Chocolate makers could see savings from new research that sets out to tackle the common problem of fat bloom, an unsightly white powdery film that forms on the outside of chocolate, writes Lindsey Partos.
Fat bloom is a common problem in the confectionery industry, and can cause some product losses, not because there is a contamination or specific quality issue but largely because the visual characteristics become unacceptable to the consumer.
"The costs are negligible, and fat bloom is largely linked to the quality of the distribution chain. When chocolate is stored properly fat bloom can be avoided," a spokesperson for Swiss confectionery giant Nestlé told FoodNavigator.com.
The bloom arises from changes in the fat structure in the chocolate and is caused by a variety of factors, including poor tempering of the chocolate, incorrect cooling methods and the presence of soft fats in the centres of chocolates. Warm storage conditions, and the addition of fats that are incompatible with cocoa butter, can also cause the bloom.
Researchers at the University of Amsterdam have identified the crystal structure of one of the three main triglycerides that make up chocolate butter. The triglyceride, called SOS, is a cis-mono-unsaturated type and represents one quarter of the chocolate butter. They suggest their discovery will help in better understanding the melting behaviour of cocoa butter and better controlling the production process.
“This work is expected to be highly relevant to confectionery research and industry and the first step to a better understanding of the mechanism of the fat bloom phenomenon at the molecular level,” said Dr. René Peschar.
The researchers used ESRF (European Synchrotron Radiation Facility) synchrotron light to collect ‘superior data' from which they determined this structure using the X-ray powder diffraction technique.
Fat bloom caused by temperature damage is more or less under control in Europe, where manufacturers know that their chocolate needs to be stored at a constant temperature, but migration fat bloom is a global problem, and one which has seen confectionery firms invest in R&D to come up with a raft of solutions.
Although taste is not affected by this bloom – as with others - the ‘mouth-feel' of the product might change, melting differently in the mouth due to the higher melting point. Swiss chocolate supplier Barry Callebaut is working on research, with the University of Ghent, that could lead to cost savings for chocolate makers.
“We are focusing our research on designing a predictive model that could indicate to makers whether fat bloom will occur in a said product batch,” said Alex Landuyt, head of R&D Europe for Barry Callebaut.
At the moment, firms will only detect the fat bloom when its too late, 24 to 36 months after the chocolate has been produced.
In a competitive market, players want to eradicate, or minimise, any negative factors that could harm their sales, so while the white powdery film does not affect taste, it might nonethless impact sales. Should the fat bloom arise, manufacturers might be obliged to sell their product at a lower price, or re-melt the chocolate to then re-use in further formulations.
“2005 is our goal for defining the predictive model. Initially a lab scale installation, afterwards we will go to industrial scale, to service our customers,” added Landuyt, whose firm processes some 520,000 tonnes of cocoa annually in a market of 3.1 million tonnes .
Manufacturers currently use traditional methods to combat bloom. For example, one key technique legally acceptable the world over is the addition of full cream fat powder to milk chocolate to delay the migration of fat bloom. In dark chocolate – which only contains cocoa butter – 3 to 4 per cent butter oil can lengthen the shelf life.
“Tempering is also a very important way to delay the onset. Well tempered and cooled chocolate will stabilise the structure and mean no re-crystallisation,” explained Landuyt.
Full findings of the University of Amsterdam study, ‘Crystal Structures of 1,3-Distearoyl-2-oleoylglycerol and Cocoa Butter in the â(V) Phase Reveal the Driving Force Behind the Occurrence of Fat Bloom on Chocolate', are published in the September issue of the Journal of Physical Chemistry B