shortbread, caramel chocolate bars

The Science of Caramel (+ Recipe and Troubleshooting)

An almost golden brown colour, sweet, oozy or chewy, runny or firm, caramel can be found in all shapes and sizes. You can make a runny caramel sauce to poor over an ice cream, make some chewy caramel bites or swirled some into ice cream. Caramel can upgrade your creation to something even more special.

All made with just a few basic ingredients and a pretty similar preparation method. That said, caramel can be finicky, crystallizing when you don’t want it to do. Or it turns out too thick or thin. About time to dive into the science of caramel in order to help you make a perfect caramel and fix one when it all goes haywire. Caramel is super flexibly, hard to mess up completely, but it helps knowing what goes on to fix it up again.

What is caramel?

Even though there are a lot of caramel types, the basis is always sugar.* Caramel is brown, but it can vary from a light brown/orange colour to a very dark brown, closer to being black. This brown colour is formed during caramelization of the sugar. This caramelization also contributes to the flavour of caramel. Therefore, even though caramel is sweet, it has more depth of flavour. Caramel can actually be quite bitter and have a far more complex flavour profile.

Apart from sugar there are a lot of other ingredients that can be a part of caramel. The most common are milk, butter, cream, salt and water. These contribute to the richness of a caramel and the flavour profile, as we will come back to later.

*There are plenty recipes for caramel without any sugar, look-a-likes. But, since caramelization (the basis of any caramel, we’ll come back to it later) can only occur with sugars, the definition we’ll use here is that a caramel requires sugar.

How to make caramel

When making a caramel you are trying to achieve two things:

  1. Creating a nice brown colour (from uncoloured ingredients) through chemical reactions
  2. Creating the desired caramel consistency (whether it’s runny or firm)

Browning a caramel – caramelization

The nice brown colour of a caramel can be formed through the caramelization of sugar. By heating sugar to very high temperatures (regular sugar caramlizes at 160°C (320°F)) caramelization sets in. Caramelization is a series of chemical reactions in which the sugar participates. As a result of these chemical reactions larger molecules will form which have a brown colour.

Caramelization of sugar is done by heating the sugar without any other ingredients (except for water) to the correct temperature. At this temperature caramelization will set in and occur by itself, only cooling down the sugars will stop the caramelization again.

Browning a caramel – Maillard reaction

There is another way to form a brown caramel, without heating the sugar to these high temperatures. It is another very common chemical browning reaction in food: the Maillard reaction. During this reaction molecules with a brown colour are formed as well. However, instead of just sugar, this reaction also requires proteins to occur. Since butter, milk and cream contain these proteins, they can be added to sugar to initiate the Maillard reaction. Since this browning reaction will start to occur at far lower temperatures than caramelization, it is also used quite often in recipes.

Caramelizing sugar for caramel

You can caramelize sugar by heating it to temperatures well above the boiling point of water (160°C). As mentioned before, regular sugar (sucrose) will only caramelize at a temperature of 160°C. When making caramel at home there are two different ways to bring the sugar to this high temperature:

  1. The dry method: using only sugar, nothing else
  2. The wet method: using sugar and water, this one is a little more fool proof and my go to method

The dry method

In this method you place sugar in a pot and heat it gently until it starts to melt and subsequently start to brown, the caramelization. It is very important that all sugar it heated up evenly, else some might already brown, whereas other parts are still solid sugar crystals. This method tends to be more tricky than the wet method. However, it is quicker (you don’t have to evaporate all that water again) and it does give the same quality product.

The wet method

This more fool-proof method uses sugar and water. Instead of pouring the sugar in a pan by itself, you mix it with some water. The advantage is that the sugar will dissolve in the water. Since it is dissolved in the water it is easier to heat it evenly. While heating the sugar now, you’ll boil of the water. The more water that is boiled of, the warmer it becomes. Once the water has all evaporated the sugar is warm enough and caramelization will start.

It doesn’t matter how much water you add. Adding more water will result in a longer boiling time. If you don’t add enough water though, not all the sugar will dissolve. It is no problem to add extra water during boiling. It will just take more time.

caramel bars, millionaire shortbread, shortbread, caramel & chocolate

Crystallization of sugar during caramelization

Regular sugar (sucrose), is quite special. When you buy a pack of sugar all the sugar will be crystalline, they are crystals. When making a caramel you do not want these crystals. Instead, you want to create a smooth consistency and crystals don’t belong there. This is why the wet method helps you in making a smooth caramel. It helps to melt the crystals by first dissolving them. That said, with both methods it is still possible to create those unwanted sugar crystals. Fortunately, they can be cleared away again quite easily.

So how do those sugar crystals form? Sugar molecules strongly prefer to sit in this crystalline structure. They only need a little help to recrystallize again when they are dissolved or melted. The higher the concentration of sugar, the higher the chance they will form these crystals again. This is why especially close to the caramelization temperature, when with both preparation methods there’s barely any moisture left, crystallization has a higher chance to occur.

Preventing crystallization

There are a few tips and tricks to prevent crystallization of sucrose. The first is to add a crystallization inhibitor. This is an additional substance that can prevent sucrose from crystallizing. One of the most common inhibitors is glucose syrup. Glucose syrup isn’t only glucose. Instead, it also contains longer molecules. These molecules can interfer with the crystallization of the sugar, they will be in the way of the sugar molecules when trying to build a new crystal.

Sugar crystals tend to build up onto something. As soon as you have a crystal in your mixture, it will spread out very rapidly. These crystals will form more easily in a drier area (e.g. if some sugar sits on the wall of a pan where most moisture has evaporated) or on loose bits and pieces in your pan. A stirrer can also be an area where crystals start to grow. This is why most recipes will warn you to not stir the sugar while caramelizing, only do so at the start when the crystallization is not that likely to occur!

Solving crystallization in caramel

The easiest way to solve the crystallization (and the most effective) is to add more water. In other words, start over again. By adding the water, the sugar crystals can again dissolve. Simply re-heat the sugar, evaporate the water and try again!

Stopping caramelization

Once you’ve succeeded to caramelize your sugar without having any sugar crystals, you will need to stop the caramelization again! Since the sugar is super warm at this point (remember, it’s about as hot as an oven!), the reaction will continue going for a while. The caramelization won’t stop immediately, even if you turn off the heat. As a result, the caramel may become way too brown or it might even burn.

That’s why most recipes will tell you to add something to the caramel to cool it down again. It can be as simple as adding some water. Often though you will see that you have to add some milk, cream or butter. The advantage of adding these into the hot sugar is that they will also participate in chemical reactions. This will improve the flavour of your caramel even further.

Always keep in mind that the sugar is very hot at this point. It is way easiest to add something liquid, this will mix in most easily. However, take care that it will boil almost immediately and it might therefore splash. If you add something with plenty proteins (e.g. milk or cream) take care that it will bubble up a lot.

Controlling caramel consistency

Caramels can be sauces, syrups or thick gooey bites. In most recipes you will first try to get the colour of the caramel right, before you focus on the consistency itself.

When you’ve just carmelized your sugar at 160°C to the right colour, the caramel contains <1% water. If you leave this to cool down it will become a rock hard piece of caramel. It might looks fancy, but there’s no way you’d be able to eat this without breaking off some teeth. The sugar has formed a glassy structure.

You can make it softer again by adding moisture. This can be water, but also milk or cream for instance, as long as water is added. Adding a lot of moisture will result in a sauce or syrup. Adding only a little bit of water will result in a thicker less runny caramel. The good thing about sugar and water though is that these are all reversible processes. If you’ve added too much water, simply bring the mixture to the boil and wait until the consistency is correct again. If you haven’t added enough, just add some more to make it thinner.

Caramel science troubleshooting

Grainy caramel

When a caramel has become grainy, the sugar has started to crystallize. If this always happens for your recipe, you might have to add some inhibitors as we discussed in the article. Adding inclusions into the caramel, for example peanuts, makes it more prone to crystallization and thus graininess. In those cases, you might want to take some extra measures.

Separating caramel

A caramel can split if there’s fat in the caramel (e.g. from butter or cream). Often, a split caramel can be saved by gently reheating the caramel and stirring continuously. Adding some extra water can also help here to mix everything again before boiling off that extra water one more time. Last but not least, do not heat or cool down the caramel too rapidly. The fat might melt or solidify at a different rate than the caramel, causing the split.

Why caramel becomes (too) hard

No worries here! Just add some extra moisture, reheat and you will turn out with a thinner and softer caramel.

Can you freeze caramel?

Yes, you can, no problem. Take care to pack it airtight though. When you want to use or eat it take care to defrost it will in time. The caramel will have become pretty hard, so be patient before eating. Read more here on freezing caramel and its freezing point.

Applying caramel science – Recipes

After all that theory it’s time to get to work and make some caramel.

Coffee chocolate caramel ice cream - discussing how best to add chocolate chips or chunks to your ice cream without breaking your teeth upon eating! Ice cream inclusion science | foodcrumbles.com
Caramel for in your ice cream.
chocolate and peanut butter dessert pouring over caramel sm
Caramel syrup
sticky apple cinnamon rolls
Cinnamon rolls with caramel sauce

Or try these recipes! One uses the wet method to crystallize sugar, the other uses the Maillard reaction to create a nice brown sauce.

chocolate and peanut butter dessert pouring over caramel sm

Caramel recipes

Prep Time: 5 minutes
Cook Time: 30 minutes
Total Time: 35 minutes

Two recipes, both make a good caramel.

Ingredients

Recipe 1 - A smooth thick caramel, e.g. for caramel bars

  • 200g regular sugar
  • 60 ml water
  • 80 ml cream - high fat content
  • 4 drops of vanilla
  • 50g unsalted butter
  • 1/8 tsp salt

Recipe 2

  • 200g cream
  • 280g sugar
  • 120g butter

Instructions

Recipe 1

  1. Put the sugar and water in a pan, place on a medium/high heat. Take it from the fire once it has turned a nice brown colour. Do not stir, read below why.
  2. Add the cream immediately, take care, it will bubble a lot and it will be very hot.
  3. At the vanilla, salt and butter. Stir until all the butter has melted.

Recipe 2

  1. Mix the cream, sugar and 80g of butter in a pan. Take quite a large pan, when the cream starts boiling it will rise quite a bit.
  2. Place on a medium/high heat and keep on heating until the caramel has turned the right colour. Stir regularly to prevent the cream from sticking on the bottom.
  3. Once you've reached your desired colour, turn off the heat and add the remaining butter. Stir until all the butter has melted.
  4. The reason for keeping back some butter here is to cool down the mixture and prevent further browning. You could add all at the start but then there's no way to stop it if it's just gone a little too far.

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22 Comments

  1. Brilliant. Thank you. The most helpful caramel guide I have found on the internet after my failed banoffee caramel!

  2. I made penuche today for pecan rolls, and it turned into caramel. I cooked it again, let it cool to 110, beat it and turned it into a pan. Again, caramel. What causes penuche to turn into caramel? (Or, conversely, what would cause caramel to become fudgy like penuche?) Thanks in advance for any tips.

    • Hi Billie,

      Caramel turning into ‘penuche’ or a fudgy/crystallized structure happens because of the crystallization of sugar crystals. Just a few sugar crystals that come into contact with the caramel can be enough to initiate the crystallization. You can prevent this from happening by adding some glucose syrup which contains some very long molecules that inhibit this crystallization.

      The other way around, a candy that should crystallize/turn fudgy that stays liquid could be because of the presence of an ingredient such as glucose syrup. Another likely cause is that it’s not been cooked down enough. Sugar crystals will only form if there ‘too much’ sugar in your candy for it to remain dissolved. If there’s too much water, the sugar will simply dissolve. If you’ve got your temperatures and concentrations right, you can try adding a little bit of icing sugar when beating it. The sugar crystals in the icing sugar can help the other sugar crystals to crystallize by serving as ‘seeds’.

      Hope that helps!

      • Thank you! I think I had too much moisture. I let it sit in a cake pan in the refrigerator while deciding what to do with it. Miraculously, after a couple of days, it turned from caramel into penuche. I am guessing the refrigerator pulled moisture out. Hoorah. Now I can make pecan rolls. Thanks, again!

        • That’s great! A trick I have to remember :-). The fridge does tend to dry food out, which in your case is exactly what you needed. Also, over time sugar tends to recrystallize again if it can, so those two factors together seem to have come together perfectly for you! Enjoy the rolls

  3. Recipe #2 looks so easy but I am in the USA and don’t know how to convert. Do you happen to have the #2 recipe converted to an easy for me cups of ingredients recipe?

    • Hi Margaret,

      Unfortunately, converting weights to cups often isn’t straight forward (the other way around is a lot easier) since you might end up with very strange cup amounts (like 1/12 or 1/6). It’s the biggest disadvantage of using cups and spoons, that you’re not as flexible as you are with weights (hence I’m not a big fan).
      There are several online calculators that you can use to convert, but I haven’t done so myself so don’t know how ‘nicely’ this one converts for you. A simple kitchen scale nowadays isn’t expensive (they start at $10,- at Target) so that would always be my recommendation :-).

  4. Help! I am trying to make turtles, but the caramel always turns gritty and my chocolate blooms. How do I stop this?

    • Hi Candie,

      Great question. Grity caramel is almost always caused by sugar that recrystallizes. The best way to prevent this is to add some corn (glucose) syrup to the caramel. This will help prevent the sugar from crystallizing. It will also give your caramel more of a ‘pull’.

      Chocolate blooming can only be prevented by really good temperature control of the chocolate, that can be tricky for sure, a few pointers:
      – Temper the chocolate: chocolate will bloom if you do not temper it, so make sure you temper the chocolate before using it.
      – Control the temperature: don’t pour tempered chocolate over hot caramel (or vice versa) the hot caramel will re-melt the chocolate and ruin the temper again. Temperature control here is very important.

      Hope that helps!

      • Thanks for that Info. The chocolate is either tempered in a chocolate tempering machine or To 88 degrees. The caramel is cooled overnight. Despite my best efforts, the chocolate still blooms. Any help is appreciated.

        • Hi,

          It sounds like you’ve tried various things already so I would focus on trying to eliminate a few factors by doing a few tests. With candy making getting the details right is important, but since I can’t see what you’re doing exactly, I would suggest you try a few of the following. For more detailed discussions please send us a note with some more process & recipe details and we can see if we can be of more help!

          • You will want to know whether the blooming of the chocolate is caused by the caramel or an incorrect tempering process. I would suggest you store some tempered chocolate without the caramel and some with the caramel. That way you know which of the two might be the problem.
          • Dealing with tempered chocolate is the most challenging part of working with chocolate for sure. Whether the temperature you’re using is correct depends on your chocolate, if you got it from a supplier I would suggest you reach out to them to ask for the optimal tempering temperature to ensure you’re in the correct range. Different chocolates can easily vary a few degrees in their optimal temper temperature.
          • Tempering chocolate either requires a lot of experience (once you’ve done it often enough you can ‘feel’ whether chocolate is correctly tempered) or good measuring. If you have access to a tempermeter you could use that to check whether your temper is indeed correct.
          • Even a well tempered chocolate can bloom if you don’t cool it properly. Generally freezing freshly tempered chocolate is not a good idea, nor is very harsh cooling. The cold can undo some of the temper.
          • If the bloom seems to be caused by the caramel, consider changing the type of fat you’re using in the caramel (or lowering the fat content). Fat from the caramel can migrate into the chocolate, causing bloom.
          • Hope this helps!

  5. Does golden syrup also work as a crystallisation inhibitor ?

    I prefer the dry method, but sometimes find the caramel browns too much before all the sugar is dissolved (even when heat is reduced). What temp should I be aiming for dissolving and what temp should I be aiming for for caramelisation ?

    • Hi Shanon,

      Two great questions!

      Let’s look at the golden syrup first. Golden syrup is mostly made up of ‘invert sugar’. This is sucrose (which is the ‘regular’ sugar you’ll find in supermarkets) that has been broken down into glucose and fructose. Invert sugar does not crystallize easily so can indeed limit crystallization. That said, invert sugar is sweeter than sucrose so will impact your recipe. Glucose and fructose will caramelize at a slightly different temperature than sucrose, so keep that in mind as well.
      To compare, corn syrup is a mixture of small sugar molecules and larger molecules. These larger molecules prevent the crystallization of sugar. As such, the mechanism is somewhat different. Also, these longer molecules will help to give ‘stretch’ to a caramel, enabling you to pull a caramel into long strands.

      To look at question two, it seems like you’ve got some challenges with even heat distribution. Some parts of your pan may be hotter than others, causing some parts to crystallize whereas others haven’t even dissolved yet. This is a very common challenge. You don’t want to shake the pan too much to prevent crystallization, but you could move it around over your heat source or turn it to help even out hot spots. What you’re doing with a reduced heat helps as well, but clearly isn’t enough. Lastly, thicker bottomed pans can help as well. A very thin pan has hot spots more easily than a thicker one which can spread the heat around more, so might be worth looking into that as well.

      In my experience measuring the temperature at the end is tricky in a caramel. Once you see caramelization occurring before all of it has dissolved, turn down the heat, turn the pan and if nothing helps, you might just want to add a little water (be very careful, the sugar will be super hot, so it will probably splash and splatter). The water will help dissolve the sugar and will cool it down a little to give the colder sugar time to catch up.

      Hope that helps!

  6. Hello,
    I have a caramel recipe that is so delicious, but the caramels are oily. Any idea how to prevent that from happening? I did substitute toasted sugar for regular sugar.

    • Hi Donna,

      Oil leaking out is a common problem for caramels. When you’re making caramel with quite a bit of fat (e.g. butter or oil) you are essentially making an emulsion of water and fat. Once you ‘break’ this emulsion the oil will leach out. It sounds like in your case your caramel hasn’t completely split but does have more oil on the outside than you’d like to. Hope the following tips can help:

      • Good stirring up to the end helps to keep the different phases mixed well (we mentioned this one above as well, just repeating it to be complete).
      • You can consider reducing the fat content slightly. It seems like you don’t have a lot of problems with it splitting, so possibly taking out 10% of the fat/oil can help reduce the oiliness. Reducing it by that amount won’t affect the cooking process significantly, nor will it really affect the texture.
      • Your substitution of sugars shouldn’t matter too much in this case. Sugar plays a minor role in stabilizing an emulsion and the sugar change you’ve made shouldn’t have that much of an impact on a caramel since you’re already heating the sugar quite a bit.
      • In caramels milk powders (or dairy milk) as well as butter (instead of oil) contain some natural emulsifiers that help the oil and water to stay together and prevent separation. If you’re not using any of these, you could try adding those (or increasing them a little).
      • Hope one of those helps you improve your caramels even more, it sounds like they’re already delicious!

  7. How can I keep my caramel from spreading I would like them to be square shape soft and chewy. Is there a stabilizer I should use?

    • Hi Quarana,

      To get your caramel firm enough it’s important to lower the water content enough for it to become firm. Also, you can tweak the type of fat your using (one that is solid at room temperature will give a harder caramel after cooling down, e.g. butter instead of oil). Lastly, some ingredients (especially milk) will help thicken a caramel. The milk proteins can form a structure that helps hold the caramel together. It’s why substituting cow’s milk for another ‘milk’ might give very different results.
      You do not need to use stabilizers to make a firm caramel, you can do it by balancing your ingredients and process. My advice would be to look up a recipe + process that make a firm caramel and start tweaking from there.

      Hope that helps!

  8. Hello. I’m experimenting with a sauce we use for pumpable sauce as well as a thicker version for drizzle.
    50 lbs sugar, 200 ml Lemon Juice (the only thing I’ve found that’s keeps such a large batch from crystallizing).
    At temp I add 12 lbs ice to cool and thin quickly. With immersion blender add 12 lbs butter.
    I pull some out for drizzle and add 7 lbs ice – with the blender – to make the pumpable sauce.

    Here’s the new problem. Both versions separated in the fridge.
    I took some drizzle sauce out and put it in the mixer to re-incorporate.
    It turned a light beige: unusable for the purpose.

    Did I increase the butter too beyond it’s capability? How do I get these to re-incorporate?

    And, why the beige color and how can I get it back?
    (That sauce also become more voluminous. I assume I mixed air into it….)

    • Hi John,

      Thanks for reaching out! It’s a challenging question, hope the answer below helps!

      I’ll start with the ‘easy’ part: the changing color of the sauce. Yes, you’re right, based on your description I would also say this is caused by the incorporation of a lot of tiny air bubbles. Those air bubbles reflect light differently and make the sauce turn lighter. I’m thinking your sauces are pretty viscous and probably hold onto that air, not letting it go again (e.g. you wouldn’t have this problem with water, all bubbles would be gone in a few seconds). You could try to gently heat up the sauce to make it a little more fluid, which makes it easier for the air to escape. Maybe gently stir it as well to help the air escape. Note, this might not help with incorporating the fat, but it can help in getting rid of the air.

      I’ll continue with the second easiest answer: you’re absolutely right that lemon juice helps prevent crystallization. It does so by breaking down some of the sugar (sucrose) into its individual components (glucose & fructose). It is great at preventing crystallization, do keep in mind that it does slightly affect the sweetness and consistency of your syrup. This isn’t a problem if you make it the same way every time, but don’t leave the syrup + lemon juice at high temperatures (e.g. after cooking) for a long time since it will continue to break down the sugar and thus change over time. Just something to watch out for!
      If you’re looking for something else, corn syrup/glucose syrup can help as well, though you’ll need more than just 200ml. You could start trying it with 5 lbs of corn syrup and go from there.

      Lastly, the splitting problem of your caramel. This is not an uncommon problem to occur, I’ve had it happen several times. Since you’ve just got sugar + fat (with only very little proteins from the butter) you have nothing to help stabilize that caramel here. A few things you could try:

      • Add a little bit of emulsifier (you could try lecithin, this is a natural emulsifier found in soy as well as eggs) to help the fat and water stay mixed.
      • Controlling temperature, you could try using softened butter (slightly warmer) to lessen the temperature difference and make the butter a little more stable. Opinions and experiences here differ though, some recipes may actually call for adding the butter when the sugar is still hot to mix through completely. In other words, I would focus on experimenting with temperature, but am not 100% sure which temperature mix works best.
      • Keep in mind that butter fats turn solid in the fridge. As such, once the recipe has cooled down it should be pretty stable. You could try to prevent the separation by mixing through the sauces a few times as they’re cooling down to ensure they don’t split. Once the fats have solidified, it’s less likely to split.
      • Good luck!

      • Well, thank you for replying so quickly.
        In my slight-desperation meanwhile, I did the very things you prescribed.
        Heating the (thicker) drizzle up again brought back the color.
        Stirring it occasionally while cooling kept it from separating, which means
        the ingredient balance is good, I just need to pay attention to my cooling process.
        I’ll try several variations when cooling the next batch and see what works best.

        Thanks so much for sharing your knowledge and experience!
        John

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