The CO2 Science of Aerated Bread

The CO2 Science of Aerated Bread

Are you exhausted after a long, arduous, all expenses paid [and frivolous] trip to Paris?

Then get yourself a coffee, grab a croissant, sit down and read all about aerated bread.

In 1862 Dr. John Dauglish founded The Aerated Bread Company after perfecting a new technique for bread making using carbon dioxide [aka carbonic acid gas].

The Aerated Bread Company Ltd was founded in 1862 by Dr. John Dauglish (1824–1866).

Having been thoroughly unimpressed by the Scottish bread of the day, he began to make his own, and to study the science associated with the process.

When he applied his earlier studies in chemistry to the process of bread making, he determined that it would be possible to produce carbonic acid gas in bread without yeast.

He established that if one could instead introduce carbon dioxide to the process – by dissolving it into solution in the water – this would eliminate the need for fermentation, dramatically reduce the need for physical contact with the dough on the part of the workers, and consequently introduce a greater level of cleanliness into the bread making process.

Evening Telegraph - Philadelphia - 11March 1871

Pumping dough with carbon dioxide revolutionised the bread making industry [like the way pumping dough into the Earth Sciences revolutionised Climate Science].

The aeration method accrues to the bakery three production economies: material savings, time savings, and labour savings.

As an illustration of the first of these economies, Dauglish estimated that, by eliminating the decomposition of the starches and gluten that occur from traditional fermentation (a loss equal to between three and six percent), this had a value in the middle of the 19th century of “£5,000,000 in the total quantity of bread made, annually, in the United Kingdom” (£427,000,000 in current terms).

The process is a highly automated one, and thus saves time and reduces labour costs.

Whereas the traditional dough fermentation method required between eight and ten hours to ready a batch of dough for baking, the Dauglish method has dough ready for the ovens in approximately half an hour.

And since the bread dough is ready for the ovens so quickly, the daily hours worked can be reduced, obviating the need for the night shifts that were so prevalent in the baking industry at the time.

Finally, the lack of most additives to enhance the fermentation process reduces the cost of factor inputs while also producing a virtually unadulterated product.

The technology so reduced the cost of production, that it meant that A.B.C. could sell its product for less than its competitors, the traditional fermentation method bakers.

The downward impact on prices of A.B.C. moving into a market could be felt almost immediately.

For example, in 1866 Australia, A.B.C.’s lower prices forced other bakers to reduce theirs in turn, by between 8 percent and 17 percent.

Aerated Bread Company Depots

New York Public Library

Pumping dough with carbon dioxide also meant consumers no longer had to worry about finding dirty fingernails and filthy toenails in their bread.

Dauglish sought to abolish manual kneading, which he believed was unclean and unhealthy.

Some years later, an 1878 issue of the scientific journal, Nature, reported:

As to the perfect cleanliness of this mechanical process for making bread there can be no question; it is immeasurably superior to the barbarous and old, but as Dr. Richardson remarked, not “time-honoured system of kneading dough by the hands and feet of the workman.

Bethnal Green water supply 1863

Baking advanced in the 1960s with the Chorleywood Bread Process.

The Chorleywood bread process (CBP) is a process of making dough in bread production.

The process was developed in 1961 by the British Baking Industries Research Association based at Chorleywood, and is now used to make 80% of the UK’s bread.

Compared to the older bulk fermentation process, the CBP is able to use lower protein wheat, and produces bread in a shorter time.

But carbon dioxide is still an important factor in the Chorleywood Bread Process.

The Pressure-Vacuum mixer was later developed by the Flour Milling and Baking Research Association at Chorleywood.

With the application of both pressure and vacuum at different points in the mixing process, this mixer not only manipulates the gas bubble size, it may also manipulate the composition of gases in the dough via the gas applied to the headspace.

Water activity, CO2, and their interaction were the main factors significantly affecting fungal growth.

Water activity at levels of 0.80 to 0.90 had a significant influence on fungal growth and determined the concentration of CO2 needed to prevent cake analog spoilage.

At an aw level of 0.85, lag phases increased twofold when the level of CO2 in the headspace increased from 0 to 70%.

Modified Atmosphere Packaging for Prevention of Mold Spoilage of Bakery Products with Different pH and Water Activity Levels
M E Guynot, S Marin, V Sanchis, A J Ramos
Journal of Food Protection – Vol. 66 No 10 – 2003

Carbon dioxide is also important when bread is made traditionally using yeast.

By fermentation, the yeast species Saccharomyces cerevisiae converts carbohydrates to carbon dioxide and alcohols – for thousands of years the carbon dioxide has been used in baking and the alcohol in alcoholic beverages.

Carbon dioxide is also important in the packaging of bakery goods.

In general, no fungal growth was observed for up to 28 days of incubation at 25°C when samples were packaged with 100% CO2, regardless of the aw level.

Modified Atmosphere Packaging for Prevention of Mold Spoilage of Bakery Products with Different pH and Water Activity Levels
M E Guynot, S Marin, V Sanchis, A J Ramos
Journal of Food Protection – Vol. 66 No 10 – 2003

Carbon dioxide is also very important in the preservation of grains.

There are two methods for preserving grains with carbon dioxide.

One method is placing a block of dry ice in the bottom and filling the can with the grain.

Another method is purging the container from the bottom by gaseous carbon dioxide from a cylinder or bulk supply vessel.

Carbon dioxide prevents insects and, depending on concentration, mold and oxidation from damaging the grain.

Grain stored in this way can remain edible for approximately five years.

Nitrogen gas (N2) at concentrations of 98% or higher is also used effectively to kill insects in the grain through hypoxia.

However, carbon dioxide has an advantage in this respect, as it kills organisms through hypercarbia and hypoxia (depending on concentration), but it requires concentrations of above 35%, or so.

This makes carbon dioxide preferable for fumigation in situations where a hermetic seal cannot be maintained.

Carbon dioxide is also a very important factor when it comes to growing grains.

Photosynthesis is a process used by plants and other organisms to convert light energy, normally from the Sun, into chemical energy that can be later released to fuel the organisms’ activities.

This chemical energy is stored in carbohydrate molecules, such as sugars, which are synthesized from carbon dioxide and water

In most cases, oxygen is also released as a waste product.

Plants Need CO2

More CO2 in the air means more plant growth.

The Nongovernmental International Panel on Climate Change (NIPCC)

Climate Change Reconsidered II – Chapter 1. Carbon Dioxide, Plants and Soils

Appendix 3
Table 1.1.1 — Plant Dry Weight (Biomass) Responses to Atmospheric CO 2 Enrichment

I hope you didn’t choke on your croissant when you realised pumping dough doesn’t last forever.

Gallery | This entry was posted in Atmospheric Science, Earth, Fossil Fuels, History, Science. Bookmark the permalink.

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