cherry cake

The Science of Preserving Cherries (+ How to Use Candied Cherries)

You can find these bright red, slightly translucent fruits on top of cocktails, or topping off your refreshing sundae. The British also like to put them on top of their cakes. I’m talking about glacé or candied cherries. They have a peculiar flavor, are full of sugar, have lost the bite of a fresh cherry and in all honesty don’t taste that much like cherries anymore.

If you’ve ever watched the Great British Bake Off show you may have seen Mary Berry’s cherry cake come by. It’s full of these candied cherries and has a classic look to it for sure. While replicating her cake I decided to dive into the science of these fascinating cherries. Why even candy them? And how are they even made?

Candied, glacé and maraschino cherries

Candied cherries are cherries which have been soaked in sugar syrup for a long period of time, over time sucking up the sugar solution. It’s a century old method used to preserve cherries since fresh cherries don’t keep long, especially if you don’t have refrigeration. Candying the fruit preserves the fruit because of the high sugar content. This makes it an inhospitable environment for spoilage micro organisms. It is the same reason why transforming fruit into jams keeps it for longer. The advantage of candying though is that the fruit actually keeps its shape in the process (although it does lose some of its bite).

Within the world of these preserved, candied cherries there are quite a few different types. There are candied cherries, glacé cherries, amarena cherries and Maraschino cherries. They are all made using this sugar syrup, but differ in some minor aspects.

Glacé & candied cherries

The terms candied and glacé (or glazed, or glaceed) cherries tend to be used for the same or at least very similar cherries. The Brits tend to use glacé cherries, whereas Americans use candied ones, but they’re made in the same way, as we’ll see later. In some cases the glacé version is a candied cherry with an additional coating transparant coating.


Maraschino cherries have a slightly more complicated history to them. Originally maraschino cherries could only be called so (in the US at least) if they were by submerging them in maraschino liquor. This maraschino liquor is also made from cherries. However, during prohibition in the US, with alcohol not being allowed anymore, non-alcoholic maraschino cherries were developed and allowed to be called as such. Nowadays most, Maraschino cherries don’t contain any liquor. Instead, they are actually quite similar to the other two cherries, although their flavouring is markedly different.

How candied cherries are made

Even though candying is quite a common process, it isn’t easy to find a good description of the production process. In reality different production locations might do things slightly different.

fresh sour cherries
Ripe sour cherries, ready to be picked

It starts with cherries

Any candied cherry starts with a fresh cherry. There are two main types of cherries: sweet & sour. The sweet ones are those that you will tend to find in the supermarket, as the name says, they’re sweeter than the sour ones. However, they are also a little more tricky to grow, with lower yields.

That is one of the reasons, sour cherries are used for processed cherry products, of which candied cherries are one example. Since they are easier to grow, it is more profitable to use these. Their slightly sour, tart flavour also makes them less overly sweet once candying them (with a lot of extra sugar).

Adding sugar

Candying cherries is a preservation process. You’re essentially trying to get as many sugar inside that cherry as you can to properly conserve it. You can’t just soak your cherries in a sugar solution though. First of all, the cherry won’t readily let moisture in or out, it will go quite slow. Second of all, osmosis comes into play (remember turgor?).

If you place a plant cell, which has a low sugar concentration, let’s assume it’s 5%, in a highly concentrated sugar solution the principles of osmosis say that the two sugar concentrations want to become equal. Since sugar can’t travel through a cell as fast as water can, that will mean that a lot of sugar from the cell will go into the sugar solution. This should decrease the concentration of sugar in the solution and increase the concentration of sugar in the plant cell (since there’s less water but still the same amount of sugar).

As a result, the cherry will wrinkle and collapse and it’s structure just doesn’t look right any more. To get a nice round smooth cherry with enough sugar, you need to take some more steps to get there a bit more slowly.

Preparing the cherries

In order to make sure the sugar syrup can properly enter the cherries, the cherry structure will have to be broken down somewhat. This is why they often get a quick heat treatment. You want to heat them long enough for them to become softer and more open for sugar syrup, but not that soft that they fall apart.

But it’s not just the sugar syrup that has to come in. Have you ever noticed you the candied cherries all have the exact same colour? Well, that’s not because the cherries just happened to have the same colour coming off the tree. Instead, their being dyed. But, to get an even colour dye, you want to make sure that the natural colour of the cherry doesn’t interfer. This is why most candied cherries tend to be bleached at the start of production.

Bleaching is done by placing the cherries in a solution of sulphur dioxide. The resulting sulphite and other sulphuric components have a bleaching effect. For manufacturers bleaching can be tricky since it can ruin the texture of a cherry. This is why calcium salts are added, these help to keep the cherry together and prevent it from becoming too mushy.

At the end of these steps you’ve got some colourless, soft, but firm and cherry shape like cherries.

floured dried maraschino cherries
Cherries ready to be used in cake

Colouring & sweetening the cherries

Now it’s time to actually make those candied cherries. Osmosis is still a force to reckon, so cherries will not be placed into the desired final sugar concentration at once. Instead, the cherries will be placed in ever increasing concentrations of sugar syrup. This allows the sugar to properly penetrate the full cherry without disrupting the structure. Depending on the exact process used, this process can take days or weeks. Although we’d expect current industrial processes have managed to speed things up considerably.

Compared to the sugar process, colouring the cherries is easy. If you’re using an artificial colour, you can add it just before you start sugar syruping the cherries. Since natural colours tend to be somewhat less stable, they tend to be added towards the end, to ensure the colour doesn’t get lost during the process.

Finishing it off

At this point you’ve got your candied cherry. All that’s left to do is to rinse the cherry to ensure excess sugar solution is gone and to dry them so they don’t stick together too much. Since there’s a lot of sugar in there, they won’t actually dry fully, but that’s ok.

How maraschino cherries are made

Maraschino cherries are made in just about the same way as the candied cherries we just discussed. The composition of the sugar syrup might be slightly different, but the principles are all the same.

But they are different of course. First of all, it’s the flavour. Since maraschino cherries used to be made with a maraschino liquor, that lack of taste has to be made up for. Nowadays that flavour is mostly almond oil. So if you feel like using almond flavoured candied cherries, you could give these maraschino cherries a chance. The only other main difference is that they’re packed in the syrup, so you might want to dry them before you use them in a recipe that calls for candied cherries.

Troubleshooting preserved cherries

Now that you know how these cherries are made, a bunch of questions might pop up. Let’s discuss a few that we thought of in the process of understanding all these different cherries.

Why doesn’t sugar crystallize on the cherries?

If you’ve tried making your own caramel or candied foods, you might have run into some issues with crystallizing sugar. All of a sudden your sugar crystallizes and gone is your smooth, soft appearance. You can prevent this though buy using the proper combination of sucrose and glucose sugar. Some cherries don’t even contain sugar as an ingredient anymore, but just contain a sugar syrup like fructose or glucose. These syrups won’t crystallize, so easier on manufacturers.

Where do those green candied cherries come from?

You mean those Christmas green coloured cherries? Well, they’re made the exact same way as the red cherries, but this time a green colour is added. Sometimes they also have a different flavour (peppermint candied cherry anyone?).

Where they come from? I’ assuming that a smart manufacturer back in the day realized that it would be a lot nicer to have both green and red in Christmas bakes. Smart of course, because now you have to buy two tubs of cherries. Whether that’s the true story, we’re not sure, let us know if you do know!

What about amarena cherries?

We won’t dive into the deep details of yet another cherry, there are quite a lot of cherries in this article already. That said, the amarena cherry is Italian and it’s actually quite similar to the traditional maraschino cherry, the one that was made with liquor. The amarena cherry also has a lot of sugar inside, but has more of its original cherry flavour and structure.

Mary Berry cherry’s cake

You must be hungry after all that cherry studying. Also, you might want to head off to your supermarket and see what type of cherries they have lying around. In the recipe below (from Mary Berry, as the name says) you’re supposed to use glacé cherries, but we used maraschino cherries that we drained of excess moisture and that worked just fine as well. As long as you use a preserved cherry, and not a fresh one, you should be quite all right.

cherry cake

Candied cherry cake

Prep Time: 15 minutes
Cook Time: 40 minutes
Total Time: 55 minutes


  • 175g butter
  • 175g sugar
  • 3 eggs
  • zest of one lemon
  • 50g ground almonds
  • 225g flour
  • 1 tsp baking powder
  • 150g glace/candied/maraschino cherries, rinsed (to get rid of excess sugar), dried with a paper towel and cut into four

Optional decoration

  • Almond slices, lightly roasted


  1. Mix the butter and sugar. Add the eggs and mix through.
  2. Take the zest, ground almonds, flour and baking powder and mix in with the butter mixture. Mix until it's completely combined, but do not overmix, this can dry out the cake.
  3. Take the cherries and mix them with 1 tbsp of flour. This helps to prevent them from sticking and helps to mix them through the dough properly.
  4. Fill a bundt cake pan (24 cm in diameter) with the mixture.
  5. Bake in the oven at 180C for 40 minutes, or until a skewer comes out clean.
  6. Decorate with almonds or your favorite cake icing.

Sources & further reading

Want to try making your own ‘real’ Maraschino cherries? Have a go using a recipe from Serious Eats.

Modern Technology of Confectionery Industries with Formulae & Processes (2nd Revised Edition), Minni Jha, 2003, p. 49, link

Fruit Processing, D. Arthey, P.R. Ashurst, 1995, p. 183, link

The Chemical and Preservative Properties of Sulfur Dioxide Solution for Brining Fruit, C. H. PAYNE, D. V. BEAVERS, and R. F. CAIN,1969

Science, Service, and Specialized Agriculture: The Re-Invention of the Maraschino Cherry, J. Christopher Jolly, 1998, Master thesis at Oregon State University

Foods & Nutrition Encyclopedia, Two Volume Set, Marion Eugene Ensminger, Audrey H. Ensminger, 1993, p.389, link

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