Exploring the circular economy potential of larval fat for animal and human food


The majority of dietary fat in the human diet comes from animal products. Yet animal agriculture is responsible for 14.5% of all anthropogenic greenhouse gas (GHG) emissions and is therefore often not considered the most sustainable option.

At the same time, humans do not consume enough fat. Recent research in Sweden has calculated that the average fat intake in many populated areas of the world is below dietary guidelines.

These same researchers estimate that for the world’s population to reach recommended levels of fat consumption, an additional 45 million tons of dietary fat must be produced and consumed.

Given the history of deforestation from cattle, palm and soybean production, among other irresponsible and unethical practices, researchers are looking for alternative ways to increase fat production and consumption, in a sustainable way.

Circular economy potential

A separate group of researchers in Sweden, working at the Swedish University of Agricultural Sciences in Uppsala, is addressing this issue from a waste management perspective.

Globally, organic waste accounts for about 3-5% of total anthropogenic GHG emissions due to food scraps dumped in landfills. Yet, in a true circular economy, there should be zero waste, including food waste.

“The lateral flow of one process should be used as a new process in another”, ​Cecilia Lalander, an associate professor of environmental engineering in the university’s Department of Energy and Technology, explained at a recent TABLE event.

In Lalander’s native Sweden, this does not happen. Sixty percent of the country’s food waste is incinerated, with the excess heat generated by the process used for district heating. Overall, the situation is much worse, Lalander pointed out: “Most organic waste goes to landfill.”

The researchers believe they have found a potential solution that could increase sustainable fat production while reducing GHG emissions from discarded food waste. The solution, Lalander explained at the event, lies in insect fat.

Regulatory challenges

The researcher proposes that the mixed food waste be fed to insects, and that these insects be fed to animals for human consumption.

Perhaps the most obvious solution would be to feed the mixed food waste directly to the animals. However, this practice is prohibited in Europe. “It’s allowed in many parts of the world, but hasn’t been allowed in Europe since the mad cow disease of the 80s and 90s,” explained Lalander.

And in fact, insects are also classified as farm animals. This means that under EU law insects cannot be fed mixed food waste either.

But, as Lalander explained at the TABLE event – ​​coordinated by the University of Oxford, the Swedish University of Agricultural Sciences and Wageningen University and Research – by donating mixed food waste to insects, then by feeding these insects to animals, an additional “safety barrier” is created before human consumption.

“We want to recycle complex molecules, like amino and fatty acids, but we don’t want to recycle [potential] pathogenic microorganisms. So we’re trying to…design a natural process where we raise fly larvae out of food waste so they can be used for animal production.

Specifically, the project focuses on black soldier fly larvae, which can grow from 1 mg to 200 mg in a fortnight. “They have a 200-fold increase in body weight over the two-week process.”

Could insects contain more fat than protein?

So just how efficient is black soldier fly larvae production when fed food scraps? According to the researchers’ calculations, one ton of food waste can feed 250 kg of fly larvae, which is equivalent to about 35 kg of crude protein and 30 kg of crude fat.

The fatty acid composition changes depending on the type of food waste used to feed the larvae. The smallest amount of fat is produced by feeding mussel insects, followed by salmon and mixed food scraps.

The predominant fatty acid type was found to be saturated fatty acids, followed by monounsaturated fatty acids, with a lower proportion of polyunsaturated fats.

Most of the fats were present in bread-fed larvae. “Fat content varies quite dramatically depending on what they were raised on, and what is striking is that a very high carbohydrate diet will result in very fat larvae,” explained the researcher.

“These larvae can have a fat content of up to about 50% on a dry matter basis,” Lalander said, suggesting the larvae may contain more fat than protein.

It was particularly interesting to note that most of the fat in the larvae was synthesized by the larvae, meaning that they produced it themselves rather than getting it from their diet.

From a sustainability perspective, using insects as a protein feed has proven to have a higher environmental impact than most common feeds used today, such as chicken feed, fishmeal and generic protein foods.

However, if the insects were fed mixed food waste, then the insect feed would have a negative impact on the environment, the researcher explained: “That means it’s positive for the environment, so we really have to consider what we’re feeding the insects.”

Insect fat for human consumption

Lalander suggested that further research could investigate the environmental impact of farming insects for fat production, rather than protein, as well as exploring the potential animal health benefits of insect fat consumption. .

Another pressing question is whether insect fat could be used directly for human consumption.

The researcher expressed concerns about consumer acceptance of insect-based products. “I think it’s a question of social acceptance” we have been told. Flavor, Lalander suggested, is another potential issue: “They’re not super tasty.”

However, insects could be further transformed to become “further away” from their original form, as is currently being done for some varieties of insect protein. But the fact remains that European legislation prohibits feeding insects with mixed food waste, and therefore “currently, it’s rather no-no”.

It’s unclear whether such regulations may change in the future, but Lalander is hopeful. “We are [seeing] one exemption after another to this legislation, so yes, I think that will definitely happen.

Source: The Planetary Health of the Lancet
“The role of fats in the transition to sustainable diets”
Posted on September 8, 2021
DOI: https://doi.org/10.1016/S2542-5196(21)00194-7
Authors: Bojana Bajželj, Federica Laguzzi. Elin Röös

Source: Waste Management
‘Fatty acid composition of the larvae of the black soldier fly (hermetia illucens) – Possibilities and limits of modification by food
Posted on October 23, 2019
DOI: https://doi.org/10.1016/j.wasman.2019.10.014
Authors: Nils Ewald, Aleksandar Vidakovic, Markus Langeland, Anders Kiessling, Sabine Samples, Cecilia Lalander


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