Printing inks – Safety aspects for food packaging applications
Packaging is the calling card of a product. It gives the first visual and tangible impression of the product to the prospective buyers.
In addition to the information describing the package contents, the packaging provides lots of other useful references and tips about the material inside. It tells the purchaser about the price, size, condition and texture of the product, where and when it was made and when it should be used by. Food packaging is an immensely important segment in the packaging sector because it addresses both people’s basic needs and quality-of-life issues. It provides the consumer with a range of information that can be of crucial importance to their health: the degree of freshness, colour, shelf life, ingredients and nutritional values (such as the number of calories and fat content). But details such as the country of origin, the weight and production methods can also be important factors in consumers’ purchasing decisions. Depending on the design, the customer is given suggestions on how to prepare and serve the food, and in what quantities.
Packaging also takes on practical functions, such as protecting contents against damage and preventing them from going bad.
Many of the functions above can only be fulfilled by packaging if the packaging has printing ink applied to it. Ink is the often unnoticed information medium that both simplifies and makes our lives safer in many respects.
Many of the products packaged by the food industry are organoleptically-sensitive. Change in smell or taste spoils the people’s enjoyment of the products and must therefore be prevented at all cost. One of the main functions of packaging is to protect the food and prevent substances from transferring to the food or from the food. It is obvious that the packaging itself must under no circumstances have a negative influence on the quality of what goes inside it.
Principle of Food Packaging
No health risks to the consumers; No change in the taste, smell, colour or visual properties; No change to the composition of the contents; No contamination from the printed package; Maximum shelf-life; Zero risk to health.
Migration of Substances from Food Packaging Materials
First we need to clarify what kind of substances might be transferred into the food and how this transfer of unwanted substances works.
Any transfer of substances into food is important because it can have two negative impacts on food.
Food safety – Specific substances could be harmful to health if small amounts are ingested with the food on a regular basis.
Food quality – migrants might deteriorate the organoleptic properties or change the composition of the food.
Transfer of substances from the packaging to its contents can happen in three different ways: Through-migration; Invisible set-off; and Substance transfer via gas phase.
Substances of low molecular weight either from the ink and coating films or from the substrate can pass through the substrate to the packed food inside. This process is known as through-migration.
Folding Box Film Laminates
Ink Substrate Ink Adhesive Substrate
Because of the nature of printing process, the inks from the printed side will come in contact with the back side of the following printed sheet and may get absorbed easily in the form of invisible set-off. When these printed sheets are subsequently converted to folding boxes for food packaging this set-off side will face the packed food directly and can easily transfer the absorbed substances to the food stuff. Invisible set-off is also possible when printing is done in reel form.
In sheet form
In reel form
Migration of substances is also possible in gas phase even when the packed food is not in direct contact with the packaging material from inside.
Three types of barriers can be used for this purpose
• Permanent barriers: Glass and metals act as a reliable barrier to ink constituents. In the case of aluminium foil, it has to be thicker than 7 µm.
• Plastics films and layers are functionally-specific barriers: Plastics possess very different barrier properties in relation to different substances. For instance, while OPP films are a good barrier against water, they provide absolutely no barrier whatsoever to many constituent components of printing inks, such as mineral oils or some photo initiators in case of UVsystem.
• Non-functional barriers: Paper and board pose no form of barrier at all to the low molecular components of printing inks. These are mostly used as secondary packaging material along with some primary packaging having better barrier property.
Factors that Influence Migration
The substrate must satisfy the requirements of food packaging and be suitable for the respective printing process. Its own organoleptic properties must also not be ignored.
Design includes many factors: Selection of the right printing process, the amount of ink applied to the packaging plays an important role. The ratio of ink used vs weight of the packed content is important.
Transportation and storage, i. e. conditions related to logistics, can influence the occurrence and extent of migration. The prevailing conditions, such as temperature, moisture and ventilation, as well as any strong-smelling constituents that may be present, can also have negative effects on organoleptics and migration.
Only low-migration inks and coatings may be used when manufacturing food packaging without a functional barrier.
Especially when using UV-curing inks, the press speed will influence curing of the ink and may result in undesirable migration if curing is incomplete.
Adhesives must be suitable for food packaging.
Cleanliness of the press also plays a crucial role. Make sure that there are no residues of standard (non food-packaging) inks from the preceding production run or wash-up solution in the roller materials or somewhere else in the press.
Many parameters and conditions within the press can alter the results obtained when printing. The condition of UV or IR lamps and of curing units, and the level of maintenance of fount solution systems – in unfavourable circumstances, these factors can lead to critical migration risks. Proper maintenance is essential.
Legal Requirements of Food Packaging (European Regulations)
EC No. 1935/2004 Framework Regulation; EC No. 2023/2006 GMP Regulation; EU No. 10/2011 Plastic Regulation; Swiss Ordinance on food contact packaging materials; EuPIA Exclusion List; EuPIA Guideline; EuPIA GMP
Regulation (EC) No. 1935/2004 Framework Regulation
Regulation (EC) No. 1935/2004 sets the framework of European rules and regulations on materials and articles that, as finished products and under normal or foreseeable conditions of use, are intended to come into contact with foodstuffs.
Under these conditions of use, such materials and articles (and we are talking here primarily of packaging) must be manufactured so they do not transfer substances to the packed food that: do endanger human health; bring about an unacceptable change in the composition of the packaged food; or bring about a deterioration in the organoleptic properties of the packaged food.
Regulation (EC) No. 2023/2006 GMP Regulation
This Regulation lays down good manufacturing practices for materials covered by Regulation (EC) No. 1935/2004. It covers the same field of application as the Framework Regulation and is therefore applicable to all materials and not just plastics.
Regulation (EU) No. 10/2011 Plastics Regulation
This is a specific measure regulating the use of plastic materials and articles intended to come into contact with foodstuffs.
There are no specific measures applicable to printing inks and coatings/varnishes at EU level, neither to printing on the outside nor to printing on the inside of packaging, i.e. on the side that comes into direct contact with the food packaged.
EDI Ordinance on food contact materials (Swiss Ordinance) SR 817.023.21
Printing inks may contain only substances that are listed in Annexes 1 and 6.
The lists in Annex 6 are based on a compilation by the European Printing Ink Association (EuPIA) and were adapted by the Swiss Federal Office of Public Health.
The lists in Annex 6 "Printing Inks" are in two sections:
Section A: Substances that have undergone officially recognised scientific testing. Any migration limits (SML) specified in this list must be complied with.
Section B: Substances that have not undergone officially recognised scientific testing. Migration of such substances must not be detectable; detection limit = 0.01 mg/kg foodstuff (10 ppb).
Inks must be manufactured and applied in accordance with Good Manufacturing Practice.
EuPIA Exclusion List – Exclusion criteria for raw materials
- CMR substances (carcinogenic, mutagenic, reprotoxic substances)
- Toxic or very toxic materials
- Raw materials based on toxic heavy metals
- Further substances as specified in the list
EuPIA Guideline on Printing Inks – Requirements for the formulation of Inks
- Selection of raw materials in compliance with the selection scheme:
- Consideration of migration
- With regards to the EuPIA Exclusion list
- Ink production in accordance to EuPIA GMP
- No direct contact of printed surface & food
- No visible set-off
- Global migration and specific migration shall not exceed the relevant limits
- The inks must offer good adhesion to the substrates
- There must be no change in organoleptic properties
- All legal requirements must be complied with
EuPIA Guideline on Printing Inks – GMP requirements for the production of Inks
Traceability of all the raw materials used; Production must be controlled, monitored and documented; Conformity with the product specifications must be checked; Test equipment must be monitored; Correct packing in clean containers
The demands being made on food packaging by consumers, legislators and food manufacturers are very high. Hubergroup provides complete range of products suitable for food packaging that fulfil the regulatory requirements. With MGA, the Hubergroup is currently offering the highest level in safety on printing inks for food packaging. With the use of the "best available technology" substance transfer is kept on a minimum level and contamination risk is excluded. Similarly we offer Gecko range of products in solvent-based ink system, NewV MGA for UV inks and Acrylac MGA for water-based coatings for safe food packaging.
(The author is general manager, technical, Hubergroup India Pvt. Ltd. He can be contacted at firstname.lastname@example.org)