Mineral oil contamination along the cocoa supply chain: impact of storage and transportation in jute bags and assessment of contamination transfer into cocoa powder and cocoa butter

Abstract

On-line high-performance liquid chromatography (HPLC) - gas chromatography (GC) analysis of 28 whole cocoa beans before and after transport in jute bags contaminated with mineral oil hydrocarbons (MOH) showed that average saturated hydrocarbons (MOSH) increased from 0.9 to 9.6 mg/kg, with aromatic hydrocarbons (MOAH) reaching 2.3 mg/kg. On average 40 % of the MOH migrated into whole beans reached the shelled beans, with a cut-off at n-C₂₅. Post-transport jute bags contained diverse mixtures of MOH, varying in both amount and molecular weight distribution, as well as MOAH percentage. It was estimated that MOAH n-C_10-25 exceeding 220 mg/kg in new jute bags expose whole beans to contamination above 2 mg/kg. GC × GC coupled to single quadrupole mass spectrometry (MS) proved effective for detailed MOH characterization. Throughout the supply chain, MOH contamination was transferred to cocoa mass, sometimes influenced by external lubricant inputs, and partitioned into cocoa butter and powder according to fat content.

Keywords: Cocoa bean contamination; Jute bags; Mineral oil aromatic hydrocarbons (MOAH); Mineral oil saturated hydrocarbons (MOSH); Multidimensional gas chromatography (GC × GC); On-line HPLC-GC.