Why does chocolate turn white in the refrigerator?

Friday 9 May 2025 09:05

You open the fridge after a long day, looking for that piece of chocolate you left "in safekeeping" so as not to give in to temptation too soon. You take it out of the wrapper with some ceremony, ready to give yourself a little treat, and suddenly... you see it. That whitish layer on the surface that looks like chalk, as if the chocolate had filled with dust or started to spoil.

The doubt sets in: do I eat it the same way? Is it in bad shape? Why does it look like that?

This phenomenon is more common than it seems and is often disconcerting. It doesn't matter whether it's a high-purity bar or a milk chocolate: when chocolate is stored in inappropriate conditions (for example, in the refrigerator), it can develop that white film that generates a certain rejection. What happened? Is it mold? Is it out of date? Spoiler: no, it is not. What you see is a natural physico-chemical process, well known and not related to fungi or food safety.

What is chocolate bloom?

The English term bloom which can be translated as "bloom" or "efflorescence", describes the phenomenon whereby a whitish or grayish layer appears on the surface of chocolate. There are two main types:

Fat bloom: occurs when cocoa butter destabilizes and migrates to the surface. When it crystallizes, it forms a visible film. It is usually caused by temperature variations or poor tempering during chocolate processing.

Sugar bloom: occurs when chocolate comes into contact with moisture. The water dissolves part of the sugars on the surface and, as they evaporate, they recrystallize to form a granular, opaque layer.

Both phenomena are purely aesthetic, although they can influence the texture and, to a lesser extent, the flavor of the product.

Why does this happen when refrigerating chocolate?

Storing chocolate in the refrigerator exposes the product to humidity and temperature changes that promote both fat bloom and sugar bloom. Condensation on the surface can initiate sugar bloom, while low temperatures and temperature fluctuations favor the instability of fat crystals, leading to fat bloom.

In addition, cocoa butter has a polymorphic crystalline structure; that is, it has several forms of crystallization, not all of which are stable. The most desirable form (known as the V-form) gives a glossy finish and a good texture, but it can transform if the cold chain is broken.

Does this affect the quality of the chocolate?

From a food safety point of view, bloom poses no risk. Chocolate with bloom is not spoiled or unsafe for consumption.

However, its sensory quality may be affected. The texture becomes rougher or more brittle, the appearance loses luster and the flavor may seem somewhat less intense or more rancid, especially if it has been stored for a long time or in unsuitable conditions.

How to prevent the appearance of bloom?

Although we often resort to the refrigerator to preserve chocolate, this well-intentioned gesture is often the cause of the problem. Humidity, cold and sudden changes in temperature favor the appearance of this unattractive whitish layer.

The best way to avoid this is to store it in a cool, dry and dark place, where the temperature remains stable, between 59 and 68°F (15 and 20 °C). If the heat gets too hot and there is no choice but to use the refrigerator, it should be stored in an airtight container with some absorbent paper inside, and wait for it to return to room temperature before opening it. This avoids condensation, the main cause of sugar bloom.

It is also important to protect it from intense odors, since chocolate easily absorbs foreign aromas that can alter its flavor.

And you, has it happened to you?

Have you ever found yourself with "bloomed" chocolate, did you know it was not spoiled, do you have a trick to preserve it better? Share your experiences and tips in the comments.

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Patricia

Passionate about cooking and good food, my life revolves around carefully chosen words and wooden spoons. Responsible, yet forgetful. I am a journalist and writer with years of experience, and I found my ideal corner in France, where I work as a writer for Petitchef. I love bœuf bourguignon, but I miss my mother's salmorejo. Here, I combine my love for writing and delicious flavors to share recipes and kitchen stories that I hope will inspire you. I like my tortilla with onions and slightly undercooked :)