The industry - mainly in Germany - has come under pressure to tackle mineral oils after lab analysis in 2009 by the Zürich Canton Laboratory first found potentially dangerous mineral oils could migrate into food.
This July, consumer group Foodwatch – founded by former Greenpeace director Thilo Bode – detected mineral oils in the packaging of some Lindt and Ferrero products in Germany.
It urged the companies to recall the products and set strict limits on the contaminants.
The EU currently has no legal limits on mineral oils in food, but Germany is currently drafting a national “mineral oil regulation”.
Ferrero said in a statement its products were safe and added “mineral oil exists nearly everywhere in the environment”. Lindt said it had initiated an action plan to combat mineral oil residues.
No legal limits
Mineral oils are derived from crude oil and coal and are indigestible, while some types are carcinogenic.
There are two types of mineral oil hydrocarbons: MOSH (Mineral Oil Saturated Hydrocarbon) and MOAH (Mineral Oil Aromatic Hydrocarbon).
According to a 2012 European Food Safety Authority (EFSA) opinion, MOAH could be mutagenic and carcinogenic.
Mineral oils in other industries
Mineral oil contamination is not limited to the chocolate industry. According to SGS, mineral oil hydrocarbons from packaging to dry and durable foodstuffs has the potential to contaminate foods such as breakfast cereals, pasta, rice, semolina and baking mixtures. SGS says there is currently insufficient data to make comparisons between food categories.
Jute bags for cocoa
Speaking to ConfectioneryNews, Dr. Silke Elwers, scientific consultant at ForestFinest Consulting said: “Sometimes they get into the product during processing.”
For example, chocolate advent calendars made with recycled cardboard were called out for mineral oil contamination by German consumer group Stiftung Warentest in 2012.
The recycled cardboard used in the calendars was believed to contain mineral oils traces from printing inks used in the newspaper and magazine industries.
But Elwers said: “I think the more important contributing factor for MOSH/MOAH could be storage and transport [of cocoa beans] in jute and sisal bags.”
The consultant said these bags were often made from plants extracted using mineral oils, which can transfer to the beans.
Cocoa supply chain
Mineral oil-free certified jute bags exist, but are not used in all origins, according to Elwers.
She added that cocoa beans are also often dried on asphalt, which can contain mineral oil residues.
Another potential contention source is from cardboard, which is used to line containers transporting cocoa, she said.
ForestFinest works with companies to identify the source of cocoa contaminants within the supply chain before taking remedial action.
Lab analysis
Constance Voigt, lab manager at SGS Germany, cited paperboard and corrugated cardboard as possible sources of mineral oil contamination in chocolate, but also pointed to lubricants or release agents during manufacture, production or transport as another cause.
“Instead of using recycled cartons, food companies may move towards alternatives, or adding layers that act as a barrier for items packed in paper and/or paperboard,” she said.
“However, the safest way to guard against MOSH/MOAH contamination is regular lab analysis.
“Only if companies do a risk assessment of their own products are they able to avoid migration of MOSH/MOAH along their supply chain,” she continued.
SGS Institut Fresenius in Berlin has established a qualitative and quantitative analysis method for MOSH/MOAH in all foodstuffs and packaging materials.
Dr. Reinhard Matissek has been leading research into the area on behalf of German confectionery association BDSI, and has developed a toolbox to detect contamination sources.
The toolbox is available online only to BDSI members.