Organic petrology in the service of public awareness: How safe are barbeque briquettes?

Charcoal has been an important source of energy for centuries and remains till today. Currently charcoal is used, mostly for cooking purposes, in the form of lumps, as well as processed in the form of briquettes. Charcoal briquettes are formed by compressing pyrolyzed biomass (charcoal) particles together with a suitable binder, such as starch mixed with water. Based on the European standard EN 1860-2 (2005) the moisture and the ash yield for the dry charcoal briquettes shall not be above 8 wt% and 18 wt%, respectively, and the total of all detected inadmissible additions should not exceed 1 vol%. The main purpose of this study is to examine the quality of charcoal briquettes from the Greek market. Nine samples were purchased from various vendors in Patras and examined according to the EN 1860-2 (2005) standard. To assess their quality, incident light microscopy is applied to identify the pyrolyzed material and the range of impurities, including raw biomass, mineral matter, plastic, metallic artifact, oxidized metallic artifact, particles of coal origin, etc. The petrographic analysis reveals that the content of impurities exceeds 1 vol% and that four (out of the nine) samples consist almost exclusively of coal particles. Considering the above and the public health hazards that are posed by grill fuel of subpar quality, the need for effective and reliable quality control methods is urgent. The petrographic analysis of charcoal briquettes seems to be the most appropriate technique.