How sustainable are plant protein food products?

Illustrative photo from Eat The Future. Photo: Joe Urrutia / FoodProFuture

By Erik Svanes, Department of food and packaging research, Østfoldforskning, WP1 leader

It has been well known for several years that grain legumes have a much lower environmental impact than animal protein, both per kg product and per kg protein. The difference is particularly pronounced when comparing the climate impact of grain legumes with meat from ruminants (beef and mutton), but there are also significant differences for other environmental indicators such as eutrophication, acidification, toxic impacts and use of limited resources such as fossil resources (oil, natural gas, LPG), water and agricultural area.

The main reason for these differences is that a significant amount of energy, protein and other nutrients are “lost” when rearing animals and fish, see figure 1 and 2. We can reduce the loss by e.g. good utilisation of the manure produced and the by-products after slaughter, such as intestines, bones and hides. However, no matter how efficient the production of animals is, eating plants will always be more resource efficient than eating animals.

On the other hand, we cannot make a fair comparison of animal and plant protein without considering what happens after farming. Grain legumes require, in general, more cooking and processing than meat and the protein quality is lower than with meat. In one Swedish study, the energy consumption of the processing of a pea-based product was so high that the whole advantage of using pea instead of chicken was lost, at least in terms of climate change.

In a recent publication (Huesala et al 2020) the effect of processing on the sustainability was compared between oat and faba bean protein concentrates and animal protein concentrates, mostly dairy. Faba bean protein concentrates from dry processing was shown to give rise to 80-90 % less greenhouse gas emissions per kg protein compared to the animal protein equivalents but for oat protein concentrate, the difference was far less, only about 50 %. The reason for oat protein concentrate giving higher greenhouse gas emissions than faba bean concentrate  lies partly in the low protein content of oats, but other factors are also very important:  cereals requires more N fertilizer and that the energy requirements and use of chemicals are much higher in the oat processing  compared to faba bean

Another key factor that must be considered is the utilisation of by-products. It is a waste of resources if the processing gives a high-quality protein concentrate but the major part of the raw material goes to waste or to a low-quality utilisation. This is what mostly happens for meat and fish. Often only 40-50 % of the animal or fish is used for human consumption and the rest goes to lower value utilisation. Some is eaten but a large proportion is used for feed for pets or fur animals and some is used for energy purposes or fertilizer.  But, the possibilities for using by-products from grain legumes in food products seems to be much better than for meat and seafood. For example, it is easier to use a faba bean starch fraction for food than bones from animals.

Pea starch and protein fractions, as well as spaghetti extrusion prototypes. Photo: Nofima / FoodProFuture

In the life cycle assessment methodology, we distribute environmental impacts between different products and by-products using a method called allocation. There are several ways of allocating impact to several products, but generally when the products have very different value, “economic allocation” is preferred. Using this method, we distribute impacts between products using the economic value as distribution principle.

To illustrate this example, I will give one example: If there are two products from one raw material, and product A earns 90 % of the total income per kg raw material and product B only earns 10 %, then product A is allocated 90% of the environmental impact. The idea is that the price reflects the nutritional and sensorial (and other quality parameters) value of the product. The producer will always try to maximize profit by getting as high price as possible for the products. Thus, we can see that the producer’s decisions, including those that regard environmental impacts, is guided by a profit motive. Thus, economic allocation is justified, because it follows the producer’s way of thinking. At the same time, it encourages efficient resource use.

Using economic allocation has several important implications. One is that the environmental impact of the main product depends a lot on the value of the co-products/by-products. Thus, the processing has a large impact on the environmental impact of the by-products. In the case of grain legumes, there will often be a main protein-rich fraction and one or several other fractions. We want to have a high yield of the main product, e.g. protein concentrate with high protein content and high quality, but the quality of the by-products is just as important.


Products and intermediate products from peas and faba beans grown in Norway

In FoodProFuture, the decision was made to go for dry processing. As indicated by Huesala et al and other studies this is a good environmental choice. We have performed life cycle assessments (LCA) of faba bean concentrates and pea concentrates in Norway and of the respective starch fractions. The starch fractions are the “leftover” after the protein fractions have been removed.

The results have been compared to LCA results for the “average” protein we eat in Norway today. These “average”  protein results we call the “baseline” results. It has been a huge undertaking requiring a lot of effort to calculate these numbers. First the average food we eat was mapped. Then 21 separate LCAs, many of them covering large and complicated product systems, were calculated using identical methodology. The results were combined to give an average impact per kg product. In addition, calculations were made showing impact per kg protein. Results are given in the report “Life Cycle Assessment of the existing protein consumption in Norway” (Svanes E, Report OR45.19, Østfoldforskning).

The impacts between the pea and faba beans as raw material and as intermediate product, and of the average protein consumed in Norway, are shown in the tables and figures below.

From the results the impact of pea and faba bean concentrate is far less than the protein we eat today. Going into the details of the different product groups, we can see that not only are these plant protein fractions better than beef and mutton, but they are also better than pork, chicken, dairy products, seafood and eggs. When comparing with liquid dairy products pr kg, the picture is not so clear, but this is an unfair comparison. Most dairy products are liquid and as such contains much less nutrition pr kg than solid plant protein products. When we compare per kg protein, we see that plant protein outperforms dairy products. However, the pea and faba bean concentrate need to be processed into food products, they are not consumed as they are. The results from Huesala shows that even when heavy processing is used, emissions of greenhouse gas emissions  would still be much lower than for the average protein consumed or animal protein products.

These findings have several implications. The first major implication is that animal protein is not just a climate issue. For almost all environmental impact categories , the plant protein outperforms the animal protein. One example is use of fossil fuels. On average, the protein we eat requires 3 kg “oil” (to be precise it is oil equivalents) while plant protein only requires 0,1-0,4 kg “oil”. For ecotoxicity however, the difference between plant protein and the average consumption is much smaller, but plant protein is still much better in most cases.

The other implication is that even though peas and faba beans require more processing, they are still environmentally better than the protein we currently consume. But, as demonstrated in the study of Heusala et al, the difference is much less when plant protein is “wet” processed. Thus, it is still possible to “process away” much of the advantage that plant protein has over animal protein.

The major lesson we can learn is that large environmental gains can be made if the consumption of animal protein could be reduced and consumption of plant proteins increased. The benefit will probably increase as processing technology advances to give high quality products in high yield.


Finished products from peas

We have focused the research on legumes as unprocessed raw material and as processed intermediate products, but what is the impact of  a ready to eat product? Two products have been studied: Beyond Burger made from pea protein isolate, and a pea burger made from unprocessed peas. The results are given in table 3. Beyond Burger has an impact 2-5 times lower than that of the average protein food product pr kg protein, and the pea burger has an even lower impact. It must be noted that this is a conservative estimate, since all impacts of the average protein consumed after initial processing are not included. These impacts include, for meat, production of (e.g.) a hamburger,  packaging and distribution retail and consumer impacts, including the effects of food waste. Calculating all these impacts is not practically possible, as there are so many products made from these raw materials.

The calculations again illustrate the importance of processing. Beyond Burger is made from pea protein isolate, a product of a wet process while the other product comes from dry processing. These results show that the plant protein product is environmentally better than the average protein consumed, and much better than meat. The benefit is much bigger if unprocessed or dry processed legumes are used in the product, than if wet-processed legumes are used.

The exact recipe of Beyond Burger is unknown, hence this result is more uncertain than the other results. However, the climate impact is close to the result reported by the company who produces this product.


Unprocessed beans and peas

Peas and faba beans can, of course also be eaten unprocessed, but they must be boiled before use. They can be cooked in the food industry and sold to consumers. They can also be sold dry, as pure raw material, and then boiled by consumers.

The impact of the boiling process has been calculated. Assuming that electricity is used for boiling, using the Norwegian grid electricity and assuming that the heat for boiling is not contributing to the heating of the building the impact is small. We assume 2 hours boiling, but this could be reduced drastically by using a pressure cooker. The climate impact we found from cooking was only 9 g CO2-eq pr kg legume, while the Cumulative energy demand is 2,6 MJ.  This is negligible when compared to the other impacts in the value chain.

This means that the impact of unprocessed grain legumes is also a good environmental option, at least in Norway where electricity is so “green”. In other countries, the impact of electricity production can be quite high, e.g. in Poland where coal is used. In such cases, boiling legumes on an electric stove would give rise to much higher emissions, e.g. a climate impact of 0,35 kg CO2-eq/kg legume.

Whole faba beans. Photo: FoodProFuture

We do not have the whole picture

The implication of the findings of this study would seem to be a strong recommendation to produce as much plant protein as possible and reduce the production of red and processed meat.

One implication would be that we could reduce the amount of soybeans Norway imports for feed. Instead of importing soybeans for feed, we could instead use these soybeans directly in food. Or we could import some other food legume. This would have enabled a further reduction in meat production without reducing the national self-sufficiency. The effect of national self-sufficiency is not clear and must be studied further.

The question of national self-sufficiency illustrates the point that the results given here do not give a full overview of all sustainability impacts that such a transition would cause.

A strong reduction in meat production would mean a large reduction in employment, mainly in rural areas with little or no alternative employment possibilities. It would probably result in many people having to move, leaving some areas more or less unpopulated, which is against the political goal of keeping the whole country populated. The new jobs created would be in areas around the Oslo fjord, which is already densely populated, compared to many other parts of the country.

The use of renewable resources is another argument that must be considered. A lot of the country is grass-covered, and this grass can only be used for food if ruminant eats it. Similarly, wild fish eat foods we cannot ourselves eat, such as plankton. The country is well suited for meat and dairy production and we have large fish stocks that can be sustainably harvested. Other factor that must be considered are the high biodiversity in some pastures, the aesthetic value of keeping landscapes open through grazing and social sustainability of the production.

One of the most important impacts of a partial shift from animal to plant protein is health. This is a very important effect that must be considered when looking at total impacts.

Further research

In Work Package 1, research is ongoing. In one part of the study, the impact of realizing the full potential to increase plant protein production in Norway, consuming these products in Norway and replacing animal protein, is studied. Environmental impacts such as climate impact will be studied, but in addition, impacts on national self-sufficiency and on agricultural areas both in Norway and abroad will be investigated.

In another part of the project, the effect of behaviour and attitudes to diet and subsequently environmental impact have been studied for segments of the Norwegian population, It is expected that this research will give more insight into why consumers choose to eat what they do and what can be done to change or reinforce their behaviour.