Effect of cocoa bean drying methods on polycyclic aromatic hydrocarbons contamination in cocoa butter

Numerous polycyclic aromatic hydrocarbons (PAHs) are carcinogenic, making their presence in foods and the environment a health concern. This study assessed the contamination and or/ formation of PAHs in cocoa butter as affected by their cocoa bean drying methods. Three major drying methods were evaluated, including full sundrying, full artificial drying and the drying combination of sundrying followed by artificial drying. Result of the study showed that PAHs contamination in cocoa butter originated mostly from smoke contamination during their bean’s drying and small amount intentionally synthesized during fermentation and drying. Longer drying time promoted a higher concentration of PAHs, although still below the maximum limit of 2 ppb. PAHs concentration significantly higher in cocoa butter extracted from whole cocoa bean compared with that extracted from cocoa cotyledon, indicating the contaminant moved from cocoa shell into the bean cotyledon. Uses of artificial dryer with wood as fuel showed a higher risk of contamination compared with the uses of kerosene and industrial diesel oil (IDO). The highest risk of contamination during artificial drying was obtained when there was a leak of gas separator facilitating a contact of firing gas with cocoa beans. Introduction Polycyclic aromatic hydrocarbons (PAHs) are organic compound containing only hydrogen and carbon. Benzo[a]pyrene (BaP) is a PAH that is a pollutant and carcinogen, usually used as marker of the contamination. It can be found in coal tar (after a forest fire), after eruption of volcanoes, in cigarette smoke, and in burnt foods such as coffee. Evidence exists to link benzo[a]pyrane to the formation of lung cancer (IARC, 1987; The European Cocoa Association, 2005). Studies in European countries showed that the main contributors for PAH are smoked fish and meat, cereals and vegetables (DGSANCO SCOOP, 2006). A number of PAHs have been shown to be genotoxic carcinogens. In 2002, the Scientific Committee on Food (SCF) reviewed PAH toxicity. For 15 compounds it concluded that there was clear evidence for their toxicity. In view of the non-threshold effects of genotoxic substances the Committee recommended that the levels of PAH in food should be reduced to as low as reasonably achievable (European Union, 2006). Joint FAO/WHO Expert Committee on Food Additives (JECFA) performed a risk assessment on PAHs, basically agreed with the SCF selection, downgraded one substance from the SCF list, and nominated one further compound for observation in food (JECFA, 2006; European Union, 2006). About 660 different compounds belong to the PAH group of which some show carcinogenic properties (Sander and Wise, 1997). The combined list nominated by either SCF or JECFA would thus comprise of 16 substances. Maximum levels of benzo[a]pyrane, used as a marker for PAH contamination, in a range of foodstuffs are now specified in Commission Regulation (EC) 1881/20061. However, there are some uncertainties in relation to the accuracy of benzo[a]pyrane as a general indicator for overall PAH contamination and the selection of food groups specified in the regulation (European Communities, 2005; European Food Safety Authority, 2008). Scientific Committee on Food, the European Communities (2005) and Standing Committee on Foods (2002) stated that benzo[a]pyrene can be used for marker in the detection of PAH covering benzo[a]anthracene,benzo[b]fluoranthene, benzo[j]fluoranthene,benzo[k]fluoranthene, benzo[g,h,i]-perylene,chrysene,cyclopenta[c,d] pyrene,dibenz[a ,h]anthracene,dibenzo[a ,e] pyrene,dibenzo[a,h]pyrene,dibenzo[a,i]pyrene, dibenzo[a,l]pyrene,indeno[1,2,3-cd] pyrene and 5-methylchrysene. Benzo[a]pyrene and DMBA [7,12dimethylbenz[a]anthracene) were also suggested as effective tumor initiator and perfect carcinogen in a serial research on mice skin (DiGiovanni, 1992; Baer-Dubowska, 1997; EFSA/DATEX/002, 2008).