Science of Candy: What's Special About Fudge? | Exploratorium (2024)

What’s special about fudge?

Science of Candy: What's Special About Fudge? | Exploratorium (1) Fudge is one of the rare exceptions to the rule that sugar crystals are not desirable in candy. Tiny microcrystals in fudge are what give it its firm texture. The crystals are small enough, however, that they don’t feel grainy on your tongue, but smooth.

While you ultimately want crystals to form, it's important that they don't form too early. The key to successful, nongrainy fudge is in the cooling, not the cooking. The recipe calls for heating the ingredients to the soft-ball stage, or 234° F, then allowing it to cool undisturbed to approximately 110° F. If you stir during this cooling phase, you increase the likelihood that seed crystals will form too soon.

Science of Candy: What's Special About Fudge? | Exploratorium (2) A seed crystal is a surface that sucrose molecules (that's the sugar) can begin to attach themselves to—it could be a few sucrose molecules stuck together, a piece of dust, or even a little air bubble. Once a seed crystal forms, it grows bigger and bigger as the fudge cools. A lot of big crystals in fudge makes it grainy.

By letting the fudge cool without stirring, you avoid creating seed crystals. Stirring would help sucrose molecules "find" one another and start forming crystals. Stirring also introduces air, dust, and small dried bits from the walls of the saucepan—all potential seeds for crystal formation.

When the fudge has cooled to about 110° F, you want to start the crystallization process. You start to stir, and keep stirring, until the candy becomes thick. The more you stir, the more crystal seeds you get. But instead of getting a few huge crystals (and grainy candy), you get lots and lots of tiny crystals, which make for thick, smooth candy.

There are two other candies that deliberately employ sugar crystals. One is fondant, a wetter version of fudge that you find inside soft-center chocolates. The other is rock candy, for which a sugar solution is left for days to form enormous crystals.

Think you get it? Try making fudge or rock candy yourself!

Science of Candy: What's Special About Fudge? | Exploratorium (2024)

FAQs

Science of Candy: What's Special About Fudge? | Exploratorium? ›

Fudge is one of the rare exceptions to the rule that sugar crystals are not desirable in candy. Tiny microcrystals in fudge are what give it its firm texture. The crystals are small enough, however, that they don't feel grainy on your tongue, but smooth.

How does fudge relate to chemistry? ›

When making fudge, heat and acid work together to convert sucrose – basic white sugar – into its two components, glucose and fructose. When these sugars are present, they prevent sucrose from turning into big sugar crystals.

What is the science behind candy? ›

In general, candy is made by dissolving sugar into water to create a solution. Granulated sugar, the most common type used in candy-making, is sucrose, a disaccharide molecule made up of glucose and fructose. When you force these two molecules to break apart, a very tasty reaction occurs: caramelization.

What is the secret to good fudge? ›

Valuable tips for successful fudge
  • Don't stir during cooking. Fudge can be cooked on the stove or in the microwave. ...
  • Avoid crystallization. During cooking, sugar crystals can stick to the sides of the pan. ...
  • Let cool before beating. After being cooked, the sugar must crystallize again to create fudge. ...
  • Beat the mixture.

Why must fudge be vigorously beaten after it has cooled to a specific temperature? ›

This is done after about 15 minutes of cooling when the mixture reaches 110 to 113 degrees Fahrenheit. The goal of beating the mixture is similar to the no-stir phase: it prevents a lumpy fudge. As the fudge cools down, it solidifies and beating introduces air inside which keeps it from clumping together.

What makes fudge special? ›

Fudge is one of the rare exceptions to the rule that sugar crystals are not desirable in candy. Tiny microcrystals in fudge are what give it its firm texture. The crystals are small enough, however, that they don't feel grainy on your tongue, but smooth.

What is the principle of fudge? ›

Heating the sugar and milk mixture allows the milk to dissolve more and more sugar, and by the time the mixture is boiling, all the sugar is dissolved. The general principle is that at a particular temperature, a given solvent (in this case, milk) can dissolve only so much of a particular solute (sugar).

How to make fudge more solid? ›

there is too much leftover water in the syrup and the resulting fudge is soft. To save the fudge, put it in a saucepan with 15 to 30 ml (1 or 2 tbsp.) of 35% cream and bring to a boil, stirring until the sugar is completely melted. Then let it boil until the thermometer reaches 114 to 115 °C (237 to 239 °F).

What would cause fudge not to harden? ›

The main reason is that your Fudge has not reached the optimum temperature. If your mixture only reaches 110 or 112 degrees Celsius it will always be soft. That's why we recommend investing in a sugar thermometer. Another reason your Fudge is not setting is that the ratio of liquid to sugar is too high.

Why is my 3 ingredient fudge not setting? ›

Why won't my 3 ingredient fudge set? This often happens when the condensed milk and chocolate chip mixture isn't hot enough to start. Everything must be completely melted before it is transferred to the pan to cool.

Why do you use a wooden spoon for fudge? ›

In his book On Food and Cooking, food scientist Harold McGee writes, “A metal spoon can induce crystallization by conducting heat away from local areas of the syrup, cooling them and so leaving them supersaturated [causing crystallization].” He recommends using a wooden spoon, which doesn't conduct heat.

Why can't you make fudge when it's raining? ›

Cooking candy sugar to the proper temperature requires achieving the appropriate sugar-moisture balance. High humidity hastens the breakdown of sugar as it cools. Once the candy has cooled to the point where it can no longer evaporate moisture, it can actually begin to reabsorb moisture.

What to do with failed fudge? ›

Options for what you can do with your unset fudge:

OPTION 1) Depending on how runny it is, you can either use it as a frosting for cakes, or a sauce for ice-cream. OPTION 2) Freeze it overnight. Cut it into squares. Cover each square thickly in melted chocolate, ensuring no part of the fudge is exposed.

How is chocolate related to chemistry? ›

Immediately after harvest, the beans are piled under leaves and left to ferment for several days. Bacteria create the chemicals, called precursors, needed for the next step: roasting. The flavor you know as chocolate is formed during roasting by something chemists call the Maillard reaction.

How is food related to chemistry? ›

Chemical substances can play an important role in food production and preservation. Food additives can, for example, prolong the shelf life of foods; others, such as colours, can make food more attractive. Flavourings are used to make food tastier.

What's chocolate and how does its chemistry inspire such cravings? ›

Chocolate is the richest natural source of theobromine, but coffee and tea contain some of it too. Theobromine chemically resembles caffeine and has a similar stimulating effect on our brains. The combination of theobromine and caffeine found in chocolate is believed to create the small lift we feel after eating it.

What causes fudge to crystallize? ›

The sugars probably crystallized, a common mistake when making candy like fudge or caramel. If the melting sugar splashes onto the sides of the pan, it turns back into crystals and causes the fudge to seize up. To avoid this issue, swirl the pan instead of stirring it with a spoon.

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