Engineers are applying a technique used in crude oil processing to create low-fat chocolate that actually tastes delicious.

Rongjia Tao, a physicist at Temple University, has recently invented a method to produce low-fat chocolate. The viscosity of melted chocolate is an important factor in the chocolate manufacturing process and is kept low, traditionally, by adding cocoa butter. Tao’s method, which utilizes an electric field to decrease the viscosity of chocolate, lowers fat content by up to 20%.


High Fat Content of Chocolate

Cocoa powder, cocoa butter, and sugar are the main ingredients of dark chocolate. This combination needs to be melted down to flow through tubes during the manufacturing process. The melted chocolate is then solidified and wrapped in foil.

The fat in the cocoa butter is important to reduce the thickness of the melted chocolate so that the liquid can easily flow through the tubes. Without enough cocoa butter, the thick chocolate may block the factory pipes.

Therefore, current chocolate manufacturing techniques lead to a high amount of fat — as much as 40%.

This issue has been acknowledged for decades. However, previous solutions have focused on producing low-calorie fats to be used instead of cocoa butter. Unfortunately, these alternative fats are prohibited in most countries. In some countries, the products which use the alternative fats are not even called chocolate; this is due to the fact that cocoa butter is replaced in these products.

The new method introduced by the team at Temple University addresses the aforementioned problem by applying a small electric field to the low-fat chocolate. Since chocolate is one of the most widely-used flavors in the world, the new low-fat chocolate can significantly reduce widespread obesity.


Tao and His Colleagues’ Method

Tao’s method is based on electrorheology which is related to the flow of matter when affected by an electric field. An Electrorheological (ER) fluid is a suspension of non-conductive particles which are electrically active. The viscosity of an ER fluid changes with the applied electric field.

Typically, we can increase the thickness of an ER fluid to that of a gel-like material, depending on the strength of the applied electric field. This phenomenon, which is reversible, happens in a few milliseconds.

Traditional applications of ER, which mainly include fast hydraulic valves, clutches, and braking systems, use an electric field to increase the viscosity of a liquid to a gel-like material. Such applications apply the electric field perpendicular to the flow direction.

However, Tao and his colleagues utilized this method to decrease the viscosity of chocolate. They showed that applying an electric field in the direction of liquid flow leads to small chains of particles which prevent the chocolate from blocking the tubes and effectively decreases the viscosity.


Image courtesy of PNAS via the The Verge.


Tao’s team believes that the new ER method could reduce the viscosity of any liquid. Tao has previously suggested improving the transportation of crude oil by applying an electric field to reduce the viscosity of the fuel. Moreover, he has worked on preventing heart attacks by thinning the viscosity of blood by means of a magnetic field.

Due to these successful experiences, a consulting firm which worked for Mars Inc. called Tao in 2012 and asked him to find a solution to reduce the viscosity of liquid chocolate.

The ER method makes the smooth flow of chocolate possible, even though the fat content of the chocolate had been reduced by up to 20%.


Image courtesy of PNAS via Confectionary News.


According to Tao, fat is not where the chocolate flavor comes from and chocolate’s main flavor is in the cocoa solid. Therefore, there is no difference between the taste of the ordinary chocolate and that of the chocolate produced by the new method. Tao claims that some people find the new chocolate even has a slightly stronger cocoa flavor. Hence, the ER-treated chocolate not only is healthier but also is tastier.

There is convincing evidence that dark chocolate may have significant health benefits. Scientists believe that dark chocolate may significantly enhance cognition. In 2012, The New England Journal of Medicine reported that countries which consume more chocolate are more likely to produce Nobel laureates. Besides, chocolate consumption may lower the risk for heart failure.

Before the ER method was introduced, some of the health benefits of chocolate were offset by its fatty nature. However, the new method, which is expected to be commercially available in one year, leads to a healthier and tastier chocolate.




  • Mr.Beard 2016-07-22

    This is a pretty interesting materials science. Was distracted by the falsity that less fat = healthier.

  • Steve Arar 2016-07-25

    Thanks for the comment.
    Actually, I’m not in the right position to discuss the effects of fat on the health, but considering the attention that is drawn to the above research from many different groups, I can conclude that the fat content of chocolate is harmful.
    Besides, the cocoa butter itself may be less harmful than other fats, but most of the time the fat content of chocolate consists of both the cocoa butter and other fats.