- spanishchef.net

Spanishchef.net recommends these products

Candy trap: Chocolate candies laced with PAHs

Having overindulged in chocolate and sweets over Christmas, I returned to my desk to find a report that chocolates contain measurable amounts of polycyclic aromatic hydrocarbons, known as PAHs. In fact, chocolate is just one of many food groups that are contaminated with PAHs, so what is the problem? Well, many PAHs are carcinogenic.

PAHs are a group of ubiquitous organic pollutants, which are resistant to degradation and have very long lifetimes in the environment. They have been added to the list of persistent organic pollutants (POPs) defined by the UN Environment Council and they bioaccumulate in animals and humans, so the threat to health is also persistent.

The major sources of PAHs are fuel combustion, industrial processes and road transport but the heightened awareness of the potential health problems has contributed to their reduced emissions in recent years. For instance, PAH emissions have fallen by more than 60% in the countries belonging to the European Environment Agency between 1990 and 2007.

However, PAHs are also formed during the production of foodstuffs by drying, smoking, grilling, roasting and frying and it is far more difficult to eradicate these sources. One study in the EU consistently found PAHs in cocoa butter, dried tea, barbequed meat and chocolate, illustrating the variety of food types affected.

In practice, limited data has been reported on the occurrence of PAHs in chocolate as studies have been few and far between. In particular, analysis of the priority PAHs, those compounds regarded as the most carcinogenic, has not been carried out in chocolate candies, according to a team of Indian researchers led by Devendra Patel from the CSIR-Indian Inst. of Toxicology Research at Lucknow.

Now, Patel has developed a simple procedure for the analysis of 16 priority PAHs by HPLC, which has been reported in the Journal of Food Science.

Chromatography for candy extracts

The chocolate candies were homogenised with water and extracted with hexane followed by de-emulsification with ethanol. The extract was cleaned up on a silica gel column to remove interfering compounds from the chocolate matrix and redissolved in acetonitrile for quantification of the PAHs by HPLC.

The PAHs were separated on a C₁₈ column with an isocratic mobile phase of aqueous acetonitrile and UV detection at 254 nm. The compounds were eluted within 20 minutes and 10 of the 16 PAHs were well separated in the chromatogram.

However, separation was not complete with three pairs of PAHs coeluting, so these compounds were measured together. They were fluorene and acenaphthalene, benzo[a]anthracene and chrysene, and indeno[1,2,3-c,d]pyrene and benzo[g,h,i]perylene. In case of any confusion over the identities of the 16 individual PAHS, they were confirmed by GC/MS.

The detection limits of the PAHs ranged from 0.3-4 ng/g and the recoveries and other analytical criteria were found to be satisfactory, so the team applied the optimised method to the analysis of PAHs in 25 commercial chocolate candies bought in a local market.

Sweet but sour

Every chocolate tested contained PAHS, with at least four found in each single sample. The total amounts fell in the range 2.70-235.91 ng/g with a mean concentration of 67.62 ng/g. For most of the samples, the lower-molecular-weight PAHs were more abundant than the higher-molecular-weight types.

The most carcinogenic PAH, benzo[a]pyrene, was found in 23 of the 25 candies, in the range 0.35-12.76 ng/g. In two samples, the level exceeded the official EU regulatory limit of 5 ng/g for this PAH in cocoa butter.

Patel pointed out that the amounts were relatively high compared with previously reported values for PAHs in chocolate products and suggested that more effective measures should be implemented to reduce PAH contamination in chocolate candies in the future.

The HPLC method developed here, which enables the simultaneous analysis of 16 PAHs, is a relatively simple, rapid and cost effective procedure which could be applied to the routine analysis and quality control of PAHs in chocolate candy.

If you liked this, you may also like…

Choc-a-bloc with flavour enhancers [Ezine]
GC-MS detection of chiral markers in cocoa beans of different quality and geographic origin [Journal Highlight]

Article by Steve Down

Read more about Steve Down and our other columnists

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

Chocolate News Page
Chocolate with Bill & Sheila
_____________________________________________________________________
If you require a high quality printout of this article, just click on the printer symbol next to ’Share and enjoy’, and we will do the rest. This site is hosted by (click on the graphic for more information) chocolate

Return from chocolate to Home Page

If you want to increase your site popularity and gain thousands of visitors – check out these sites THEY ARE FREE. Spanishchef more than doubled its ‘New Visitors’ last month simply by signing up to these sites: