honeycomb too high baking soda content

The Science Behind Caramelization & A Honeycomb Recipe

Never knew that a little bit of a staple white powder could cause so much bubbling and flowing. Resulting in a super crunchy, slightly sweet/slightly bitter snack. No clue what we’re talking about? It’s honeycomb, made from sugars & baking soda. When making honeycomb you boil sugar and sugar syrup until it’s a nice brown. At that point you add baking soda to the extremely hot sugar mixture. This causes the sugars to bubble and puff in a spectacular manner.

Even though the addition of baking soda most definitely is the most spectacular part of making honeycomb, there’s a lot more chemistry involved. The transformation of pale sugars into a beautiful brown consistency involves a lot of chemical reactions. This browning is called caramelization and is the topic of this post. Some hard core chemistry today.

What is caramelization?

Caramelization is a browning reaction in food, in other words, the reaction creates molecules with a brown colour. Caramelization is, just like the Maillard reaction, an example of a non-enzymatic browning reaction. This means that the browning occurs without the interference of enzymes. Enzymes can catalyze certain chemical reactions as they do for instance for browning of bananas. During caramelization sugars are transformed into brown colours and aromas.

honeycomb with ideal amount of baking soda

Temperature of caramelization

Caramelization requires high temperatures to get going. The temperature at which this occurs depends on various factors. The first, and most important, is the type of sugar. Regular sugar (sucrose) and glucose start caramelizing at 160°C. Maltose, quite a common ingredient in corn syrup, on the other hand only caramelizes at 180°C whereas fructose can caramelize at 110°C.

Caramelization reaction mechanism

When using regular sugar the first step in the reaction mechanism is the decomposition of this disaccharide into two monosaccharides. Part of these sugars will decompose into smaller molecules, often aromas. A lot of aromas are formed during the process. Diacetyl is a very common one, other examples of less well known compounds are: alsohydroxymethylfurfural (HMF), hydroxyacetylfuran (HAF) or furanones such as hydroxydimethylfuranone (HDF) and dihydroxydimethylfuranone (DDF).

A large portion though will participate in reactions to form large brown molecules. These monosaccharides will first react to form a disaccharide. These will continue to react into larger molecules. This is called oligomerization. In this process three main coloured structures are formed:

  • Caramelan (C12H12O9)
  • Caramelen (C36H18O24)
  • Caramelin (C24H26O13)

Chemists still don’t fully understand how these are formed, nor how the molecules actually look like.

Influence of acids and bases on caramelization

As I wrote in the previous paragraph, honeycomb should be heated to 150°C to get a nice brittle texture. However, you might now realize that this is still below the caramelization temperature, which is correct. However, there are other ways to speed up caramelization. One way is the modify the amount of acids or base present. As you’ve learned in my special on baking soda, baking soda can react as a base. Adding baking soda to something will make it more alkaline (or less acidic). By making it less acidic and clearly more alkaline, the caramelization will be sped up quite a bit! Once I added baking soda to my honeycomb the colour clearly darkened to a perfect golden honey colour.

The great thing about baking soda is also that it gives a lift to your product! The baking soda will form gas (see my other post on the topic) and create air bubbles in the sugar syrup. This is great because a solid sugar solution that’s been heated to this temperature will be very hard and tough to eat. But because of all the air bubbles it brakes easily and eating is no problem at all!

Last but not least, if you don’t use a pure sugar but a mixture (as is the case for corn syrup), impurities can also speed up the reaction. My honeycomb started turning a light brown at 150C, even before I added any baking powder.

honeycomb, freshly spread out

Why does baking soda work?

Ok, if you’re like me, you are asking yourselves a question now. I just learned that baking soda can form a gas (carbon dioxide) by reacting with an acid. However, we don’t add any acid to the honeycomb, why does it still work?! Great question, I like your thinking. I haven’t (yet) been able to find a conclusive answer. But here’s what I think happens.

First of all, baking soda (sodium bicarbonate) is not a very stable compound, it can react pretty easily for form a gas. When the temperatures are so very high (as is the case with honeycomb) this reaction might can ahead without the acid, it’s probably more stable for the component to be a gas any way. Second, at these high temperatures sugar starts decomposing slightly before caramelisation occurs and impurities will be present from the corn syrup. I think that at least some acidity will be present which will help catalyze the reaction even further.

Honeycomb recipe

Honeycomb requires only a few ingredients and steps. Have fun!

honeycomb, freshly spread out


Yield: 8-10 portions
Prep Time: 5 minutes
Cook Time: 30 minutes
Total Time: 35 minutes

Making honeycomb isn't as complicated as you might think, but a fun chemical balancing act!


  • 100g sugar
  • 45g corn syrup
  • 25g water (exact quantity not important, adding more will only increase the cooking time)
  • 1/2 tsp baking soda


  1. Prepare a heat resistant tray/cake tin and cover with parchment paper.
  2. Mix the sugar and corn syrup in a pan and add the water.
  3. Bring the mixture to a boil and ensure that all the sugar crystals have dissolved. If they haven't, give the pan a very gentle swirl to help them along.
  4. Continue cooking the sugars until they are 150°C (300°F). The sugars will have started to brown but only slightly, this is ok, adding the baking soda will help it turn brown rather quickly.
  5. Take the mixture off the heat and mix in all the baking soda. Do this fast. Watch out, the sugar syrup is very hot and the baking soda will cause it to bubble up a lot!
  6. Immediately pour onto the heat-resistant surface and leave to cool.
  7. Once it's cooled down, break into shards. Either eat immediately or store in an air-tight container. The open sugary structure attracts moisture easily (it's very hygroscopic). Keeping it away from air will ensure you can keep it for a few weeks.

Further reading

Interested in learning more about honeycomb? The guardian wrote a great article about honeycomb, with a lot of in depth details. The recipe I used is inspired by theirs. There are also a lot of scientific articles written about caramelisation and the like, for those interested, have look here and here.

Sciencegeist on the chemistry of caramel reactions.

Food-info.net on caramelization

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  1. As the corn syrup is just added to speed up the reaction, can the recipe use just 145g sugar cooked till 150 degrees and still get the same results?

    • Hi Shriya,
      Great question! The corn syrup will indeed lower the temperature at which caramelization occurs. However, the corn syrup here has another very important role, it prevents the sugar from crystallizing, both during caramelization as well as afterwards. Without the corn syrup you’re final texture would be different and certainly less stable. I therefore wouldn’t recommend leaving the syrup out.

  2. Hi! Recently found your blog and been lovin’ so far! Quick q: can the corn syrup be replaced by inverted sugar?

    • Hi Natasha,

      Welcome! Hope you’re finding our articles helpful :-).

      Corn syrup and invert sugar will behave slightly different, but in most cases invert sugar is your best bet in replacing the corn syrup. There are a few differences you may see:
      – Invert sugar is a lot sweeter than corn syrup, so you’re final product will be sweeter
      – Both are liquids and don’t crystallize as easily but invert sugar is a little less good in preventing it than corn syrup.
      – Invert sugar contains more smaller carbohydrates than corn syrup does. As a result, it’s a bit more prone to stickiness and being affected by high humidities. The lack of larger carbohydrates will also make the final product less stretchy (although that is less relevant for honeycomb).

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