Limonene is a component which is naturally present in essential oils of citrus fruits, according to the main author of the study Annelien Rigolle, a science faculty member at the University of Leuven, specializing in fat crystallization.
“Limonene was not added for its health benefits, but for its viscosity reducing effects,” she added.
FBC Chemical Crop, which is a Pennsylvania-based limonene distributor did not immediately respond to ConfectioneryNews’ questions regarding limonene’s average market price in the US. However, researchers of the study bought 500ml (16 ounces) limonene for €75 ($84.75) from Sigma-Aldrich.
Unnecessary to temper the chocolate to obtain the desired bV polymorph
Previous research has shown limonene has a softening effect on chocolate, so the component is usually added to reduce the viscosity of chocolate, Rigolle said. “[Limonene] will also have an effect on the crystallization behaviour of chocolate and we examined the effect of different concentrations limonene and the effect of the crystallization temperature.”
It turns out that limonene accelerates the crystallization process and also the transition to polymorph bV, which is the typical desired crystal structure in chocolate at 17°C, Rigolle said.
“We saw that this bV form was formed within 70 minutes under static conditions, while otherwise this transition occurs in a time span of a few days under these conditions. This could mean that it is unnecessary to temper the chocolate in order to obtain the desired bV polymorph.”
In contrast, at a higher crystallization temperature of 20°C (68 Fahrenheit), limonene delayed the crystallization process by means of X-ray diffraction, Rigolle added.
There is no single effect of limonene
Researchers used cocoa butter, the main ingredient of chocolate as the matrix for the study, according to Rigolle. But she said it could be interesting to validate the study results with chocolate itself. In the meantime, the experiment was conducted under isothermal conditions, so results might vary if researchers use industrial process conditions instead.
Asked what the biggest takeaway for chocolate manufacturers from the study is, Rigolle said the effect of limonene clearly depends on the crystallization temperature used and also on the concentration applied.
“There is no single effect of limonene,” she said. “Furthermore, you can’t just add a component to adjust the viscosity of reduced fat chocolate. This component will also alter the crystallization behaviour, so you have to search for a compromise between viscosity and crystallization behavior.”
Journal of Agricultural and Food Chemistry
Publication Date: April, 12 2016
‘Isothermal crystallization behavior of cocoa butter at 17°C and 20°C with and without limonene’
Authors: Annelien Rigolle, Bart Goderis, Koen Van Den Abeele, and Imogen Foubert