Eggs: Just how crucial are they in baked goods?

Eggs: Just how crucial are they in baked goods?

18 August 2021 | Sarab Sahi, Rheology & Texture Section Manager

Around the world, the aroma of freshly made bread and other baked goods is irresistible to most people. The pandemic only appeared to accelerate the attraction towards these products, with demand for bread increasing 50% at one-point last year, further cementing it as one of the UK’s favourite staple foods.

The wide range of products that yield the delicious smells and tastes of freshly baked goods is the result of a complex interaction of various ingredients and physical processes. Egg is seen as a crucial component of many baked goods, due to its unique functional properties and the significant contribution it makes to structure, appearance, texture and taste.

Exquisitely simple, yet enormously complex, the egg is one of Nature’s marvels. It is a common ingredient in many products, such as cakes, pastries, meringues, macaroons, custard fillings, quiches and pancakes. But just how vital is it in baked goods? Here we’ll investigate the many functions this ingredient offers in order to address this question.

Egg’s Anatomy

Eggs consist of a clear white albumen, which comes from albus, the Latin word for ‘white’. Four alternating layers of thick and thin albumen contain approximately 40 different proteins, which are the main components of the egg white in addition to water.

The yolk contains less water and more protein than the albumen, some fat, and most of the vitamins and minerals of the egg. These include iron, vitamin A, vitamin D, phosphorus, calcium, thiamine, and riboflavin, and yolk is also a source of lecithin. Yolk colours range from just a hint of yellow to a magnificent deep orange, according to the feed and breed of the hen.

An examination of the functional properties of eggs is useful to understand how much they contribute to the baked goods we know and love today.

Binding

In cakes, muffins, cookies, pancakes, waffles, doughs and many other baked goods, whole eggs are used as a binder. Eggs are natural binders, helping hold all other baking ingredients together and increasing the viscosity of batters and doughs. Egg white has the capability to gel and is frequently used as a binding agent in many different prepared foods. Using more whites in a cake mixture will help create a fluffy, light baked product with good volume and texture; while using more yolks will create a denser baked good with a deeper, richer flavour.

Aeration/Foaming

Aeration is a critical function in the formulation of baked goods. It refers to the process of introducing gas into a liquid or viscous solution. Beaten whole eggs as well as egg whites on their own, are highly effective leavening agents, incorporating air into the dough or batter. As the air bubbles are trapped in the mixture, a foam is created, which will expand in the oven, causing cakes to rise, providing volume and a lighter texture.

Egg whites’ ability to make foods foam is due to complex interactions between the various proteins that make up egg white. The different protein components show a range of functionalities that affect both the tension between air-liquid interfaces as well as the viscosity of the liquid phase and it is this unique combination of properties that results in egg being such an effective raw material. The globulin proteins are highly surface active and they contribute to the formation of small bubbles when egg white is beaten, hence providing smooth texture to a cake or meringue. Egg whites can be whipped to produce foams that are six to eight times greater in volume. Another key protein is ovomucoid which gives egg white its viscosity and this slows the liquid draining out of foams thus making the foam more stable.

An examination of the functional properties of eggs is useful to understand how much they contribute to the baked goods we know and love today.

Structure setting properties

Egg white proteins also contribute to the setting of the structure of batter systems. The major protein of egg white ovalbumin is easily denatured by heat and helps to set and stabilise the liquid foam to a more stable solid structure in the oven. It should be pointed out that the ovalbumin changes to the more heat-stable form of S-ovalbumin during storage. What this means in practice is that a higher temperature has to be achieved in order to fully set structure. Ovotransferrin is also sensitive to heat and provides important support to the product structure.

Emulsification

Egg yolk is rich in fat and lecithin, an emulsifier, and can therefore be used as a highly effective, natural aid to emulsification. Emulsifiers provide superior palatability, mouth feel, texture and a consistent, high-quality appearance.

Emulsifiers are a crucial baking aid because they deliver process stability during the baking process, which results in volume increase and a good crumb structure. In general, emulsification stabilises the fat phase in batters, with one part of the emulsifier molecule attaching to the fat and the other to the water. By sitting at the fat-water interface, they hold the two phases together. This provides stability to the bubbles that form in the dough, helping to deliver an open, light, aerated texture.

With the help of emulsifiers, once mixed with other food ingredients, many of the fatty components of egg yolk are held in suspension, such as in batters (a non-baking example would be mayonnaise).

Flavour and colour

In products such as enriched bread and pastries (as well as non-baked goods such as pasta and noodles) whole eggs are added for flavour and colour. The eggs are added straight to the dough or roux either all at once or in batches at a time. In these examples, eggs are not the primary means of binding and their emulsification properties are a bonus, their main function being to provide good flavour and natural colour.

Whole eggs are often used as a glaze in numerous baked goods as they turn an attractive golden brown colour and shine when cooked. This is due to the Maillard reaction when the amino acids in the egg react with the reducing sugars. It is this reaction which creates the characteristic flavour and aroma of baked goods.

Eggs also add essential moisture to finished baked goods, reducing the risk of cakes and sponges which are too dry and crumbly, thus improving eating quality and overall mouth-feel.

Eggs: Just how crucial are they in baked goods? - Image 1

Substituting eggs in products can be a challenging task, yet many manufacturers are attempting it to create products suitable for vegans.

Are there any substitutes?

Substituting eggs in baking can be a challenging task. It is extremely hard to find one ingredient that can match all the beneficial properties of the egg. While there are some good egg substitutes available on the market, there is no single egg alternative that provides all the functionality and natural capabilities of the egg itself. It’s normally necessary to add more functional ingredients when using egg substitutes.

For example, for binding purposes, ingredients such as ground flaxseed or potato starch may be used but other ingredients would need to be added to provide structure building, such as soya bean or milk proteins. For emulsification, lethicin (a naturally occurring emulsifier in eggs) can be added. To introduce more colour, beta-carotene could be added but again, this adds to the list of ingredients on packaging, potentially deterring consumers seeking ‘clean label’ products.

It is important to remember that eggs are in baking recipes for specific, functional purposes. If eggs are substituted, the resulting products will not have the same taste and texture as baked goods that incorporate eggs. With that said, our team at Campden BRI do provide support to the baking sector with ingredient suitability, product formulation and processing conditions, to help businesses with their specific challenges in this area.

No two eggs are the same

Eggs are a naturally occurring product and one of the challenges of baking with eggs is that there is inevitably an element of variability when it comes to egg quality. The food industry needs consistency to meet consumer expectations for uniformity and stability. Free range eggs, while a huge positive for the food industry as a whole, represent a challenge for the baking sector.

Egg characteristics will change depending on the age of hens, their diet, production practices, genetics, egg storage and distribution, to name a few factors. Bakers must always be aware that no two eggs are the same and that different batches of eggs may result in slightly different end products.

Nature’s marvel

Eggs are one of the most important, natural ingredients in baking. Egg-free baking recipes are few and far between, and for good reason – for many products eggs are indispensable. Eggs bind, aerate, leaven, emulsify, thicken, aid in setting, are the base in many recipes and can be used as fillings, toppings, glazes and also for adding flavour and colour to baked goods. No other single ingredient can do so much in baking. Nature’s very own miracle food product, the humble egg’s ability to do so many jobs – and all at once - is the reason why bakers the world over depend on it so much.

Sarab Sahi

About Sarab Sahi

Sarab graduated in Biochemistry, and studied for a PhD at Reading University characterising the surface properties of food grade sucrose esters then subsequently as a Research Fellow.

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