On average only 6% of a food product’s emissions is caused by the packaging, but for vegetables this is slightly different. Because they already have such a low footprint, the share of the packaging is often slightly bigger. Still, keep in mind that we’re now trying to answer a question about a part of your diet that already has a really low footprint. So before we get into the nitty gritty details, don’t overthink this!

It seems like an easy question but a lot of factors influence the final climate impact: how much of the glass is recycled, is this taken into account in the study? How long do you store the vegetables in your own freezer at home? Do you use renewable energy for this? How much of the vegetables do we waste, and does this depend on the packaging we choose? Do we waste more fresh than frozen, and how much?

As you can see from all these factors, there’s not one grand study that we can refer to that has a conclusive answer. Luckily there are a few case studies out there. They might be a bit older, because who wants to research frozen green beans each year? Nevertheless they are the best we got. So we will look at all the vegetable ingredients for one of our favorite recipes,  Spinach Pasta Pesto, to find out how these factors influence the best choice!

Green beans

We’ve already seen in this blog that green beans can have a very high footprint when you get them fresh outside of their season, mostly because they sometimes are transported by plane. So that already brings us to the first important conclusion: buying them in glas, frozen or canned is definitely a better idea than fresh when it’s not green bean season. If we compare these three options green beans in glass have the highest impact, then canned, and last (and the least!) frozen. By the way, it’s not the shown brands which were researched, those pictures are just for illustrative purposes. If you would recycle the glass, the emissions of the packaging itself will decrease 30-40%. The carbon footprint of the green beans in glass would then become similar to the frozen ones.

Spinach

Let’s now move to the spinach. This case study was done by the same researchers. They’ve looked at fresh, frozen and spinach in glass. As above, it’s not these exact brands that they looked at. I knew you could get frozen spinach, but apparently also in glass pots! Here you see a similar profile, glass has the highest climate impact, then frozen and fresh the lowest. Similar to green beans, you could reduce the glass impact by recycling the glass container. Although the impact of this for spinach is not explicitly mentioned in the report, it most likely puts spinach from a glass container almost at par with frozen spinach (just like it did for frozen green beans).

Canned tomatoes

Time for the canned tomatoes! We use them a lot at Fork Ranger, so I am very curious how they compare with fresh tomatoes. An older Austrian studycompared fresh tomatoes with imported canned tomatoes from Italy. As you can see the climate impact is roughly four times higher! And a big part of this is the packaging. But how can it be so high?

To dive deeper into this packaging part, we looked at a new Italian study. Who else would research this, but Italians? They also found that packaging contributes to two-thirds of the carbon footprint of canned tomatoes. But the story doesn’t end there. They’ve looked at two things: 1) what happens if we recycle the cans and 2) what happens if we choose glas jars instead of cans?

The first question is very relevant, as currently already a large part of the cans are recycled. Many European countries are already meeting the European 2030 recycling targets of 75% for glass and 80% for metal packaging. So including recycling in the calculations of the climate impact is justified.

The researchers found that when they would apply the current recycling rate in Italy, the carbon footprint of the packaging alone would decrease with 46%. And if they would achieve 100% recycling in a circular economy, the impact would be reduced by 57%. If you use these numbers and look at our first tomato study and the infographic, you see that cutting the packaging impact in half has quite a big impact on the total footprint.

Moving to glass was comparable to recycling the cans, and reduced the packaging’s footprint with 41%. And adding on top of that the recycling of the glass, the original footprint would be reduced by 80%!

Glass seems the clear winner, but what they didn’t include: because glass is heavier it will increase transport emissions. It’s hard to say how much exactly and whether this would shift the conclusions. And this is just one case, what if the transport distance is much shorter than in this case study or much longer? If we zoom out, we should keep in mind that it’s more important that we contribute to recycling of the cans or the glass, than making the right choice between these two. We’ve mostly used canned foods in our recipes (while there are also alternatives in glass), because of their cost: the canned option is often cheaper.

Comparing food waste with canned or frozen options

In all of the above case studies the impact of food waste in our own homes was not taken into account. And in an ideal world this would be perfect, if there would zero food waste. But is this also realistic?

My expectation is that we would waste less of frozen products, simply because we can use exactly the amount we need, and the rest wouldn’t go bad. How often have you had the case that a few leftover spinach leaves become a slimy mess? It happens to me even though I try to avoid it.

A Dutch study asked 500 households about their food wasting habits of fresh or frozen foods, most of them vegetables. They found that when households use the frozen product compared to the fresh one a lower amount is wasted. For green beans 20% less beans are wasted when frozen is compared to fresh. For spinach it’s even more, around 40%. So what happens to the climate impact of those frozen vegetables when we take into account the amount of food waste?

PRé Sustainability wrote a report for Nomads foods to see how fresh and frozen products compare in terms of carbon footprint, and they also included the impact of reduced waste of the frozen option. The results show that the CO2 impact of frozen spinach is 15% lower than fresh spinach. But it’s also fair to say the majority of this difference between fresh and frozen was due to other factors, and that a difference in consumer food waste was just a quarter of this difference.

Even though this study was funded by a frozen vegetables company, one of the independent reviewers said: “When buying something frozen, shoppers should feel comfortable not worrying about the embedded energy, because the odds are higher that they’re going to use and eat all of it.”

One last thing, but aren’t fresh veggies healthier?

Fresh fruits and vegetables sometimes give us the impression that they are healthier. But this is not the case! They provide the same nutritional benefits. Actually the micronutrients in fresh foods decrease the longer it takes from the field to being cooked in your kitchen. Frozen vegetables are shortly after harvest blanched and frozen, which retains the micronutrients.

Also the packaging itself has been under scrutiny. People have been avoiding tin cans because of BPA in linings in cans: a protective layer that between the can and what’s in the can. And this WAS for a good reason. The chemical BPA can migrate in very small amounts from the lining to the food and drinks itself. Research has shown that the amounts found in urine were higher than safety thresholds that were set, potentially impacting the immune system. But the good thing is: the EU recently adopted a ban of using BPA in food packaging. So don’t be hesitant to buy canned food (anymore)!

How we use canned or frozen vegetables in our own recipes

In our seasonal calendar we have plenty of recipes where we added canned or frozen vegetables. Outside of their season canned and frozen vegetables are a great addition to still eat a variety of vegetables and sufficient vegetables. But feel free to use the fresh counterparts when they are available.

For example, when you make the Spinach Pasta Pesto when green beans and spinach are in season, you want to use fresh ones instead of frozen ones! And you can even use fresh tomatoes instead of the canned ones mentioned in the recipe. In the winter time you can still make this recipe with frozen green beans, frozen spinach and canned tomatoes. Because we don’t have a way to make our recipes super-flexible and we want recipes that are longer in season, for other recipes we’ve sometimes settled on choosing canned or frozen ingredients in the standard recipe.

Conclusion

The first conclusion that we can draw is important: in the big picture of eating more sustainably, picking the best among frozen, canned or glass foods, has a relatively small impact on CO2 emissions.

It makes sense (and we’ve confirmed) that the vegetable with the lowest climate impact is the one that’s local and in season. Outside of their season, the climate impact of fresh veggies depends on where they come from. If they come from the neighbouring country by truck it can have a minimal effect, but if they are transported from far away by plane, it can have quite an impact. In that case frozen, canned or vegetables in glass are good options to increase the diversity and amount of vegetables you eat.

Even though there’s not a grand study comparing these three options, we can say that frozen is the clear winner. Even though freezing vegetables costs energy during production and at your home (which has a climate impact), the impact is lower than food in glass or canned. Besides that, the frozen form also helps us to waste less. We just take out what we need and the rest remains in the freezer.

For some vegetables there are no frozen options, like tomatoes or legumes, so what’s the second best? Canned or in glass? The honest answer is: it depends. It depends on so many factors that we don’t have insight to when we’re standing in front of the supermarket shelf, that it’s impossible to know the right answer. In that case it’s better to let your decision be guided by other factors like whether you want to choose the organic version.

Even more important than choosing the right packaging – as far as this is even possible – is keeping an eye on food waste. For frozen products this is less of an issue, but if you pick a canned vegetable or vegetable in glas, don’t use half of it and store the rest in the fridge. Big chance you’ll throw it out later in the week. Just add some more vegetables to the meal you are cooking!