Topic:

Coffee is one of the most traded commodities world-wide and among the most widely consumed beverages. Coffee aroma teases and pleases us; coffee boosts us in the morning and saves the day when energy levels start sagging. Experts further attest that moderate coffee consumption brings health benefits and that coffee should rightly be clas-sified as a functional food. But in our mad rush for coffee, we should never overlook that stringent quality assurance criteria must be met for this rather complex product. These include microbiological tests, residual humidity, sensory assessment, and determination of organic as well as inorganic contaminants. A few specialized chromatography-based analyses are also required. These include determination of the coffee type used, whether the more expensive Coffea arabica (Arabica) or the more abundant Coffea canephora (Ro-busta). Further, the caffeine level is important, especially for decaffeinated coffee prod-ucts. Given that crop protectants are widely used, the levels of pesticide residues must also be determined. And, finally, the levels of mycotoxins, such as Ochratoxin A, must be determined since storage in hot and humid climes is conducive to their formation. But, as has become clear in recent years, there is still more to do: Acrylamide is formed during coffee roasting, when amino acids react with reducing sugars. 

The challenge:

Acrylamide (2-Propenamide, C3H5NO) has been proven to be both geno-toxic and carcinogenic in animal experiments. Still, we are inevitably exposed to acryla-mide. Whenever food is baked, toasted, fried, deep fried, or roasted, acrylamide is formed as a byproduct. During coffee roasting, the amount of acrylamide formed can certainly be influenced, but it cannot be eliminated. This means that the quality assurance process must include monitoring of acrylamide levels. 

The solution:

Determining acrylamide levels in coffee is not trivial and the sheer number of samples to be analyzed is daunting. This means that there is demand for methods that are efficient, rugged and sensitive. Acrylamide is a highly polar compound that is deter-mined by LC-MS/MS. To determine acrylamide in ground coffee and cereal coffee, the ma-trix must first be removed using SPE cleanup. Application experts from Macherey-Nagel and GERSTEL formed a team to determine how the task can be performed in the most effi-cient manner. 

The conclusion:

The result of the joint development project was published in GERSTEL AppNote 238. The SPE cleanup step and sample introduction can conveniently be automated using the GER-STEL MultiPurpose Sampler (MPS) fitted with SPE option. Chromabond ABC18 cartridges are used. Validation data show that the method delivers high accuracy and good rugged-ness. The only exception was cereal coffee at very low acrylamide levels from 50 to 300 µg/kg. However, these are not very relevant given that  the EU guidelines for cereal coffee stipulate maximum levels of 2000 µg/kg. By the way, the GERSTEL MPS can be fitted with additional modules such as a vortex-like agitator, a centrifuge, and an ultrasound bath, enabling the system to perform the workflow defined in DIN EN ISO 18862 in a completely automated and highly efficient process. (GD)