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Keeping The Seductive, Shiny Brown Surface Of Fresh Chocolate As It Ages

Date:
June 13, 2008
Source:
Royal Society of Chemistry
Summary:
What do George Clooney and old chocolate have in common? Both are still delicious but have greyed with age -- and while this certainly hasn't damaged the image of the former ER star, it does detract from the appeal of the mocha ambrosia, despite being perfectly safe to eat.
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As the escaping "fat blooms" recrystallise they scatter light, giving old chocolate its characteristic dull white appearance.
Credit: Image courtesy of Royal Society of Chemistry

What do George Clooney and old chocolate have in common? Both are still delicious but have greyed with age – and while this certainly hasn’t damaged the image of the former ER star, it does detract from the appeal of the mocha ambrosia, despite being perfectly safe to eat.

To help maintain that seductive, shiny brown surface, scientists from Canada and Sweden have shown that understanding chocolate’s microstructure is key to stopping those unappetising looking, and sounding, “fat blooms”.

Fat blooms occur because chocolate is extremely sensitive to temperature – just a 2°C fluctuation will cause the cocoa butter to melt, then recrystallise, forming needle-like structures that scatter light, giving a dull appearance.

The team, led by Dérick Rousseau at Ryerson University, Canada, studied the surface of chocolate as it aged using a scanning electron microscope (SEM), which fires electrons at the surface and measures the electrons knocked back from it to build a picture of the surface with very high resolution.

They found that where the chocolate surface was rough, blooms were far more likely to form. Rousseau says that if manufacturers were to minimise the amount of surface imperfections, this would be a good way to reduce blooms.

Watch out if you like the strawberry cream, too – the team tested filled chocolates and found they were even more susceptible to the blooms. The liquid-state fat in the filling migrates through the chocolate, accelerating bloom formation and ultimately making the chocolate very soft.

Nigel Sanders, senior research scientist at Cadbury in Toronto, Canada, says that “as an industry, we haven’t got to the bottom of what tools we have to stop bloom formation from happening.”

“Companies as large as Cadbury do their own research – but never gets published,” adds Sanders. “It’s nice to see an academic study that helps the whole industry, and isn’t just for the big boys.”


Story Source:

The above post is reprinted from materials provided by Royal Society of Chemistry. Note: Materials may be edited for content and length.


Journal Reference:

  1. Rousseau and Smith. Microstructure of fat bloom development in plain and filled chocolate confections. Soft Matter, 2008 DOI: 10.1039/b718066g

Cite This Page:

Royal Society of Chemistry. "Keeping The Seductive, Shiny Brown Surface Of Fresh Chocolate As It Ages." ScienceDaily. ScienceDaily, 13 June 2008. <www.sciencedaily.com/releases/2008/06/080610191040.htm>.
Royal Society of Chemistry. (2008, June 13). Keeping The Seductive, Shiny Brown Surface Of Fresh Chocolate As It Ages. ScienceDaily. Retrieved July 4, 2015 from www.sciencedaily.com/releases/2008/06/080610191040.htm
Royal Society of Chemistry. "Keeping The Seductive, Shiny Brown Surface Of Fresh Chocolate As It Ages." ScienceDaily. www.sciencedaily.com/releases/2008/06/080610191040.htm (accessed July 4, 2015).

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