Michaela Dvorakova
(MFood Tech, R&D Specialist)
Food packaging is an important aspect of food processing and functions as an intermediary between food production and consumers.
Food packaging is used to ensure:
- safe preparation
- transport
- distribution
- storage
- retailing
- delivery of food to consumers
while maintaining maximum quality, which is done by preventing the deterioration of foods by microbes, resulting from exposure to air, moisture, or pH changes associated with the food or its surrounding atmosphere.
In this article, we will focus on the types of food packaging materials, the chemical interactions between packaging and food products, and whether packaging materials pose potential health hazards.
Types of food packaging materials
There are several materials which are used for food packaging. It depends on technical requirements throughout the supply chain or marketing needs. The layer that is in direct contact with food is called “food contact material”.[1]
Plastics
Common types: Polyethylene (PE), Polypropylene (PP) and Polyethylene Terephthalate (PET).
Applications: Usage in various types of food packaging, such as bottles, wraps and containers.
Metals
Types: Aluminium and tinplate.
Applications: Cans, foils and lids.
Paper and cardboard
Types: Waxed paper, laminated paper and corrugated cardboard.
Applications: Boxes, cartons and wrapping.
Glass
Applications: Bottles and jars.
Biodegradable and compostable materials
Types: Polylactic acid (PLA), starch-based plastics and edible films.
Applications: Eco-friendly alternatives for traditional packaging.
As we can see in the chart above, plastic is the most used material for packaging.
Chemical interactions between food and packaging and potential health hazards
It is recognised that chemicals from packaging can migrate into the food and be ingested by consumers, but any of those particles should not be in quantities which can cause harm to the human body.
Chemical migration is the transfer of some chemical compounds from packaging to the food under certain conditions. We can recognise two types of migration:
- overall migration (migration of all substances from the packaging)
- specific migration (migration of particular substance)
Monitoring of these migrations is a crucial part of ensuring food safety.
Glass and metal can be classified as inert materials, which means they do not allow the migration process. Other materials like plastics, printing inks or coatings are defined as permeable materials.
List of factors which can have an impact on migration:
- Physicochemical properties of material and food
- Environmental conditions
- Foodstuff volume
- Packaging size
- Packaging substrate type and content (carton, plastics, silicone, etc.)
- Permeation of the packaging material
- Characteristic of the food (fatty, acidic or dry)
- Chemical structure of migrants (polarity, molecule size, etc.)
- Direct or indirect contact of material with food
- Contact surface area
- Contact time, temperature and humidity (migration value increases with contact time and temperature)[2,3]
There are possible health risks associated with long-term exposure to chemicals appearing in packaging materials.
Paper and cardboard
Paper and paperboard (or cardboard) have been key material for the entire packaging industry. The categories are divided by its thickness and weight on light paper and thicker cardboard.
The main source of paper is wood. In the first step we have a wood pulp, from which cellulose fibers are extracted and removed, including other components such as hemicellulose and lignin.
Usually different chemicals like sodium hydroxide, sodium sulphite or sulfurous acid are used. Once the pulp is clean, it goes through a series of refining, forming, pressing, drying and optional bleaching until we have the paper we want.
Advantages of using paper and cardboard as food packaging material
The biggest advantages of paper as food packaging are:
- low cost
- easy collection
- lightweight
- biodegradable
- flexibility
- reuse
- recycling
It’s possible to combine it with different materials like oil, wax or plastics to improve its gas or wet barrier properties.
Main properties of paper and cardboard rely on purity, type and shape of raw material (wood pulp), moisture content and amount of other chemicals. These are:
- Weight
- Thickness
- Gloss
- Density
- Whiteness
- Brightness
- Strength
- Stiffness
Disadvantages of using paper and cardboard as food packaging material
Paper and cardboard as food packaging also has some disadvantages. Compared to other materials it’s mainly limited durability and strength, vulnerability to moisture, space and storage requirements and limited barrier properties.[4]
Usage of paper and cardboard
Wax and kraft paper are used mainly as wrapping paper or for grocery bags. Then we use paperboard, which is usually combined with other materials (mostly plastics) to create multilayer food packaging for liquid and dry foods, frozen foods and fast foods.
Chemical reactions and potential health hazards
Substances which can migrate from the paper and cardboard are mostly chemical additives, categorised as processing aids (assisting during the preparation process) and functional additives (enhancing the properties of material).
Major migrants are:
- mineral oils
- dyes (organic, anorganic or synthetic)
- phthalates
- adipates
- polyfluorinated substances
Another concern with paper food packaging is because of the ink. According to International Regulations and Guidelines on Printing Inks, the printed surfaces shall not come into direct contact with food.
However, in developing countries like Nigeria, they use materials such as newspapers to wrap food. Food packed in such a manner can have amounts of heavy metals like titanium chromate, molybdenum or iron. Heat and presence of water or oil can only increase the amount of these metals.
The German group studied infant foods packed in recycled paperboard boxes with coated paper liners. Food was contaminated with diisobutyl phthalate and di-n-butyl phthalate, which are considered as endocrine disruptors and have typically male reproductive toxicity.
Infant foods might contain endocrine disruptors if packed in recycled paperboard boxes
Also, in 2010 Kellogg Company recalled 28 million boxes of cereal because of elevated levels of methylnaphthalene, which is classified as possible human carcinogen.
Other studies have been conducted to measure migration of mineral hydrocarbon wax from waxed papers. Migration to the wax was increased due to higher temperature. Bread samples outer layer contained up to 50mg/kg, toffee products contained 110–1300mg/kg and wrapped sweets contained 12–1300mg/kg level of mineral hydrocarbon on the product surface.
For imparting oil and water resistance to paper we use polyfluorinated surfactants (PFS). It is common for paper bags or boxes used for microwavable popcorn, burger boxes, rye bread mix, coffee or noodles. However, oxidation products of PFS are toxic and can cause endocrine disruption.
Another substance, which can migrate from paper and cause endocrine disruption, is Bisphenol S. This substance is used as a colour developer on thermal receipt paper and had been proposed to be banned from its usage from 2020.[5,6,7]
Environmental concerns
The pulp and paper industry is the third largest consumer of water and fifth largest consumer of energy worldwide and it also consequently generates high amounts of waste and pollution.
Recycling of the paper though reduces the carbon footprint and recycling a single newspaper can save 41 000 trees from being cut down, since paper can be recycled 6-7 times before fiber lengths are reduced.
Glass
Glass is usually used for many food products, ranging from heat treated and pressure-packed solids and powdered products to liquids.
Glass does not have free and mobile electrons that absorb light energy, therefore, glass is transparent and translucent. However, coloured glass can be made and used for example for protection of oils or wines from deteriorating effects of light.
Glass is made from silica (sand), sodium carbonate, calcium carbonate and alumina.
Mixtures of these substances are treated by high temperatures. Liquid mix is then poured into the molds and cooled. To make a coloured glass, colourants are added to the mix.
The most common colourants are chromium oxide (green), iron sulfur and carbon (brown) and cobalt oxide (blue).
Advantages of using glass as food packaging material
Glass is a good material for food packaging. It is tough, durable and chemically inert material, therefore it has no interaction with food and it’s safe for use. Also it doesn’t react with chemicals and it doesn’t corrode, even without special coating.
Glass does not change form, it is resistant and suitable for sterilisation and cleaning processes. It has a shiny and smooth texture and it’s reusable and recyclable.
It is suitable for vacuuming, filling and closing methods, which is helpful for food easy to spoil. Also it can’t be degradable by microorganisms.
It has no permeability for gas, liquids, water vapor and odor.
Disadvantages of using glass as food packaging material
Glass allows light to pass through which can be problematic for products sensitive to light. Another disadvantage is its fragility, which can be complicated for transport and storage. Also its weight can cause higher prices for shipping.
In comparison with plastic materials manufacturing of glass generates three times more air pollution, manufacturing itself is more pricey and also more energy consumption is required than with other materials.
Chemical reactions and potential health hazards
Glass is an inert material, therefore it’s generally recognised as safe. However, some glass bottles and jars may contain lead.
Researchers from the Institute of Environmental Geochemistry of the University of Heidelberg in Germany assessed 125 brands of drinking water from 28 countries. Their results showed that water packaged in glass bottles contained 26–57 times more lead than comparable waters bottled in polyethylene terephthalate (PET) plastic. The increased lead content appeared to be a result of leaching from glass containers.
Another study showed that there might be an issue not from glass itself, but from materials used to seal the metal lids on glass jars.
Metal lids of glass jars might leech lead into water
The Danish group studied some foods in glass jars sealed with polyvinyl chloride (PVC) gaskets and they found phthalates in levels unacceptable for the European Food Safety Authority.[9]
Environmental concerns
Glass has a really big advantage in its recyclability, reusability and sustainability, since the raw materials are all products of nature.
That makes glass one of the most sustainable materials for food packaging.
However, there is 17-18 times more material (kg) needed for the production of a glass bottle, therefore its environmental impacts per bottle far exceed those of a plastic bottle.
Related Questions
1. What is metallised food paper packaging and is it safe?
Metallised paper is a paper product, which is coated with a thin layer of metal, typically aluminium.
This layer provides a range of functional properties, like barrier properties, heat resistance and printability. It is considered safe when food-grade coating is applied. This coating prevents migration of harmful substances.
2. Does greaseproof paper contain any chemicals that might possess risk to health?
Greaseproof paper has been a topic of concern because of the presence of per- and poly-fluoroalkyl substances (PFAS).
These substances are a manmade group of chemicals, which have the ability to prevent grease and water. If people and animals are exposed to it, it can increase the body leading to multiple pathological conditions.
Luckily, some brands are becoming more aware of PFAS and began to produce PFAS-free products.
Michaela is a qualified food technologist, originally from the Czech Republic, where she successfully graduated and earned a Master’s degree from University of Chemistry and Technology. Michaela’s field of study was chemistry and analysis of food and natural products, and upon finishing her studies she became a part of an R&D team focusing on nutritional plant-based food…
If you would like to learn more about Mihaela, see Expert: Michaela Dvorakova.
References
(1) Jane Muncke, Food Packaging Materials. Retrieved from https://www.foodpackagingforum.org/resources/background-articles/food-packaging-materials
(2) S. Yenidoğan, C. Aydemir, and C. E. Doğan, Packaging-food interaction and chemical migration, Cellulose Chemistry and Technology, vol. 57, no. 9–10, 2023, doi: 10.35812/CelluloseChemTechnol.2023.57.91.
(3) Abdullahi, N. (2014). Hazard chemicals in some food packaging materials (a review). Annals. Food Science and Technology, 15(1).
(4) Paper Papers. 5 Crucial Advantages and Disadvantages of Paper Packaging. Retrieved from https://www.paperpapers.com/news/disadvantages-of-paper-packaging
(5) I. S. Arvanitoyannis and K. V. Kotsanopoulos, Migration Phenomenon in Food Packaging. Food-Package Interactions, Mechanisms, Types of Migrants, Testing and Relative Legislation-A Review’, 2014. doi: 10.1007/s11947-013-1106-8.
(6) Jadhav, E. B., Sankhla, M. S., Bhat, R. A., & Bhagat, D. S. (2021). Microplastics from food packaging: An overview of human consumption, health threats, and alternative solutions. In Environmental Nanotechnology, Monitoring and Management (Vol. 16). https://doi.org/10.1016/j.enmm.2021.100608
(7) Kadac-Czapska, K., Knez, E., Gierszewska, M., Olewnik-Kruszkowska, E., & Grembecka, M. (2023). Microplastics Derived from Food Packaging Waste—Their Origin and Health Risks. In Materials (Vol. 16, Issue 2). https://doi.org/10.3390/ma16020674
(8) Deshwal, G. K., Panjagari, N. R., & Alam, T. (2019). An overview of paper and paper based food packaging materials: health safety and environmental concerns. In Journal of Food Science and Technology (Vol. 56, Issue 10).
(9) Claudio, L. (2012). Our food: Packaging & public health. In Environmental Health Perspectives (Vol. 120, Issue 6). https://doi.org/10.1289/ehp.120-a232
