The Cake Theory
This professor of physics at Bristol University has a zeal for understanding the science behind cookery processes. In his wife gave him a cookbook after he finished his doctorate — with a PhD, logic suggests, you should be able to make an omelette. So he set about a surreally detailed analysis of the recipe for a Genoise sponge, translating it into rigorous scientific vocabulary.
It attracted attention in his department, not least for the success that older colleagues had in baking their own sponges with his recipe at home. But Barham was not the first physicist to become interested in food science. There were so many possibilities for ingenuity and discovery in the medium of food.
Kurti had proved it in the lecture theatre, injecting mince pies with rum through a hypodermic syringe, and tenderising a loin of pork by injecting it with fresh pineapple juice, which contains the proteolytic enzyme bromelin. The influence of this culinary scientific principle today is everywhere — in restaurants, cookery books, and on television. The dynamic began to shift in the early s, when a cookery teacher, Elizabeth Thomas, based in San Francisco, had an idea to bring scientists and chefs together.
Kurti died in Barham affirmed that the salt made no difference, and the pair began to collaborate: Today, Barham is not so much polymath as several people at once: He is also besotted with the African penguin — he has just led the 8th International Penguin Conference in Bristol — and devotes much of his research to these birds. The pressing culinary question for him now relates to the psychology of taste and flavour: This is what he and colleagues in Copenhagen want to know.
Or I might make an egg and bacon tortilla, or ice cream.
But to define complexity is very difficult; all you can do is say one thing is more complex than another. The most important phenomenon, he argues, is that increasing complexity correlates with enjoyment only up to a point.
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But give them a Valrhona, and they might eat 20g or 30g. By altering the quality of food, can you alter the quantity people are consuming, without them even noticing? This can be done either by hand if you are feeling strong, otherwise use an electric whisk.
About Cake Theory
Much of the tender, melt-in-the-mouth texture of cake comes from gas bubbles, which subdivide the batter into fragile sheets. The majority of this air is added in this initial stage by vigorous mixing of the fat and sugar — a process called "creaming". Air is carried along on the rough surfaces of the sugar crystals. This is why we use caster sugar, as the smaller the crystals, the more air is incorporated. These bubbles of air are encased by a film of fat, creating a foam. Creaming can be hard work. In Miss Leslie an American author of popular cookbooks described a technique that would allow cooks to beat eggs "for an hour without fatigue" but then advised: Have this done by a manservant.
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Take a break from beating and collect some of the mixture on your finger to taste. Notice how the smooth buttery flavour hits your mouth first, and then the sweetness comes in as the gritty sugar dissolves in your saliva. Notice that the mixture is lighter and softer than butter on its own: Also notice how the fat coats the inside of your mouth.
It is this coating ability that allows the fat to play another crucial role, that of a "shortener". The fat coats the starch and protein of the flour with an oily film, and in so doing reduces the formation of tough bready gluten. Fruit purees can also take on this role.
This leads to a cake that has a tender and "short" crumb. In factory cake-making, creating a fat that is plastic enough to spread over a large surface area of flour grains but soft enough to form globules requires the application of much science. Companies spend a lot of time mixing blends of various vegetable oils to get the perfect properties.
At home, however, the third role of fat for me takes precedence: That's why I use butter. Although the fluidity isn't carefully controlled it always makes great cakes, and has done for hundreds of years. As a child, the overriding characteristic of cakes was the sweetness of refined sugar. However, the role of sugar in cake is much more complex. Initially it carries air bubbles into the mixture. It has a tenderising effect, as it softens flour proteins.
It also lowers the caramelisation point of the batter, allowing the cake crust to colour at a lower temperature. Finally, it helps to keep the cake moist and edible for several days after baking. Salt is another vital ingredient as it acts both as a taste enhancer and to strengthen the gluten network.
Beat the eggs into the mixture and then gently fold in the flour, preferably with a metal spoon. Beaten egg is added to the mixture to stop the fat-coated air bubbles, created by creaming, from collapsing when heated. The egg proteins conveniently form a layer around each air bubble. As the temperature of the cake rises in the heat of the oven this layer coagulates to form a rigid wall around each bubble, preventing it from bursting and ruining the cake's texture. The eggs also provide the majority of the liquid water for the cake mixture. You will know the water provided by the eggs is sufficient — it usually is — if the mixture forms a thin coat on the back of a metal spoon.
If it doesn't, add a little water or milk to loosen up the mixture. Tasting is vital at every step of cake making, and I love tasting this stage, despite the raw eggs. For me the very buttery, sugary taste is the taste of childhood — the treat of cleaning the bowl out with a spoon. It you concentrate you can taste the eggs and flour as gentle background flavours.
The flour gives the mixture a slightly pasty texture, which makes it stick to the inside of your mouth.
Cake theory - Wikipedia
It was during the 17th century that eggs became the dominant ingredient for raising cakes, gradually replacing yeast. This was before chemical raising agents, so all of the air in the cake had to be added by vigorous beating. One early recipe states that four eggs should be "beaten together for two hours" to lighten a fine biscuit bread. This all changed with the discovery of chemical leavening agents such as those in self-raising flour.
The chemical leavening agent is essentially baking powder: Adding water and heat to this mixture allows the acid to react with the alkali to produce carbon dioxide gas. This is trapped in the tiny air pockets of the batter that were made when you creamed the fat and sugar. This means you don't have to add as much air in your mixing because the chemical leavening agent will do some of the work for you.
In fact, the quality of modern leaveners and other ingredients and equipment like the electric whisk means that mixing all the ingredients together all at once can still produce a light cake. However, I think the traditional method of beating the butter and sugar first is the most satisfying.
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Flour takes the role of structure-builder within the cake. The starch in the flour is a reinforcing agent that stiffens and helps strengthen the egg foam. Some of the proteins in the flour join together to create an extensive network of coiled proteins, known as gluten. It is this gluten that holds the cake together. Its elastic nature allows the batter to expand during baking to incorporate gases and then it coagulates into a strong network that supports the heavy weight of sugar and shortening.
The gentle folding action used to incorporate the flour avoids breaking the bubbles you have worked so hard to put into the mixture. It also reduces gluten formation because although this is vital to the structure of the cake, excessive beating creates too much gluten, resulting in a cake with a heavy, bready texture. Modern cake flour is made from "soft" wheats with a low protein content, as opposed to bread flour which is "hard" with a high protein content.
I always use my little finger to scrape the excess mixture from the spoon into the tins. My mother used to say that the little finger is the cleanest.