Some of the properties associated with quality chocolate are formed during the tempering process, but some researchers felt that more needed to be understood about the science that underpinned the changes that were happening at a molecular level in order to improve control and quality.

Fumitoshi Kaneko, Kiyomi Oonishi, Hidetaka Uehara, and Hironori Hondoh have, in a new scientific paper, examined how crystalline structures of fat molecules change when using a chocolate mold.

The favourable characteristics of quality chocolate include a ‘snap’ when broken and gently melting when held in the hand. The tempering process is required for quality chocolate because of the use of cocoa butter as an ingredient, which has fats comprised of several glycerides of fatty acids, each with different melting points.

When making chocolate it’s important to arrive at a stable form with unified fatty acid crystals that supports a stable structure, but the different fats melt at different temperatures making the melting and reforming a real art form.

The process of controlling the crystallisation process of fat in chocolate is one of the aspects of chocolate making that beginners often find challenging. To understand how the crystaline structures were forming under different conditions, the researchers took a new approach, using a different analysis methodology, specifically a technique called Fourier transform infrared spectroscopy (FTIR), which they combined with attenuated total reflection (ATR).

This gave them insights into the conformity, regularity and orientation of fat components. The researchers discovered that it varies significantly within each bar of chocolate depending on their position. The researchers deduced that the differences can be explained by looking at whether the chocolate was near the mold surface or on the other side. A conclusion supported by the fact that the mid-point between them showed an intermediate characteristic.

The researchers believe the difference may be in the heat transfer from the mold vs from the air, which could explain the more uniform crystalline structures on that side.

Source for this story: American Chemical Society. (2021, May 26). How the mold influences a chocolate bar’s crystalline structure. ScienceDaily. Retrieved June 1, 2021 from

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