What Does Dark Chocolate Actually Smell Like? - Chromatography Sniffs It Out
Jun 14 2019
Let’s face it - we can be on the strictest of diets, but, when offered a piece of chocolate many of us find it hard to resist. Milk, dark, organic, white, flavoured and natural chocolate is all consumed with delight. But chocolate has a long history and we don’t yet know all of its secrets. Whilst milk chocolate is undoubtedly the most eaten type of chocolate in the UK - dark chocolate is gaining ground as its high cocoa content is believed to have health benefits. A recent paper published in the Journal of Agricultural and Food Chemistry has described work carried out to analyse the overall aroma in dark chocolate - and gas chromatography was the main technique used.
Cocoa beans, mass and butter
Cocoa and chocolate are one of the most consumed luxury foods - in West European countries we eat an average of 9 kg per person per year. That is a lot of chocolate bars. We focus on the taste, smell and appearance of chocolate, particularly at the higher end of the market when we are eating dark chocolate that is unadorned by nougat, honeycomb or nuts.
Chocolate is a relatively simple product to make. First, cocoa beans are dried, fermented and roasted to make cocoa mass, the main raw material for chocolate. This is then mixed with cocoa butter, sugar and smaller additives to make the chocolate we all love. One of the main attributes of chocolate - and indeed, in most foods - are the volatile aroma molecules that we sense when we eat a piece of chocolate.
It’s a mix of all the elements
Previous work has been carried out on odorants in milk chocolate and cocoa mass and has identified 44 key odorants in milk chocolate, 37 in cocoa mass and 24 in cocoa powder. These odorants were identified by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O). GC is a versatile tool for analysing volatile samples as discussed in this article, Gas Chromatography - Vacuum Ultraviolet Spectroscopy: A Versatile Tool for Analysis of Gasoline and Jet Fuels.
The researchers behind the study mentioned above sought to sniff out the chemicals behind dark chocolates aroma. Individual elements combine to give the overall odour of a food - and in this case the German scientists found almost 70 different aroma producing chemicals using GC-O and GC-MS. Of these, almost 30 were present at levels high enough for us to smell. They managed to recreate dark chocolates aroma by combining the identified elements in the correct ratio.
They identified compounds that individually smelt of vinegar, sweaty cheese, baked apples and a goat like smell. But combined, these elements gave the chocolates their distinctive aromas - which play a large role in how we taste and perceive foods.
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