Balancing technological sugars in ganaches

Sucrose molecule © Karl Harrison 3DChem.com

Having a basic understanding of sugars and how they interact in ganaches is an important piece of knowledge every chocolatier should delve into. Chocolatiers often overestimate the shelf life of their bonbons. In hotels and restaurants, this post is probably a little bit less important, but even in that case, I would urge you to keep reading as some of the properties of the different sugars I’m covering here will also apply to pastry preparations and can improve their quality, taste and shelf life. We often talk about ‘sugars’ in ganaches. The late Jean Pierre Wybauw recommends a minimum ‘sugar’ content of 25% while Ramon Morato goes even further and recommends a minimum of 30% to achieve a balanced recipe with optimal texture and shelf life. It’s important to note that we talk here about ‘sugars’ as a group and not sucrose, commonly known as ‘caster sugar’ or ‘granulated sugar’  which is more specifically a disaccharide consisting of glucose and fructose molecules. To avoid confusion, I will only refer to this sugar as sucrose in this article. Sucrose is probably one of the worst sugars to use in ganache, to understand this we need to look at the state of sugar at room temperature: it’s a coarse crystal. Because of this Sucrose will, over time, re-crystallise and release water in the recipe leaving you with a reduced shelf life and subpar texture.

Why you need to include sugars in your ganache

A ganache is an emulsion; meaning it’s a mixture of water and fat. As water is what most microorganisms need to thrive, we need to “bind” this water to make it unavailable for those microorganisms to multiply. The value of “bound” versus “unbound” water is reflected by the so-called ‘Water Activity’ or simply put ‘AW.’ A higher value equates to a higher amount of unbound water, which means the circumstances are more beneficial for microbial growth. A water activity measurement of 1 means there is 100% of free water, a measure of 0.5 means there is 50% of free water.

When we look at a ganache that is made up of just cream and chocolate, the score is usually well over 0.90. If you want to be able to plan your production and not produce your entire collection every other day, you will have to find a way to reduce the water activity. Sugars are your primary tool to achieve this. Adding certain acids also help to lower the chances of microbial growth, but this will not be suitable for every flavour profile. I’m also not a fan of resorting to alcohol as you will effectively cut out one-fifth of the global population as potential buyers of your product.

Which sugars are suitable

So if we can’t use good old sucrose in our ganaches, which ‘sugars’ can we use? Typically a combination of different sugars will do the job, to make a decision we there are a few things we need to know.

Sweetening power

If we consider our ganache will contain anywhere between 25 to 35% of sugars. The sweetening power of the sugars we will use will be of critical consideration; after all, we don’t want overly sweet chocolates. To understand this, we consider sucrose the benchmark, which has a sweetening power of ‘100’. In the below table I’m limiting myself to sugars we will typically use in chocolate, ice cream or pastry.

If we look at the above relative sweetening powers of the different sugars, and we keep in mind we need to reach a total of 30% of ‘sugars’ (including the sucrose which is already present in the couverture we will be using) we want to avoid using too many sugars which have a high relative sweetness.  Especially when we need to achieve a longer shelf life and need to increase the sugar content even more, this becomes important. Relying solely on invert sugar for example will result in a product that is too sweet, combining with a combination of sorbitol, glucose and or glycerol is the better way to go for creating the optimal balance between shelf life, balanced sweetness and optimal texture. Below I will break down several different sugars that I often use in my chocolates.

Glucose

Glucose molecule

Benefits of glucose in chocolate are:

• Binds water thus reduces free water content. (lowers water activity)
• Prevents re-crystallisation of sucrose in the recipe.
• Makes a more elastic ganache.
• Slows down the drying of the ganache.

Because glucose prevents re-crystallisation of sucrose, I recommend to always add a small amount in your recipes for this reason alone. Glucose syrup contains water, and so that will need to be accounted for in the total water content of the recipe. The amount of water is referred to in ‘Beaumé’, and typically glucose syrups come in the following forms: 43 BE = 80% dry substance 45 BE = 85% dry substance For ganaches, it’s advised to opt for 45BE as you will end up adding less water to the recipe. Another point to keep in mind is the ‘Dextrose Equivalent’ abbreviated to DE. Dextrose is the product of hydrolysis of starch. The further the hydrolysis process proceeds, the more reducing sugars are produced, and the higher the DE. Typically we find glucose syrups varying from 42 DE to 63 DE in industrial settings. The lower the DE, the higher the amount of dextrin and the lower the amount of reducing sugars.  Higher DE glucose syrups have low amounts of dextrin and high quantities of reducing sugars. Note: 

• Dextrins are low-molecular-weight carbohydrates produced by the hydrolysis of starch or glycogen.
• Examples of reducing sugars are: glucose, fructose, lactose and maltose or simply put monosaccharides.
• Glucose syrups with a higher DE and thus a high amount of reducing sugars are sweeter.

For shelf life optimisation it is recommended to use 45DE glucose syrup, it contains a good amount of reducing sugars which are more effective at binding water and preventing drying out of the ganache. A lower DE glucose syrup will make the syrup more viscose.  Note: while glucose certainly has a place in a ganache it is relatively ineffective compared to other sugars in reducing water activity, to have a long shelf life glucose syrup should only be one element in the arsenal of water activity lowering ingredients in the ganache.

Invert sugar (commonly known as Trimoline)

Fructose & Glucose molecule

Invert sugar is sucrose inverted by the enzyme ‘invertase’ and so becomes a mix of glucose and fructose (approximately a 50/50 ratio). Invert sugar is particularly hygroscopic (water-attracting) and therefor an excellent addition to any ganache to make sure the ganache doesn’t dry out. In doing this, the water activity will also drop significantly. Honey is almost identical to invert sugar, and they can be substituted with each other. A few notes of caution:

• Excessive use of invert sugar will make the ganache sticky and soft, which could be a significant issue for chocolates that will be enrobed.
• It’s advisable not to heat invert sugar over 70 degrees C as fructose will start to degrade at this point, resulting in a loss of water activity lowering properties.
• Invert sugar is quite sweet (sweetening power of 125%), so go easy on it.

Sorbitol

Sorbitol molecule

Sorbitol has a bad rep. For being an ‘E-number’. Let me set the record straight though; sorbitol is a naturally occurring ‘sugar alcohol’ and can be found in grapes, pears and many other fruits! It is true that in excessive amounts, sorbitol can have laxative effects, it would take some severe chocolate-eating however, to get anywhere near the necessary dose for that. Sorbitol has quite strong water activity lowering properties while only boasting 50% of the sweetness sucrose has, because of this it can be used in relatively larger quantities compared to invert sugar without the end product becoming overly sweet. The recommended dose of Sorbitol is 5 – 10% calculated on your recipe.

Glycerol

glycerol molecule

Another one with a bad rep. For similar reasons to sorbitol. Like sorbitol, glycerol is a naturally occurring sugar alcohol.  Some chefs claim that they don’t like the texture, but I would challenge anyone to taste several chocolates blindfolded and point out which ones have glycerol in them…  I’ll be impressed if anyone can guess them all correctly. (if the ganaches were balanced correctly of course.) Glycerol has the most potent water activity lowering properties of any sugar we have discussed in this article, if a long shelf life is a must (think beyond four months without freezing) I find it challenging to achieve this without the inclusion of glycerol. Key points of glycerol:

• Glycerol is approx. 2 times stronger than sorbitol at binding water or lowering water activity.
• The dose is 3 – 5 %, exceeding 12% will result in a bitter unpleasant after taste.
• Glycerol has a sweetening power of 60, so quite a bit lower than sucrose.
• Glycerol is a sugar that is naturally occurring in our bodies amongst other places.

Applying this in our recipes to get an optimal shelf life

Ramon Morato recommends that for optimal shelf life, a ganache should be roughly made up like this: Max. water content: 20% sugars content +/- 30% Cocoa butter +/- 21% Dairy fat +/- 15% A real-life example of such ganache would be:

Cream 340g Invert sugar 90g Glucose 40g Sorbitol 100g 65% chocolate 620g Anhydrous butter 140g

Or broken down more:

To get to this calculation, we need keep in mind: Cream (UHT) contains 35% dairy fat and 65% water 65% couverture contains 35% sucrose and 40% cocoa butter Glucose syrup contains 85% dry substance and 15% water.

Contrary to what you would probably expect, this ganache made under normal circumstances would have a water activity reading of about 0.78, so in optimal conditions only a shelf life of about 6 weeks. As you can see if you want to exceed 8 weeks we will need to consider the inclusion of glycerol.

Note: When shelf life is not essential, we can increase the water content to our liking (within reason), In commercial chocolate shop settings however it is vital to follow the guidelines outlined in this article. People tend to overestimate significantly their shelf life, which could ultimately lead to expensive lawsuits, don’t let it get to that! 😉 Update 02/07/2019: Since last writing this blog post, I took a masterclass with Alexandre Bourdeaux, one of the leading Barry Callebaut chefs and technical advisors, on shelf life. During those days, I learned that he broadly agrees with the ratios outlined in this post but to make things easier for us chefs to calculate our recipes faster he created a software called Ganache solution, I was sceptical on its use but after being shown how easy it is and how much time it can save I invested in this software, I would highly recommend professional chocolatiers to use this software. Note: The properties of these sugars extend beyond the world of chocolate bonbons. Including a % of invert sugar in baked goods, for example, will keep the product moist longer and thus increase shelf life. If you would like to learn more about this topic, two books have helped me a lot in understanding this topic better: One is the collection ‘Fine chocolates’ by J.P. Wybauw or the book ‘Chocolate’ by Ramon Morato.

‘Chocolate’ by Ramon Morato

Fine Chocolates collection by J.P. Wybauw

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