Whipping Egg Whites with Sugar syrup
Cooking Knowledge, Dessert, Non Recipes

How to make candy – Part 3: Aeration

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Before I will get to the practical part of the candy-making series, I want to cover one more important aspect of candy-making: aeration. Many kinds of candy are foams. They have air incorporated into them. For example marshmallows or nougat but also some hard-boiled candies.

Why do we aerate candy? There are several reasons to do so:

  • Sugar syrup with no incorporated air is clear. Aerating the sirup makes it appear opaque. This is because the air bubbles in the syrup reflect light. It’s not just sugar syrup that turns opaque when it is aerated. All foams do. You know this from beating egg whites. Raw egg whites are clear but when you beat them the egg foam turns white.
Hard-boiled candies
These hard-boiled candies are clear: They haven’t been aerated.
  • Incorporating air can make a glassy candy like peanut brittle crunchy and biteable. You cannot bite a hard-boiled candy with no air incorporated. It is too hard. Incorporating air makes hard-boiled candy flaky and light. You can bite it with your teeth and don’t need to lick it.
  • Air increases the volume of the product. This is important for food manufacturers who try to increase the size of their candy bar without adding more of the costly ingredients. Air is a free filler ingredient.

Methods for aerating candy

Several methods can be used to aerate candy. In this post, I only want to cover techniques that are realistic for the home cook. I bet that you don’t have a professional-grade vacuum candy cooker or a candy cooker with a continuous gas-injection function at home.

Aeration by pulling

The most common technique for aerating hard-boiled candy in an artisanal setting is the pulling method. Once the hot syrup starts to cool down a little, its viscosity will increase.

As long as the syrup is in the rubbery stage, it can be stretched and folded like bread dough. With each fold, you incorporate some air into the candy mass. The more folds you do, the more air is in the candy.

Traditional candy makers usually have a hook attached to the wall which they use to pull and fold the candy dough. However, you can also pull and stretch a small amount of candy by hand without a hook. Just make sure to wear gloves if your hands are heat sensitive and to prevent sticking. In the video below you can see the pulling process without a hook.

In the next video, you can see the basic production process for aerated hard-boiled candies. After the syrup has been boiled, aromas and dyes are added. Then the dough is kneaded and aerated on the hook before the candies are formed.

Aeration by gas-activated medium

Do you know honeycomb candy? This candy is aerated by adding a gas-activated medium to the boiling syrup. The by far most common gas-activated media used in candy production are baking soda and ammonium bicarbonate (“ABC-Trieb” or “Hirschhornsalz” in German, the stuff you use to leaven German gingerbread).

If a gas-activated media comes in contact with the boiling sugar syrup it will release gas. This is because baking soda and ammonium bicarbonate decompose at temperatures above 100 °C. Water and carbon dioxide get released along with sodium carbonate (for baking soda) and ammonia (for ammonium bicarbonate). Some of the gases will remain entrapped in the syrup matrix resulting in a brittle candy with many large holes in it.

Honeycomb candy
Honeycomb candy. Picture Source: beerorkid, Imgur.

It is very important to note that aeration by pulling or gas-activated media works best for hard-boiled candy. That is because hard-boiled candy is firmer, more viscous, than soft-boiled candy. The higher the viscosity of the candy mass, the more air it can hold. For soft-boiled candy, we have to apply different methods to aerate the candy.

Aeration by whipping

Hard-boiled candy is usually too firm to be whipped. And if you whip a less viscous soft-boiled candy mass in a stand mixer, it will not be able to incorporate much air. You need to add another substance to the candy which has the ability to stabilize foam.

This is where protein-rich substances like gelatine or egg whites come into play. Egg whites can be whipped into a foam and then you can add the hot syrup to the egg white foam to produce nougat. Gelatine is used for the production of marshmallows. You can whip together the sugar syrup with a gelling agent like marshmallow roots, gummi arabica, or gelatine and it will form a stable foam.

The proteins found in egg whites and gelatine have an exceptionally good ability to stabilize foams which is why many candies are not vegan. There are vegan substitutes like the chickpea cooking water that you can find in a can of boiled chickpeas. You can take that chickpea water and whip it like egg whites. But I won’t focus on vegan candy in my series. That is typically no issue for me because I eat everything and have no issues with putting gelatine or egg whites in my food.

Whipping egg whites
Egg whites form an exceptionally airy and stable foam.

Why do some proteins, especially animal proteins, have the ability to stabilize foams? Because they form a stabilizing film around the air bubbles. Proteins migrate and accumulate at the air bubble-syrup interface to form a protective layer around the air bubbles. The air bubbles get entrapped in the continuous phase, the sugar syrup, and can’t escape.

As you might know from beating egg whites, fat-molecules inhibit proteins from stabilizing a foam network. The fat molecules compete with the proteins at the air bubble interface and try to displace them. High-fat liquids like whipping cream can be foamed because there are far more fat molecules in the cream than proteins so that whipped cream can be stabilized by the fats alone. A fat-reduced 20%-fat cream can’t be whipped because the proteins and fat molecules are in constant competition to adhere to the air-water surface layer. There is not enough fat in the cream to displace all the proteins at the air bubble interface.

Milk, however, can be whipped. If you whip whole milk, the proteins will quickly adhere to the air-water surface before the fats can displace them. But milk foam is not very stable as you might know from drinking cappuccino. As soon as the fat molecules begin to displace the proteins at the air bubble surface the foam will start to collapse.

Cup of cappuccino with egg foam
The foam formed by milk proteins is less stable than the foam formed by egg proteins. However, skim milk protein foam can also be used for candy production.

Fat-stabilized foams are untypical for candies. The syrup is not drizzled in whipped cream because whipped cream contains a lot of water and can hold less air than whipped egg whites. Whipped candies are typically fat-free. If fat is added, then it needs to be added very carefully and in low amounts after foaming. But always remember that fat destabilizes protein foams. Thus marshmallows and alike are fat-free candies.

What’s next?

There is one more big theoretical topic left that needs to be discussed regarding candy production: tempering and dealing with chocolate. But tempering chocolate won’t be the next blog post in my candy-making series. Instead, I want to post some recipes before returning to the theory.

Candy bars are often chocolate-coated which is why I will discuss how to handle chocolate in another post.

If you’ve read my last posts, you are now familiar with all the basic knowledge needed to produce almost any kind of chocolate-free confectionary product. Recipes might differ but you will quickly find out that they are all following the same principles. If you’ve understood these principles, you can manipulate the candy-making process to come up with your own recipes for confectionery products.

You can save yourself a lot of trouble in the recipe-developing process if you answer yourself a few simple questions:

  • What is the texture of the candy supposed to be like? Where do I want to end up on the sucrose-water phase diagram?
  • Do I want my candy to have a short-bite? Or do I want it to be chewy? You can control that through the water, air, and doctoring agent content as well as the cooling speed of your candy recipe.
  • Do I want to end up with a transparent (like gummy bears) or with an opaque candy (like marshmallows)?

Whoever has the knowledge doesn’t have to rely on blind experimentation. A systematic approach to recipe development can save you time and a lot of frustration.

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