chocolate troubleshooting – rudvik engineers

In the previous article we discussed about Fat blooming. In this article we will focus on Sugar bloom, their appearance, causes and some solutions.If you haven’t read the previous one, you can read it here –Blooming in chocolates-Blooms and defects

Close up of segment chocolate bar isolated on white background

Sugar bloom- The moisture culprit

It looks like a grainy, white, crusty or powdery film on the surface. Its differentiation from Fat bloom is that unlike fat bloom it is dry and rough to touch, which creates a sensation that the smoothness of chocolate has turned into the roughness of a sandpaper. To a consumer, it looks like small sugar crystals have formed on the surface, which in fact have.

The sugar bloom happens when moisture comes in contact with the chocolate. As we know sugar has affinity towards water, so when the moisture comes in contact with chocolate, the sugar gets dissolved in it and when the misture gets evaportaed, the sugar is left behind in crystal form on the surface of the chocolate.

Common causes and solutions

High Ambient Humidity During Production or storage

Chocolate is highly hygroscopic, which means it readily absorbs moisture. When the relative humidity is higher than 55%, the water vapor gradient pressure between the surrounding air and the chocolate causes the moisture to move towards the chocolate , resulting in condensation happening on the chocolate surface. Simply put, the surrounding air has more water than the water loving chocolate surface, so the moisture moves from a high moisture reservoir to the low misture reservoir which is the the chocolate. This can happen even if thare are no drastic temperaturee changes.

Solution :- Maintain a controlled environment with relative humidity below 55%. If possible maintain it between 45-50%. This controlled environment should be maintained in production, packaging and storage areas. This will prevent condensation.

Drastic Temperature changes

Moving chocolate from a cold environment that is, a fridge or a cold room, to a warm room gives rise to dew point condensation. The surface of the chocolate is cold and so it is below the dew point of a warm atmospheric air. This results in water droplets forming on the chocolate surface.

Solution:- A routine should be made where the temperature gradually rises from cold to warm. This can stop moisture on surface.

Storage Temperature

Intuitively we would like to think that the lower the temperature is , the faster it will be solidify. While it may be true in some parts, but inevitabily when the chocolate comes out of the fridge the delta or the difference in temperature will be so high that chances of dew point condensation will become very high.

Solution :- The chocolate should be stored in a consistent , cool and dry temperature range, ideally 18-20 degree C.

Wet molds or equipment

Any residual moisture which is left in the molds or the surface of the equipment in which the chocolate is made or prepared, can seep into the chocolate and cause havoc.The free water dissolves the sugar more readily and the probability of sugar bloom happening becomes very high.

Solution :- Please ensure that any and all equipments which comes in contact with chocolate is perfectly dry. Molds can be warmed slightly above the melting temperture of chocolate which further stops thermal shocks.

Fillings with high mositure content

Chocolates with high moisture content fillings, such as fondants, caramels or ganaches, are highly prone to moisture migration. Here the process is opposite of the high ambient humidity factor. As the filling has a higher moisture content, the water wants to move to the lower moisture content region which is the chocolate itself. Add to that the affinity towards moisture of chocolates. This water then dissolves sugar during its way out and after evaporation sugar blooms are left.

Solution :- Use fillings with low water activity.Other remedy can be to integrate fillings with things which have a higher moisture affinity than chocolate or sugar. some examples can be sorbitol or invertase.

Type of sugar

Sugar in itself is highly hygroscopic. But certain sugars are more hygroscopic than others. Types of brown sugars or low grade sugars dissolve water more readily and can cause sugar bloom.

Solution:- Any sugar used must be of high quality. Double check before incorporating sugar into the chocolate that it has not absorbed moisture during storage.

Packaging

We have discussed about importance of proper packaging in one of our earlier articles which you can read here(Can Chocolates go bad?). If the packaging is not moisture sealed, the moisture can reach from the atmosphere into the chocolate. This issue can get out of control very fast when the chocolate is being transported or stored in uncontrolled conditions.

Solution :- Use high-barrier, moisture-proof packaging materials, such as laminated foils or specialized plastic films. Ensure that the packaging is hermetically sealed to create a moisture- and vapor-proof barrier

Surface pores and cracks

The microstructure of chocolate can get compromised by rapid cooling or improper tempering leading to small cracks or pores on the chocolate surface. These cracks provide a way to the moisture to penetrated the chocolate and come back up with dissolved sugar, causing Sugar bloom.

Solution: Improve the tempering process to ensure a stable, well-structured crystal lattice of cocoa butter. Control the cooling curve to prevent thermal stress that can cause cracking.

Starch or powder coating

Some chocolate confectioneries are coated with starch or some powders before packaging. If these starch or powders are high in moisture content, it can cause sugar bloom.

Solution :-Use non-hygroscopic, inert dusting powders. Ensure the application environment is dry and the powders are stored properly. Alternative release agents that do not contain moisture are also a viable solution.

Sweating

Some centers which are primarily sugar based, release moisture over a long period of time in warm conditions which is called sweating. If adequate barrier is not coated, this moisture can seep into chocolate and cause sugar bloom.

Solution:– This is an issue of formulation and is best addressed by controlling the moisture content and water activity of the center. Adjusting the syrup’s composition or adding moisture-binding agents can mitigate this issue.

We hope that the above articles has helped you in determining the probable causes of Sugar Bloom and get an idea of their probable remedies.

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A lot of hardwork, planning and meticulous timing goes into making chocolates. The chocolate maker wants nothing but the chocolate they have put so much work in , to turn out delicious , melt in the mouth and silky for the person enjoying those chocolates. However, nothing pains the chocolatier more when the chocolate shows signs of trouble. Trust us, we have been there and it is harsh and demotivating. A thin white film on the chocolate , either slippery or powdery which seems to ruin all the hardwork.

We are here to let you know that please do not despair. It is the most common problem which happens in both pure and compound chocolates. The first step in removing these white films is understanding what these chocolate defects are and the root cause for them. At Rudvik Engineers we have seen it all and in this article we will try to demystify, troubleshoot these unwanted defects in your otherwise sublime chocolates.

What is “Bloom” and Why Does it Happen?

“Bloom” is the general term for the unwanted white or grayish film that can appear on the surface of chocolates. It can be broadly categorized into two main types: fat bloom and sugar bloom. Both of them are signs that your chocolate’s integrity has been compromised, though their origins and solutions differ significantly. In this article we will focus on fat bloom.

Fat Bloom:- The slippery culprit

Appearance :- It appears as a dull, grayish, or white powdery film that makes the chocolate appear old or stale. It feels greasy to the touch, and the chocolate loses its characteristic snap and shine.

Reason:- What is happening here is that the cocoa butter present in the chocolate is moving to the surface due to the rearrangement of the crystalline structure of the chocolate. We have explained about the crystalline structure of the chocolate and the best variant which Beta V where the chocolate is most stable in our earlier article …Understanding Fats in Your chocolate – Part 2.

As stated in the above article Cocoa butter can exist in several different crystal forms (polymorphs also known as polymorphism in chocolates). When chocolate is improperly tempered, or exposed to fluctuating temperatures, the unstable cocoa butter crystals migrate to the surface and recrystallize into a larger, less desirable form (Form VI), which scatters light and appears white. Think of it like a beautiful brick wall where some bricks (fat crystals) have started to push their way out and create an uneven surface.

Common Causes of Fat Bloom

Improper Tempering

The most common of all reasons of Fat bloom is improper tempering. If the chocolate has not went through the proper temperature cycle to attain the Beta V crystalline structure, any further temperature difference can break the weak structure and cocoa butter can migrate to the surface , causing Fat Bloom. Read more about Chocolate tempering in our article Why chocolate tempering is a must.

Storage Conditions

We have already discussed about temperature fluctuations during tempering. However even when a chocolate is tempered correctly, improper storage conditions can push the cocoa butter on the surface. This can happen when the frequency of temperature changes(even a small change of 2-3 °C) during storage are very high.

Incompatible Fats

In the case of Compound chocolates, if the fat used or the blend of fats used are incompatible with the cocoa particles or sugar particles, these fats can then move to the surface , causing Fat bloom. Read more about the compatibility of fats in chocolates in our article Understanding Fats in your chocolate- What you need to know.

Particle Size Distribution

Chocolate PSD- Credit :-Determination of chocolate melting properties by capacitance based thermal analysis (CTA) – Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/Particle-size-distribution-in-chocolate-at-different-times-during-refining_fig3_320961368 [accessed 10 Aug 2025]

In one of our previous articles , The importance of micron size in chocolates we discussed about how much percentage of particle in the chocolate are around or less than the required particle size. This is called Particle Size Distribution , PSD. A sweet spot for the PSD is that 90% of particles present in the chocolate should be between 18-22 microns. If you keep reducing the particle size or rearranging the PSD, the chocolate will sure become more homogenous, but the surface area of the total particles present will increase. This can create a greater interlocking between the particles, which can inturn increase the chances of cracks to develop , from where the fat can move to the surface.

Emulsifiers

Emulsifiers are one of the key ingredients which hold together cocoa particle, sugar and fat. You can read more in our previous article Emulsifiers-Sweet secret to perfect chocolate texture. However the type of emulsifier being used, its source and its concentration also affects its compatibility with the fat being used , which if used incorrectly can cause the Fat to migrate.

Porosity

The internal pore structure of the chocolate matrix can also give rise to FAT migration. This can happen during Refining, grinding or conching stage.

Some solutions

Correct Tempering

This is a no brainer. The correct temperature cycle has to be done, which is different in case of different chocolates.

For milk chocolates

Complete Melt out – 45-50 °C

Controlled and Rapid Cooling – 27-29 °C

Reheating- 29-31 °C

For Dark Chocolates

Complete Melt out – 50-55 °C

Controlled and Rapid Cooling – 28-30 °C

Reheating- 31-32 °C

This cycle alongwith continuous agitation ensures that the correct Beta V crystals are formed which give rise to a stable, shiny chocolate.

Storage Conditions

A consistent temperature range which is narrow, has to be maintained, ideally 18-20 °C, with minimal fluctuations

Humidity must be kept between 50-55 %.

Advanced packaging can also be used like barrier films.

Incompatibility with Fats

Using high quality cocoa butter with a consistent triglyceride profile.Why is it needed you ask? Well if you have gone through our earlier article as mentioned above, triglycerides with similar melting and crystallizing behaviors help maintain stable fat crystals which is the Beta V. Too much variability in triglyceride types can interfere with proper crystal formation, leading to unstable crystals that are more prone to migrate to the surface, causing Fat bloom.

When making compound chocolates, any fat apart from cocoa butter must be of similar melting point and triglyceride profile. One can also use the method of fractionating the fats which enriches stable triglycerides. In case of using a filling in a chocolate shell, what works is a barrier fat between the filling and the chocolate which can help stop the fat inside the filling or insie the chocolate to migrate to the surfaace.

In the next article we will talk about Sugar Bloom, its causes and some solutions.

We hope the above article has helped you in some way in your chocolate making journey.

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For India- Rs. 2499/-

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Outside India:- USD 39/-

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Tag: chocolate troubleshooting

Blooming in chocolates – Blooms and defects – Part 2

Blooming in Chocolates- Blooms and Defects