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.
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