A new study carried out at Germany’s largest particle accelerator center offered new insights into the quality of the world’s most beloved sweet indulgence – chocolate. German scientists wanted to learn the cause behind fat bloom that occasionally appears on the surface of the sweet product.
Svenja Reinke, co-author of the study and researcher at the Hamburg University of Technology (TUHH), explained that although a piece of chocolate covered with the disgraceful white layer is perfectly edible, food industry experiences losses of millions of dollars because consumers reject the products or file complaints.
The findings of the study were published in the American Chemical Society’s journal Applied Materials and Interfaces. The study was partially funded by Nestlé.
Reinke said that fat bloom is caused by cocoa butter and other fats that are at some point in liquid state but eventually crystallize at the surface of chocolate. According to the research team, the process usually occurs when liquid chocolate suddenly cools down. Nevertheless, chocolate held at room temperature can also form fat blooms due to cocoa butter content.
Moreover, if the chocolate contains other ingredients or liquid fillings, the process may be accelerated. Also, a high room temperature and a prolonged storage time highly contribute to the deterioration of the quality of chocolate through the pesky white coloration.
Usually, consumers who see fat blooms on their chocolate bars think that the product is either spoiled or old. Stefan Palzer, a researcher from Nestlé, said that fat bloom does not spoil chocolate or its quality. Despite this, many consumers choose to complain about what can be only qualified as “a quality defect.”
While trying to get a closer look at the underpinnings of the process, German researchers used PETRA III one of the world’s most powerful source of x-ray radiation on samples of different types of chocolate. They first analyzed the main ingredients of the sweet product including cocoa, milk powder, sugar and cocoa butter.
But before x-raying them, researchers ground chocolate samples into fine powder. Stefan Heinrich, the lead author of the study and TUHH researcher, explained that PETRA III allowed the team to observe the process on a nanometer scale.
Later researchers also analyzed the migration of fats within chocolate. For this purpose, they poured a few drops of sun flower oil on the samples. Scientists noted that chocolate is very porous so it absorbed the liquid fat in a matter of seconds. But they also observed that liquid fat influenced chocolate’s internal structure by dissolving crystals of other liquid fats and making chocolate a lot softer. In return, the migration of fats was significantly accelerated.
The findings of this study are consistent with previous studies aimed at helping food companies to better chocolate. Researchers reached a consensus that fat bloom is linked to chocolate’s crystalline structure. But the novelty of the study consists in the accuracy of the observations.
Researchers argued that their experiment provided the sharpest view on the dynamic mechanisms behind the fat bloom occurrence by observing real time structural changes down to a scale of a few nanometers.
Moreover, the new study will help chocolatiers better understand the process and find new technological means of counteracting it.
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