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Science in the kitchen: the fresher the flour, the softer the cake

So how do you like my brioche? Element5 Digital/Unsplash

From the most elaborate holiday cake to the humblest loaf of bread, one of the keys to success is the beautifully aerated structure within. Yet how many cakes and loaves have slumped despite untold care being taken in their preparation? And how many bakers have fallen into despair, not knowing why their creations never puffed to perfection? Science may have now found the answer.

A research paper published in the Journal of Texture Studies brings to light a new element in the everlasting quest for perfect cake. It’s the result of work by a team of scientists from GENIAL, a joint research unit of INRA and AgroParisTech, working in collaboration with the Mondelez company. They found that the quality of a cake is strongly linked with the age of the flour used.

The softness of a cake is synonymous with its freshness. For it to be nicely soft, the walls of its cells must be regularly perforated, with small and consistently sized air chambers. The feeling of softness of a cake is influenced by the formation and distribution of bubbles in the dough rather than the firmness of the cell walls – they’re in fact secondary.

Seven cakes to bake and compare

Cakes are traditionally made with eggs, sugar, fat and flour, plus a small portion of baking powder. As the dough is being mixed, the bubbles within are stabilised by components from the eggs and flour. Flour proteins are also active during the baking itself, giving to cake its structure – ideally as smooth and consistent as possible. During the production process of large-scale bakeries, they can add emulsifiers, substances that encourage the stable mixing of normally unblendable fluids – oil and water, in particular.

A cake that was part of the study. Journal of Texture Studies, CC BY

In our study we used two different emulsifiers and flour aged at between 1 and 9 months to produce seven cakes. We then compared the cakes’ cellular structures and their softness. Afterwards, we observed the evolution of the cakes’ texture after 6, 13 and 32 weeks.

Scientific breakthroughs often involves years of research, but chance can also play a key role. Even if the subject study cannot be compared to, say, the invention of penicillin by Dr. Alexander Fleming, our discovery of the role of flour age in the cake texture was also discovered by chance. One flour sample was used both before and after summer, yet gave strikingly different results.

We were amazed to find that the age of flour had a significant impact on the cakes’ cellular structure. Indeed, during its unintended “ageing”, flour is enriched in free fatty acids that change the way air is stabilized in the form of bubbles in the batter and their behaviour during baking process. It leads to an increase in bubble size, heterogeneity and distribution, as well as cell-wall thickness. These and other changes affect a cake’s cellular structure and thus its softness.

A cross-sectional view of one of the cakes in the study. Journal of Texture Studies, CC BY

A quest for the ultimate recipe

The emulsifying agents in a cake make its bubbles smaller and more regular, and these in turn make the cake softer. Without an emulsifier, the cake’s texture will become coarser, and with all the predicable consequences – in particular, disappointed looks on the faces of all the cake lovers at the ready.

When it comes to cake storage, it’s common sense that softness decreases over time. Nevertheless, if a cake is softer to start out with, we determined that it will remain so over time compared to those that are less so, even weeks or months later.

The result of our research highlight the fact that inside a cake, cell formation is strongly related to dough composition. In addition to using flour as fresh as possi ble, regular and rapid checking of the evolution of a cake’s structure can help produce consistently soft cakes. This is why we strongly believe that the new image-analysis technique, developed by INRA and AgroParisTech, can improve baking quality control, whether it’s in the production facilities of a multinational food giant or your family’s kitchen.

This article was originally published in French

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