When we onboarded our products to High Pressure Processing (HPP) earlier this year, one of the most frequently asked questions from you guys was whether the pressure could increase plastic migration into the food.
To be honest, we were surprised to see this concern raised since the research that has been done on this front showed that migration in packaging is largely driven by temperature, not pressure. Because HPP is a non-thermal process, the European Food Safety Authority’s (EFSA) scientific evaluation found that packaging exposed to HPP stayed well below established safety limits. Even when plastic packaging was subjected to pressures, temperatures & hold times above the parameters that we use for our products, studies have shown that plastic migration did not significantly increase compared with packaging that didn’t go through HPP. [1]
However, in science, results can always vary under different parameters. What if things looked different with the specific packaging we were using or our HPP parameters changed how the plastic behaved under pressure?
So we decided to conduct our own testing and contributing to the growing body of data and research on HPP. We worked with scientists at Eurofins, an ISO-accredited lab to on the study design and their labs carried out the testing. Six months later, here's what we found.
HPP is a food safety technology that we use to eliminate harmful bacteria like Salmonella and Listeria by using water pressure instead of heat, keeping our product raw and nutrients intact. It’s the same technology behind the cold-pressed juices, guacamole, and deli meats in your fridges! If you want to learn more about HPP, we did a deep dive into the science behind HPP and how it impacts nutrients, beneficial bacteria, and fat oxidation in our food.
Plastic migration occurs when small amounts of material transfer from packaging into the food it’s in contact with. It happens because food naturally pulls trace amounts of material out of whatever it’s touching – think of it like how a sponge absorbs liquid. Plastic usage in our daily life has doubled since the 2000s, leading to more microplastic exposure which can accumulate our bodies. While more research is being conducted on exactly what levels cause harm in us and our pets, most people are looking to avoid scenarios that increase exposure.
Heat is known to be the biggest driver of plastic migration; just think back to how you were told “don't microwave things in plastic containers.” With HPP, although cold water is used throughout the process, the question is if the high pressure can also accelerate migration.
With that being said, some level of packaging migration occurs with any material (paper, plastic) and under the vast majority of circumstances, it does not impact our health. The EU’s regulatory limit on how much plastic migration can occur before it's considered a safety concern is 10 mg per square decimeter [2] – roughly a small pinch of salt scattered across a sheet of paper.
To test the amount of packaging that migrates into a substance, you first put the packaging in contact with a substance under the scenario (ex: 40F for 10 days) you're evaluating. Afterwards, you evaporate the substance and whatever packaging material was absorbed gets left behind as a residue and can be measured & weighed.
These tests are commonly conducted using a food simulant such as water, acetic acid, vegetable oil, or ethanol to represent the "worst case" scenario. You don't want to use an actual food substance since you won't be able to distinguish if the residue post evaporation is from the food itself or the packaging. We chose ethanol as our simulant because it’s a polar solvent, which means it does a better job ‘melting’ plastic and increasing migration
Ultimately, what we were looking for was a comparison of migration amounts between HPP and non-HPP packages.
We ran three packages that underwent HPP and three controls that did not, each filled with ethanol. The charts below show the residue per surface area across the samples. A higher residue per surface area indicate that more migration occurred.
From the charts above, you can see there was no statistically significant difference in Residue per Surface Area between samples that did and did not undergo HPP which confirms that HPP did not increase plastic migration. Both groups also came in 10x lower than the EU’s 10 mg per square decimeter threshold. Since this testing was done with ethanol to model a worst-case scenario, the migration that occurs with our food matrix would be even lower than these levels.
To understand why there was no increase in plastic migration, it helps to think about how HPP works. High pressure disrupts a class of weak bonds called hydrogen bonds that are found within bacterial cells. When these bonds break down, the cell dies and that’s exactly what makes HPP effective at eliminating pathogens.
Plastic packaging, on the other hand, is held together by covalent bonds – a significantly stronger class of bonds that are unaffected by pressure levels used during HPP. Covalent bonds are also what hold nutrients like amino acids, vitamins, and fatty acids together, which is also why our nutrient testing also showed no meaningful change before and after HPP.
[1] EFSA Panel on Biological Hazards (BIOHAZ Panel), "The efficacy and safety of high-pressure processing of food," EFSA Journal 2022;20(3):7128. https://doi.org/10.2903/j.efsa.2022.7128
[2] Commission Regulation (EU) No 10/2011 of 14 January 2011 on plastic materials and articles intended to come into contact with food, Article 12(1). Consolidated version: ttps://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:02011R0010-20230831
