Baby food sealed for safety
Babies and infants require particular protection from contaminants in food, as they are more sensitive than other consumers. Dr Ulrich Nehring, food technologist and former head of Nehring Institute (now owned by Eurofins), explains how the use of polyvinyl chloride (PVC) seals in jar closures poses a safety risk to baby food in glass packaging, and discusses safer alternatives.
When testing food for babies and infants, Nehring said biological contaminants such as Listeria or Salmonella, chemical contaminants such as mycotoxins from mould, and physical contaminants such as printing ink from packaging, as well as the content of essential nutrients, are of particular significance for food safety.
Besides pesticides, heavy metals and mycotoxins, there have also been concerns about PVC plasticisers entering infant food since the 1990s. Sources for plasticisers in baby food can be any item made of plasticised PVC which comes into contact with food or its ingredients, including plant components such as tubes or conveyor belts and the seals in jar closures for baby food in glass packaging.
“Plasticisers are evenly distributed in the PVC of the sealing compounds for jar closures but they are not chemically bonded with the plastic. The PVC seals in jar closures comprise 30 to 50% plasticisers,“ Nehring explained. “If food components migrate into the sealing compound — which inevitably happens when food comes into contact with the seal — the plasticisers can dissolve in part from the sealing compound and migrate into food.“
He said plasticiser migration happens more in fatty foods, occurs faster at higher temperatures and does not diminish during the storage of packaged food, so the longer food has been stored in glass packaging, the greater the concentration of plasticisers in the food.
In 2007, the EU Commission issued an amendment of Directive 2002/72/EC on the use of various plasticisers in materials and items made of plastic coming into contact with food. This legislation overrides the Federal Institute for Risk Assessment (BfR) statement 010/2005 which recommended industry to dispense with the use of phthalates in sealing compounds for lids, particularly for fatty foods.
“Accordingly, a range of phthalic acid esters (phthalates) may only be used as plasticisers in single-use materials and items with food contact if there is no contact with fatty foods. Contact with baby and infant food is not permissible,” Nehring said.
“These restrictions focus on fatty foods because plasticisers are fat-soluble and therefore migrate heavily into fatty foods, while barely any migration by plasticisers is established for low-fat or fat-free foods.
“Babies and infants have comparably low body weights and their diets are frequently based on less diverse food. It makes sense, therefore, to make a special regulation for this consumer group concerning the use of certain plasticisers.”
As well as banning the use of harmful plasticisers that come into contact with baby and infant food, Nehring said that “new plasticisers have been developed whose chemical properties make it more difficult for them to leach from the PVC and migrate into food”.
He noted that sealing compounds for glass closures which are not manufactured from PVC but from thermoplastic elastomers (TPE) offer a safer alternative — for example, PROVALIN.
The PVC-free sealing compound PROVALIN was tested at Nehring Institute for its food safety conformity. Tests included looking at global migration with various food simulants, the extent to which the sealing compound has an influence on the sensory characteristics of food, and to what extent many unanticipated substances can migrate from the sealing compound into food.
“As a result, we were able to fully confirm the food-safety conformity and health safety of PROVALIN,” Nehring said.
While it has been available for several years for metal vacuum closures, the PVC-free sealing compound has also become available for baby food in glass jars with press-on twist-off (PT) caps. This is important, Nehring said, as some baby food has a high fat content and the concentration of migrating substances is higher due to the small packaging sizes, meaning a high volume of contact between food and packaging material.
“For baby food in glass packaging, PT closures with PVC-free sealing compounds made from thermoplastic elastomers are a good and safe alternative to PT closures with conventional sealing compounds made from plasticised PVC,” Nehring concluded.
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