BPA is used in the production of a thermosetting epoxy lacquer, offering thermal and chemical stability, which allows food tins to last for several years and ensure the microbiological safety of the food they contain. This lacquer may also serve to preserve the organoleptic properties of the food.
At present, there is no universally reliable and applicable solution for replacing epoxy resins in food tins and drinks cans.
There are two possible approaches:
- either to use another type of packaging compatible with appertisation, such as a carton (e.g. Combifit® or Tetra Recart®), or a soft bag (Doypack®);
or to remove the BPA from the epoxy resin protecting the inside of the food tin. The SNFBM (French union of metallic packaging producers) indicates that four types of resins are currently used as alternatives to BPA-based epoxy resins in food tins and lids for glass jars.
- Acrylic lacquers
- Organosol lacquers
- Polyester lacquers (aminoplast, phenolic, urethane)
- Vinyls
These solutions are used, in particular, for food containers aimed at children under 3, in which BPA has been banned in France since 1 January 2013. The foods in question are not very corrosive, being neither too acidic nor too salty.
For other tinned products, it would appear that these 4 solutions could be suitable in most cases, but tests have to be carried out for each product, as we can never be certain how the lacquer will behave. Furthermore, we do not have a safe solution at present for certain more corrosive food products.
Other solutions are under development, but none has received final approval as yet. These solutions include new resins that could replace BPA-based epoxy resins, as well as epoxy resins that use a monomer other than BPA. A few examples are given below to illustrate the situations for which replacements are required:
- In the USA, Eden Foods has marketed tinned foods with oleoresin-based coatings. These resins do not withstand the acidity of some foodstuffs, such as tomatoes.
- The French National Institute for Agricultural Research (INRA) and the chemical engineering school ENSCM Montpellier are conducting promising research on polyphenol-based resins deriving from bio-sourced tannins, and industrial tests are planned for the months ahead.
Information about the progress and completion of this research work will be provided regularly on the SNA-BPA site.