Peanut brittle may seem like the simplest holiday treat, but it requires complicated chemistry to perfect.
Nothing characterizes the holiday season like the snap of a good homemade nut brittle or the stretch of a soft caramel. Like many traditions, this is more about grandparents pulling out their candy thermometers and gathering families into the kitchen than it is about the finished toffee or hard candy. But like any successful experiment in the lab, knowing the purpose of every reagent in these candy-making reactions is the key to ensuring a good outcome.
Peanut brittle relies on sugar in its non-crystalline form, so the first step to making it is to break down the disaccharide sucrose (common table sugar) to separate it into the monosaccharides that make it up—fructose and dextrose—which requires acid, water, and heat. As the sugar dissolves in water, the hydrolysis reaction will continue as long as the sugar and acid are in a fluid state, which depends on the amount of water present and how quickly it evaporates. You can control this by watching the temperature closely. For peanut brittle, start with a quantity of water that is 20-50% of the sugar by weight, and heat the solution over high heat.
As the water converts to steam, the monosaccharides begin to saturate the solution, increasing their tendency to form crystals and precipitate, which results in a gritty brittle. To prevent this, you need to interfere with the ability of fructose to rejoin dextrose. Once the solution reaches a boil, stop stirring it, since this can create cool pockets that promote crystallization. At this stage, it helps to add agents that chemically interfere with crystallization such as other monosaccharide sugars or acids. Acids tend to make syrups more prone to browning and more hygroscopic, making them soft and sticky. For brittles, glucose is the best option. Keeping the sides of the pot clean of crystals by brushing it with water can also help avoid crystallization as these crystals may seed crystallization in the solution.
Cooking is complete when the sugar reaches a certain level of saturation, which can be measured using a refractometer. But luckily for those of us who don’t keep a refractometer at home, sugar cooked to a certain temperature will always contain the same percentage of dissolved solids, so we can simply monitor our reactions using a candy thermometer. For peanut brittle, the proper level of saturation occurs at 110oC, which is where you can quickly stir in the peanuts (or substitute sesame seeds, other nuts, or cocoa nibs). Continue cooking, stirring constantly to roast the nuts and further saturate the sugar solution until the mixture reaches 155oC.
While 155oC is actually below the temperature at which sugar caramelizes, the amino acids present in the nuts contribute significantly to the Maillard reaction—a set of chemical reactions that browns everything from roasted squash to seared ribeye steak—speeding up flavor development.
When ready, remove the brittle mixture from the heat and add butter, vanilla extract, and salt to flavor your candy. Baking soda is also very important at this stage since it reacts to the heat, creating carbon dioxide that aerates the caramel, enabling it to snap when someone bites into it rather than requiring them to gnaw at it until it breaks or pulls apart. Baking soda also raises the pH of the mixture, promoting the Maillard reaction and giving the brittle its particular color and flavor profile.
Finally, pour the mixture onto a marble slab or cookie sheet so that it will cool quickly and evenly. You can stretch it as it cools if desired, or simply break it into pieces and serve it after dinner.
FAQs
Baking soda is also very important at this stage since it reacts to the heat, creating carbon dioxide that aerates the caramel, enabling it to snap when someone bites into it rather than requiring them to gnaw at it until it breaks or pulls apart.
Can peanut brittle be too hard? ›
If your peanut brittle is too hard, it might have cooked too long and reached a temperature higher than the hard crack stage.
Why do you put water in peanut brittle? ›
Peanut Brittle Ingredients
Corn syrup: Light corn syrup prevents graininess, ensuring a perfectly creamy texture. Water: Water helps the sugar completely dissolve. Salt: A pinch of salt enhances the other flavors. If you opt for salted butter, you can skip this ingredient.
Why is my peanut brittle tacky? ›
Whether it's during the cooking, cooling, or storage process, moisture and humidity can ruin the best batch of brittle in minutes, leaving you with a soggy, sticky mess. This is why eliminating moisture anywhere you can is our top tip on how to store peanut brittle.
How long does it take for brittle to harden? ›
Carefully pour the hot mixture onto the prepared pan and use a knife or spoon to quickly (and carefully!) spread the mixture into an even layer. Allow to cool completely (at least 30 minute) before breaking apart and eating. Store the completely cooled peanut brittle in an airtight container.
Why do people put co*ke in peanuts? ›
History. The combination is believed to have developed in the South during the 1920s, as a snack for blue-collar workers that did not require them to wash their hands. It quickly became popular as a summer snack, especially in rural areas. The snack became an internet trend in 2018.
Why is my peanut brittle bitter? ›
Those other liquid sugars have impurities that will burn at the higher temperature of making caramel, leading to a bitter-tasting brittle.
What is the interfering agent in peanut brittle? ›
Examples of interfering agents include corn syrup and cream of tartar. A key step in making brittle is heating the syrup to the proper temperature.
Can parchment paper be used when making peanut brittle? ›
You will want the cookie sheet to be non-stick. Use parchment paper, a silicone baking sheet or a greased cookie sheet. Spread the peanut brittle as thin as you can. Immediately add your sea salt.
Does weather affect making peanut brittle? ›
I've learned that brittle is better when made on a cool, dry day. When I've made the candy on a warmer, humid day, it tends to be a stickier brittle. This is because the brittle takes longer to cool, and it reaches a point where it is no longer evaporating moisture into the air.
Without baking soda, the brittle will be hard and chewy.
Why isn t my peanut brittle crunchy? ›
The main reason why peanut brittle doesn't get hard and have the crunch we expect is because the sugar was not cooked long enough. The sugar needs to be cooked to what is called the hard crack stage, 300ºF.
Why does my peanut brittle have bubbles? ›
The secret is in the baking soda. As the sugar is cooking and begins turning amber in color it accumulates small amounts of acid, and that acid reacts chemically with the alkaline baking soda releasing about a zillion minuscule bubbles of CO2 that get trapped, making the sugar porous and, well… brittle.
Why did my peanut brittle crystallize? ›
When candy cools slowly on a stone slab, more crystals have a chance to form. With a higher number of micro-crystals, the sugar has more sites on which to crystallize, and so crystallization ultimately happens faster.
How to soften peanuts? ›
Thoroughly rinse the raw unshelled peanuts in water. Put the water, salt, seasoning, peanuts in a large stockpot, bring to a boil: Cover and reduce the heat just enough to maintain a low boil. Boil for 2 to 3 hours or longer (some boil their peanuts all day), until peanuts reach desired level of softness.
How to break up peanut brittle? ›
Using buttered metal spatula or 2 forks, gently spread and stretch brittle to thin layer. Allow to cool completely. Break brittle into pieces and store in airtight container.
