Take a look in your shopping basket next time you are waiting at the check-out, what are your foods wrapped in? Sure, you don’t eat the packaging, but that doesn’t mean that chemicals in that packaging aren’t transferred to the products that you are eating. Think of that nasty plastic taste you get from some water bottles, or the cardboardy taste from some fast-food containers. Equally, your products may be losing some of their own chemicals into and out through the packaging. If you’ve ever stuck your groceries in a cupboard next to a cardboard box of washing powder, or shared a car with even the best wrapped piece of smoked fish or smelly cheese you’ll know what I’m talking about.
Whilst we can detect some contaminants by their taste or aroma, not all contaminants can be detected by our senses. One such group are the mineral oil-based chemicals, MOSH and MOAH, that are attracting growing interest in the food analysis fields. They have been linked to potentially carcinogenic substances and consequently, it is important that analysts can identify and quantify these substances in food and packaging to enable effective preventative strategies to be developed.
We spoke to Professor Erich Leitner, a leading expert on food quality at the Graz University of Technology in Austria about the problems that food contact materials present, and the strategies he and his team are developing to aid detection and prevention.
Karen Steward (KS): What got you interested in food contact materials and packaging? Why is it important and what are the possible implications to food safety?
Erich Leitner (EL): Initially I started my analytical career in the field of environmental organic trace analysis. Over the years my focus switched to food analysis. Here we investigated flavor and off flavor compounds in food. This is exactly the point where food contact materials start to play an important role due to the possible interactions with the packed goods. If you are looking at the production and sales figures, food contact materials based on polymers or on paper-based materials are by far the largest groups. Due to their chemistry, both material groups have only limited barrier properties. That means there are interactions possible. To prevent undesired interactions, like loss of aroma or leaching of undesired substances from the contact materials, there are plenty of regulations.
KS: What are MOSH/MOAH*? Where are they commonly found and how do these contaminants get into our food? (*MOSH: Mineral oil saturated hydrocarbons; MOAH: Mineral oil aromatic hydrocarbons)
EL: MOSH and MOAH are abbreviations that represent the two groups of chemical structures that can be found in refined mineral oil fractions. MOSH stands for mineral oil saturated hydrocarbons and MOAH means mineral oil aromatic hydrocarbons. Both groups consist of an enormous number of hydrocarbons with different structures and molecular weight distribution. Presently, with the methods used, a range from C10 to C50 is determined.
It is really challenging to almost impossible to spot sources of MOSH/MOAH in food. The first findings dating back to 1990, were the use of batching oils added to jute bags to keep the fibers flexible. These jute bags were used for different food materials like nuts, coffee, cocoa beans or grains. Then recycled cardboard was identified as one of the major sources for contamination, mainly due to mineral oil-based printing inks which were not fully removed during the recycling process.
In recent years, the packaging industry has invested a lot to improve the technology by e.g. using functional barriers. We have seen a decrease in the mineral oil concentration in food, but it is not fully eliminated due to other diffuse sources. This can range from emissions from combustion processes, to leaks during food production, to the mineral oil-based pesticide formulations used, to name a few.
KS: Can you explain how you quantify MOSH/MOAH in food? What features make the system you are using so suitable?
EL: There is a method available based on an online combination of normal phase liquid chromatography (LC) directly coupled to gas chromatography (GC) with two identical columns and flame ionization detection (FID). On the LC, two fractions (MOSH and MOAH) are separated and directly transferred on two column combinations (retention gap and analytical column) in one GC oven. First, up to 450 µl of the MOSH is transferred to the first GC column, then the second 450 µl portion (MOAH) is transferred to the second column. For the removal of the large amount of the solvent, a split valve is positioned between the retention gap and the analytical column. After the largest amount of the solvent is removed, the split valve is closed, the temperature program is started and MOSH and MOAH are analyzed simultaneously. In fact, due to the applied temperature ramp and the complexity of the composition, only “humps” are eluted. These humps were integrated without further identification due to the used FID. Nevertheless, the advantage of FID is the identical response of the quantified hydrocarbons even with large structural differences. For the verification of the analytical process, nine different internal standards are used to verify a correct analysis.
KS: Are there global regulations in place currently to limit MOSH/MOAH contaminants in food contact materials? Do you think your method could form part of routine regulatory monitoring and how do you foresee this could be implemented?
EL: At this time, especially in Europe, discussion about legal limits are ongoing. So far there are no legal limits, but at the moment products with MOSH below 2 mg/kg and MOAH below 0.5 mg/kg is acceptable on the market. For the vast majority of samples, the method can be used for routine monitoring. Nevertheless, there are samples where you cannot get a clear result. This is also addressed in a guideline of the European Joint Research Center published 2019 asking for additional confirmatory analysis in suspicious cases.
KS: What other further research are you conducting around MOSH/MOAH analysis? Are there alternative methods and techniques you are looking at?
EL: One of the open questions is still the toxicology and the toxicological evaluation of MOSH and MOAH. Both groups show different behaviors in terms of accumulation in the human body and toxicity. Due to the complexity we need additional information on the composition. At present, we are working on a project where we are combing Ames tests with advanced methods like two-dimensional comprehensive GC x GC on subfractions to get more detailed information.
KS: Apart from MOSH/MOAH, what do you think will be the next big threat in the field of food contact materials? How are you intending to address them?
EL: Now, I see tremendous changes in the food contact material segment. All the global discussions about environmental issues will have a dramatic impact on food contact materials. But by exchanging one product group for another, I will definitely expect an impact on the quality of the packed food in terms of stability and shelf life. So here we need again selective, sensitive and robust methods to be prepared for the change.
Professor Erich Leitner was speaking to Dr Karen Steward, Science Writer for Technology Networks.