Vegetable protein needs more energy efficient processing, says study
There has been considerable discussion in recent times as to how a reduction in meat consumption could help improve the environmental footprint of the food system. Previous studies have reckoned that 18 per cent of global green house gas emissions come from animal husbandry alone. When all stages in the food production are taken into consideration, the emissions contribution would be higher still.
The new study, conduced by researchers from the Swedish Institute for Food and Biotechnology and Switzerland’s Agroscope Reckenholz-Tänikon Research Station, set out to compare the environmental impacts of four meals with different protein sources, in two different countries – Spain and Sweden.
They found that, while a meal made with 100 per cent vegetable protein did make a smaller impact on the environment in some respects, they required about the same energy as meals made with animal proteins.
“Peas can be considered ‘green’, but there remains a significant need for more energy-efficient processing of vegetarian products,” they wrote in an article to be published in Food Research International.
Four meals, two countries
The four meals included in the study were as follows:
- A ‘soy’ pork chop, from a pig fed on conventional imported soy and cereals.
- A ‘pea’ pork chop from a pig that are feed based on peas, rape seed and cereals grown mostly in Europe.
- A sausage ‘partial pea’, in which 10 per cent of the meat was replaced by pea protein and the pork was produced from ‘pea’ feed as above.
- A ‘pea’ burger, where all the meat in the burger was replace by Europe-grown peas.
All the meals were served with potatoes, raw tomatoes, wheat bread and water.
The peas, pork, wheat and potatoes for the Spanish meal were produced in Spain, whereas for the Swedish meal they were produced in Germany (except the potatoes, which came from Sweden).
In Spain the potatoes were roasted in the oven; in Sweden they were boiled. The chops, sausages and burgers were fried in a frying pan in both countries.
The Spanish meal was also served with 300ml of mineral water, served from a 1.5l bottle.
The team were not interested in comparing the two countries so much as showing how the results and potential for improvement depend on the surroundings and culture.
The researchers used the life cycle assessment (LCA) method. They looked at raw material production in agriculture, including production of inputs like fuel and fertiliser; packaging material inputs and waste management of used packaging; production of electricity, heat and water; electricity for cooking and storage in households; and all transport.
Findings
The researchers found that the energy use for all four meals was “in the same order of magnitude”.
In the Spanish case, energy use was higher because the potatoes were roasted rather than boiled. The contribution from the pig farm was also higher in Spain, and the plastic from the mineral water bottle had to be taken into consideration.
Other environmental parameters yielded better results for the pea burger however. It made the smallest contribution to global warming, while the sausage made the highest. The two pork chops made equal contributions.
Again, the pea burger performed better in terms of eutrophication than the meat protein meals.
Subbing some of the animal protein for pea protein was deemed to be beneficial only if more than 10 per cent is replaced.
“This study also demonstrates that the environmental impact does not differ much between meats produced with different feed protein sources. Another conclusion is that the energy source (eg electricity production) plays an important role in the environmental impact of the meals,” wrote the researchers.
Source
Food Research International
DOI: 10.1016/j.foodres.2009.08.017
“Environmental impact of four meals with different protein sources: Case studies in Spain and Sweden.”
Authors: Davis, J; Sonesson, U; Baumgartner, D; Nemecek, T.
