Food Additive Limonene Smooths The Texture Of Low-Fat Chocolate, Scientists Find

chocolates
When limonene is added to reduced-fat chocolate, it improves both texture and melt due to its effect on crystallization. AFP, Getty Images

Every chocolate lover knows a low-fat version of their favorite sweet is simply an abomination. Not only does it lack the right texture, it also doesn’t melt the way it should. Both these qualities are improved when limonene is added to reduced-fat versions of the confection, yet until now researchers have not known why. A new study explores the process and unmasks the mystery.

Is it ridiculous to ask chocolate makers to leave what works well enough alone? Probably. After all, the delicious sweet is simply the result of a recipe and we all know how enterprising chefs (and food scientists) like to tinker with their recipes. Still, it can be argued that reduced-fat chocolate is a bad idea, not only in terms of taste and quality, but also because it may not be as health-promoting as people presume.

Take a look at the results of a recent study of low-fat dairy. Tufts University researchers found people who eat full-fat dairy products are less likely to develop diabetes than those who grimly consume low-fat (low-pleasure) dairy alternatives. In fact, study participants with the highest levels of dairy fat in their blood had up to a 46 percent lower risk of developing diabetes over the 15-year research period compared to those who had the lowest levels of dairy fats in their blood. And though this was a study of milk, not chocolate, it still indicates that low-fat does not automatically boost the healthiness of a product.

Temper & Texture

With regard to reducing fat in chocolate, the deed has already been done with many versions already on the market. Still, sweet lovers have noticed some versions are smoother and softer than others. In fact, the additive limonene appears to be the game-changer. Limonene, a major constituent in several citrus oils, including orange, lemon, mandarin, lime, and grapefruit, has a citrus fragrance and is widely used as a flavor and fragrance additive in perfumes, soaps, foods (including ice cream and candy), chewing gum, and beverages.

To understand why this common additive made a better low-fat chocolate product, a team of researchers from KU Leuven in Belgium began an investigation. Specifically, Dr. Annelien Rigolle and her colleagues isolated a single step in the recipe. They focused on the crystallization of cocoa butter, which undergoes several important transformations at different times and temperatures.

Comparing crystallization at 63 and 68 degrees, they used various technologies, including X-ray diffraction, to examine the changes cocoa butter underwent at the moment limonene was added. They discovered that adding limonene accelerated cocoa butter crystallization at the lower temperature but inhibited cocoa butter crystallization at the higher temperature. This must be taken into account, then, to correctly temper the chocolate — a sophisticated temperature schedule that controls the crystallization process and creates the desired texture. Adding different concentrations of the additive also affected crystallization in unique ways.

Based on these results, Rigolle and her colleagues say both the amount of limonene and the temperature of the cocoa mix ultimately influence how smooth and melting a batch of reduced-fat chocolate will be. Though purists may quibble, low-fat chocolate is already a reality, one that food scientists will continue to tinker with and perfect.

Source: Rigolle A, Goderis B, van den Abeele K, Foubert I. Isothermal Crystallization Behavior of Cocoa Butter at 17 and 20 °C with and without Limonene. J. Agric. Food Chem. 2016.

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