OTR vs WVTR: Which Barrier Properties Matter for Ready Meal Packaging?
OTR and WVTR measure two different things, and a ready meal pack usually fails for one of them rather than both. OTR describes how oxygen moves through a packaging structure, where the food is sensitive to oxidation. WVTR describes how moisture vapour moves through it, where the food is sensitive to drying out or to taking on moisture.
Which one matters more is decided by the food, not by the packaging. This guide explains what each measurement covers, how to match the two to a product, and how to request barrier data for the exact finished structure rather than for a film sample. For the structures themselves, see our guide to EVOH-laminated bagasse trays for MAP and VSP lines.
What OTR covers
Oxygen transmission rate describes how much oxygen passes through a packaging structure under defined conditions. It is the measurement that matters when oxygen contact changes the food: fats turning rancid, colours fading, vitamins degrading, or a modified atmosphere inside the pack being lost.
For a sealed ready meal tray, the oxygen path is the complete structure - the fiber base with its functional film, and the lidding film sealing the top. A figure measured on a film alone does not describe the pack.
What WVTR covers
Water vapour transmission rate describes how much moisture vapour passes through the same structure under defined conditions. It matters when the food would dry out, lose texture, form ice crystals in frozen storage, or when a dry component would take on moisture from a wet one.
WVTR is also the measurement that explains why the fiber base cannot be evaluated without its functional film: an unlaminated fiber tray is not a moisture barrier, while a laminated tray is, and the difference is the film.
Which barrier matters for which food
| Food type | Barrier that usually matters most | What to request from the manufacturer |
|---|---|---|
| Fresh meat and seafood | Oxygen barrier, because colour and oxidation drive quality loss | Barrier data for the complete tray and lidding film structure under your storage conditions |
| Cooked prepared meals with sauce | Moisture barrier, because drying and sauce migration change the meal | Seal integrity and moisture barrier data for the finished pack |
| Frozen meals | Moisture barrier, because ice crystal formation follows moisture movement | Barrier and seal data across the frozen storage range |
| Meals combining wet and dry components | Both, because one component can dry out while the other takes on moisture | Barrier data together with the compartment layout and lidding film used |
| Ovenable and microwave meals | Seal and film performance at temperature, ahead of barrier | The film structure, its temperature capability and the reheating test results |
Those two measurements are not interchangeable, and neither of them replaces seal strength. A structure can hold a good barrier figure and still fail because the seal leaked, which is why seal integrity testing comes first in any packaging project.
Why the tray and the lidding film must be measured together
The barrier of a sealed pack is the barrier of the whole system: tray, functional film, lidding film, seal, and the gas mixture if the pack is a MAP pack. The lidding film can be the limiting layer or the tray can be, and which one it is only becomes clear when they are evaluated as a pair.
This is also why the lidding film and the functional film are matched in the same project, and why our MAP packaging solutions are specified as a tray-and-film combination rather than as a tray with a film added later.
Why we do not quote barrier numbers as a specification
Barrier results depend on the structure tested, the test conditions used, the thickness of the functional film and the food involved. A single number presented as a tray specification would therefore be misleading, and we do not publish one. What we do is provide the data that applies to the structure you are actually ordering, together with the test method and the conditions, so your technical team can judge it against your own requirement.
Test documentation for the laminated tray series is available through our test reports section, which covers REACH, POPs, PFAS, PPWR total fluorine and BPA alongside the certification set of FDA, LFGB, OK Compost Industrial and ABAP. Our laminated trays are PFAS-FREE (ND, < 10 ppm) and ≤ 5% plastic, and our film-free range is 100% plastic-free.
How to request barrier data from a manufacturer
A useful request describes the pack and the conditions, not just the film. Include:
The tray format, depth and compartment layout
The functional film and lidding film you intend to run
The food, including fat and moisture content
The storage temperature and the storage period you need to protect
Whether the pack is standard sealed, MAP or VSP
The barrier figure you are judging against, and the test conditions behind it
Where the tray is developed from an existing plastic tray, our 1:1 plastic tray replacement process keeps the format the same while the barrier question is answered on the new structure. Our mold library holds more than 3,000 in-house molds, and we develop 200+ new molds each year.
Frequently asked questions
Do we need OTR and WVTR data for every project?
No. Which of the two you need, and how much detail, follows from the food and the storage period. For a food that is sensitive to both oxidation and moisture movement, both sets of data become relevant.
Can you supply a barrier specification for the tray alone?
We describe barrier performance by structure rather than by tray, because the functional film and the lidding film both take part in the result. The relevant data is therefore provided for the combination you order.
Does a higher barrier always mean a better pack?
No. Barrier is one requirement among several. A higher-barrier film can change sealing behaviour, film handling and the reheating performance of the pack, so the structure is selected against the whole requirement, not against barrier alone.
What matters more, barrier or seal integrity?
Seal integrity comes first, because a leaking seal defeats any barrier the structure might otherwise provide. Barrier work starts once the seal has been established on the actual tray and lidding film combination.
Are fiber trays suitable for both MAP and VSP formats?
Laminated fiber trays can be developed for both formats, with the structure matched to the process. The wider specification is covered in our guide to ready meal packaging.
Need barrier data for a specific tray and film?
Hebei Mountain Environmental Protection Technology Co., Ltd. manufactures laminated bagasse trays and supplies film structures in PP, PET, CPET, PLA, EVOH-enhanced and PBAT-based options, with 30+ production lines for volume supply. Our range includes bagasse heat seal food trays and high barrier fiber trays for chilled, frozen and ready meal formats.
Tell us the food, the storage conditions and the structure you are considering, and we will confirm which barrier data applies and how it was measured. Please contact our team to start the request.
