
of large batches of baked goods of consistent quality. Individual components of the plant technology used can also be found in many other areas of food production. Here the spectrum ranges from
flowmeters and double-walled boilers, right through to
plate heat exchangers.
Temperature continuity
Especially with the possibility of temperature continuity, the automated production of sourdough really shows its strengths: Under these kind of controlled conditions, temperature-related
fluctuations in acidity and in the ratio of acetic acid to
lactic acid can be almost completely eliminated. Temperature continuity is achieved by means of the insulation which surrounds the sourdough container. The temperature of the insulation system can be
controlled through cooling or heating and can
therefore eliminate the influence of ambient temperature. The fermentation process taking place in sourdough proceeds exothermically and so also leads to a rise in temperature that speeds up
enzymatic and microbial activity. There is, however, one
disadvantage in temperature control via the container’s outer wall: The leavening gas, carbon dioxide, which is found in substantial amounts during this phase of the fermentation process, is a very
bad conductor of heat. With very large plant
volumes, temperature control, especially the cooling down after reaching the optimal maturing condition, is inefficient when only carried out via the outer wall of the container. As an alternative,
very liquid sourdoughs or pre-doughs can be passed
through a heat exchanger, which achieves fast and even cooling. Such a system only requires around an hour, depending on its dimensions, to cool 3,000 litres of pumpable sourdough from the original
temperature of 30°C, to a storage temperature of
10°C.
This technology is particularly beneficial when the sourdough is in its most active stage and multiple passes are used to cool the dough in order to halt its development sufficiently quickly.
Mixing
The intensity of the movement plays a significant role in the quality of the fully fermented sourdough. It is an undisputed fact that rye sourdoughs change during the maturing phase — they get
softer. This is caused by a breakdown of water-binding
substances, which then lose their function and release the bound water. Here there is a clear difference between stirred and non-stirred doughs. A batch of manufactured sourdough in a kneading
machine will not get as soft as a constantly stirred
dough in a fermenter. The gas-retaining capacity of a sourdough that has not been stirred is therefore higher. To avoid the negative effects of the softening, both in the batch process using a
fermenter and when using fully automated systems, the
movement of the maturing dough is now avoided, or at least limited to a minimum.
Number of stages
For bakeries who value quality, multi-pass sourdough processes are often the better option. Generally, they lead to an end-product that is milder and has a more balanced taste. They will also bring a
certain amount of yeast into the main dough,
meaning that the use of baker's yeast can be completely avoided. In addition, the amount of acidified flour, along with the well-swollen components of the flour, also lead to a longer shelf life of
the bread.
However, the processing time of the finished sourdough is shorter when using multi-stage processes than it is using the simple one-step process. When using the three-stage process, once it has
matured, the dough in the last stage can be processed
without any loss of quality within a time frame of three hours. From then on the degree of acidity rises by around 1 to 1.5 degrees of acidity every hour, meaning that further processing without
problems is only possible by reducing the proportion
in the bread recipe. Automated systems can make the completed sourdough storable by cooling it once it has reached optimal maturity, meaning it can be processed over a longer timeframe.
Control
The different parameters of multi-stage, fully automated sourdough processing can only be controlled by sophisticated control technology. In addition to complying with the recipe and the temperatures
of the ingredients, it is nonetheless also
important to be able to intervene should deviations occur. However, these days this hardly every happens manually — it is done with the help of calculated scenarios and permanent monitoring using
sensors and measuring technology. Critically placed
sensors record the master data required in order, if necessary, to restore the ideal state with the help of computer-supported control systems. The controller records and archives all relevant
parameters so that the whole process can be retraced.
Just as important for a continual production of pre-dough is a cleaning system with the maximum possible degree of automation. Here, well-known techniques such as CIP or pipe pigging systems, which,
for example, are also widely known in the beverage
industry, are used.
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