Drs. Ing. Hassan El khallabi || Head of Laboratory || Normec Green Agro Control
What do we mean by MOSH and MOAH?
MOSH and MOAH are two broad fractions of mineral oil. MOSH stands for Mineral Oil Saturated Hydrocarbons and includes saturated aliphatic and cyclic hydrocarbons. MOAH stands for Mineral Oil Aromatic Hydrocarbons and consists of aromatic hydrocarbons with one or more aromatic rings.
Each is a complex mixture of hundreds to thousands of components derived from petroleum. These substances have no technological function in food, but may enter it unintentionally. This can happen, for example, through packaging materials such as recycled cardboard and printing inks, but also through lubricants, process aids, coatings or environmental contamination.
What analytical techniques does a laboratory use to determine MOSH and MOAH?
For reliable results, we combine several analytical techniques. The basis is an LC-GC-FID platform, performed in accordance with EN 16995:2017: the recommended standard for MOSH/MOAH analyses.
This standard ensures reproducible results and is widely accepted by bodies such as EFSA. This makes the method suitable for audit purposes, certification and compliance with laws and regulations.
The analysis proceeds in three steps:
- First is sample extraction. The purpose of this step is to release MOSH and MOAH from the food and separate them from water, proteins and other matrix components. Usually we use solvent extraction with, for example, hexane or a mixture of hexane and dichloromethane. For more difficult matrices, techniques such as Soxhlet extraction or accelerated solvent extraction (ASE) can be used.
- This is followed by separation and purification. In this step, we separate MOSH and MOAH from each other and from natural fats. This is often done by column chromatography on silica or alumina. In some methods, HPLC is also used as a preliminary separation step, especially to further purify the MOAH fraction.
- Finally come detection and quantification. The most commonly used technique for this is gas chromatography with flame ionization detector (LC-GC-FID). With this, we determine the MOSH and MOAH fractions based on their carbon chain profiles.
For very complex matrices, two-dimensional gas chromatography (GC×GC-FID) can be used to achieve a higher degree of separation. Mass spectrometry (GC-MS or GC×GC-MS) is sometimes used for structural confirmation, but less frequently for routine quantification.
How are the results interpreted?
Results are reported as MOSH and MOAH fractions within specific carbon ranges, e.g., C15-C35. In addition, the total sum of the fractions is also given, consistent with the analytical nature of these complex mixtures.
Concentrations are expressed in mg/kg product. In interpretation, we look at both the individual fractions and the total sum concentration and compare them with applicable legislation, guideline values or risk assessments. On this basis, we estimate whether the presence of MOSH and MOAH is acceptable from a food safety perspective, taking into account any measurement uncertainty.
Why are MOSH and MOAH usually determined as carbon groups and not as individual substances?
This is mainly due to the nature of these contaminants. This is because MOSH and MOAH are not individual, well-defined substances, but very complex mixtures of hundreds to thousands of different hydrocarbons.
Identifying and quantifying all of these components individually is analytically impractical. Therefore, they are grouped according to their chemical structure - saturated or aromatic - and their carbon number range, e.g., C15-C35. By measuring these fractions, we obtain a reliable and reproducible indication of the total MOSH and MOAH load without having to analyze each individual compound separately.
Why is the determination of MOSH and MOAH in some matrices so difficult?
Analysis becomes especially challenging in complex or high-fat matrices, such as chocolate, spices or vegetable oils. Natural lipids, such as triglycerides and sterols, can interfere because they exhibit similar carbon chain lengths and chromatographic behavior as MOSH. As a result, signals may overlap.
In addition, mineral oils can bind to food components such as proteins or fibers, making extraction difficult. The often low concentrations of MOSH and MOAH relative to total fat content make detection even more difficult.
On top of this, the high chemical diversity of these mixtures makes analysis complex. Advanced chromatographic techniques are therefore necessary to ensure reliable separation and quantification.
In which raw materials and materials does it make sense to analyze MOSH and MOAH?
MOSH and MOAH analyses are particularly relevant in raw materials and materials where there is a real risk of mineral oil contamination.
This applies primarily to fatty products, such as vegetable oils and fats, cocoa, chocolate, nuts and seeds. These products can absorb mineral oils relatively easily. Dry products such as grains, flour, rice, herbs and spices are also sensitive, e.g. through contact with packaging materials during storage and transport.
In addition, analysis is important with food contact materials, such as recycled paper and cardboard, printing inks, adhesives and coatings, because of possible migration. Finally, process aids, such as lubricants and release agents, also deserve attention when there is a risk of contact with the product.
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