Researchers from the University of Birmingham produced stable cocoa butter water-in-oil emulsions containing up to 60 per cent water by mass, which did not cream on storage.
Additionally, the cocoa butter in the emulsions was found to be in the form that “consumers find the most attractive, as it melts between 32 and 34 °C”, according to findings to be published in the November issue of the Journal of Food Engineering.
“Results [of our study] suggest low-fat chocolate formulations using this route may be feasible,” wrote the researchers, led by Dr Phil Cox.
In an email to FoodNavigator, Dr Cox stated: “We have just patented an extension to the preliminary work and are in discussion with companies.”
The issue of health is no longer a marginal topic for the food industry but wholly mainstream, and it finds confectioners, biscuit and cake makers seeking to juxtapose today's consumer desire for indulgence with their desire for foods with a healthy profile.
According to a recent study from the US, only 5 per cent of American children between 6 and 11 were overweight before 1980, but 25 years later this number had risen to 19 per cent. Similar increases have been reported in Europe, with the International Association for the Study of Obesity estimating in 2006 that the number of obese school age children in Europe increased by almost 50 per cents since the late 1990s.
“As chocolate is notoriously high in calories (a gram of fat contains approximately nine calories), it may be detrimental to maintaining a healthy weight,” explained the researchers. “There may thus be a gap in the market as low-fat chocolates with desirable taste and texture are currently not readily available.”
In order to fill this gap, the Birmingham-based researchers prepared water-in-oil emulsions, meaning a continuous phase of cocoa butter with a dispersed water phase. Dr Cox and his co-workers used polyglycerol polyricinoleate (PGPR, Kerry Bio-Science) and soy lecithin (Sigma) as emulsifiers, both of which are extensively used in current commercial chocolate manufacture.
Emulsifiers are used by food makers to reduce the surface tension between two immiscible phases at their interface - such as two liquids, a liquid and a gas, or a liquid and a solid - allowing them to mix.
Using a ‘margarine line’, which is a continuous process, or a high-shear mixer, the researchers prepared emulsions with droplets ranging from one to 10 micrometres in size.
“It is thought that the bench scale margarine line is a better method of creating a cocoa butter emulsion,” wrote the researchers. “It is likely to be more successful for creating an emulsion of the correct polymorphic form as temperature and shear can be controlled with more precision. […] It is also a better method for creating emulsions with a small droplet size.
“Furthermore, it is likely to be more appropriate for large-scale industrial production as it is a continuous process,” they added.
Source: Journal of Food Engineering
November 2009, Volume 95, Issue 1, Pages 172-178, doi: 10.1016/j.jfoodeng.2009.04.026
“Development and characterisation of tempered cocoa butter emulsions containing up to 60% water”
Authors: J.E. Norton, P.J. Fryer, J. Parkinson, P.W. Cox