How Temple University in Philadelphia and Mars Chocolate reduced Fat in Chocolate by 40 Percent

Chocolate as we all know is good for you in many ways. But processing Chocolate into Chocolate bars has always been difficult dye its high fat content.

Physicists from the Temple University in Philadelphia have discovered that they can use electric fields to change the viscosity of Chocolate as noted in the article “This bizarre method might make Chocolate healthier — and tastier”, published June 20, 2016, by Ali Sundermier, Business Insider.

The research which was published in the PNAS (Proceedings of National Academy of Sciences), has already being patented at the US Patent and Trademark Office and was actually funded by Mars Chocolate.

Their research basically indicates that once an electric field is applied parallel to the flowing liquid Chocolate in the direction of its flow, they can change the microstructure of the particles inside the Chocolate.

This technique is basically a practical application of Electrorheology, the field of research concerned with the deformation and flow of matter when affected by electricity as explained in the article “Lower­fat Chocolate is now possible thanks to electrical engineering”, published June 20, 2016 by Vlad Savov, The Verge.

This electric field requires high voltage power supply to generate the electric field. The cocoa particles begin to form short chain polymers, effectively making them as viscous as liquid oil and reducing the amount of fat in the Chocolate.

So why is this discovery by the researcher at Temple University in Philadelphia so important to the food processing industry?

How to make Chocolate Fat Free - How MRJ density and Intrinsic viscosity affect Cocoa Butter  

This developement is important as Chocolate is 40% fat by volume as a solid or liquid. When processing Chocolate, it's powdered and melted under low vacuum into a liquid that consists of the following components:

1.      Cocoa

2.      Sugar

3.      Milk solids

4.      Cocoa butter

5.      Liquid Fat molecules

Liquid Chocolate causes the pipes to clog up during the processing of Chocolate into solid bars as noted in the article “Giving low­fat Chocolate a jolt allows it to flow”, published June 27, 2016 by Shalini Saxena, ArsTechnica.

Given the nature of Chocolate, it’s clearly a suspension with its properties dependent on the shape of the particles:

1.      MRJ density

2.      Intrinsic viscosity

The MRJ density is the maximally random jammed density, which describes the highest three-dimensional packing density achieved by particles in a suspension. The Intrinsic viscosity is the particles contribution to the liquid viscosity.

An example of how these properties affect the property of suspensions can be seen from considering perfectly spherical properties. Particles that are purely spherical have a MRJ density is approximately 64% while the intrinsic viscosity is 2.5.

The Physicists from the Temple University in Philadelphia used optical microscopes to visually inspect and measure the cocoa particles and determined that they were spherical with a diameter of 2 micrometers.

That mean that fat had to be 64% of the space, based on the MRJ, otherwise if the fat was removed, the MRJ would spike and the particles would be in their maximum packed state, resulting in the pipes becoming blocked during Chocolate processing.

How to make Chocolate Fat Free – Practical application of Electrorheology 

The researcher then realized that in order to remove the need to add cocoa butter to increase viscosity, they have to do the following:

1.      Reduce the Intrinsic viscosity of the Chocolate

2.      Increase the MRJ density of the Chocolate

The application of an electric field did the trick, as the cocoa particles, which are organic covalently bonded molecules, are polar. These solids suspended in the Chocolate would aggregate into short chain particles along the direction of the electric field to conduct the applied charge.

This disrupts the microstructure of the Chocolate by making all the particle have similar rotational symmetry, thereby achieving the desire changes in Intrinsic viscosity and MRJ density of the Chocolate.

Food processors have to add cocoa butter to increase the fat content and make the Chocolate easier to process. This has huge implications for the Chocolate industry, as it means that they can make low fat Chocolate, thereby making Chocolate healthier and thus allow Mars Chocolate widen their market to the Health Foods Sector with low Fat Chocolate.

It will also make more efficient use of Chocolate, being as we're approaching a major Chocolate shortage in 2020 as predicted in my blog article entitled “Why Chocolate Shortage in 2020 as Chinese, Indian and American addiction Inflates Price of Cocoa”.

More interestingly, this technique may also have implications for altering the structure of other solid foods that exist as liquids at high temperatures during food processing. Food processors can now use less cocoa butter and thereby reduce the fat content to 28% while maintaining the taste of Chocolate.