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Closing the nutrient loop

Sensemaking / Closing the nutrient loop

The more processes between initial nutrient capture and a human eating them, the more nutrients are lost. Therefore, nutrients are classed as underutilised if they are used lower down the nutrient hierarchy than is possible

By Helen Hughes / 12 May 2016

Recently, there has been a flurry of interest in food waste, for good reason. Currently, 1.3 billion tonnes of food is wasted throughout supply chains every year- roughly 1/3 of what is produced. In a world where millions go hungry, populations continue to grow and climate change threatens harvests, this must be stopped in order to feed everybody. There have been various projects aimed at supermarket and consumer waste. Supermarkets are sending surplus stock to food banks, selling wonky vegetables to reduce waste on farms and providing recipes to help people use up leftovers. This is fantastic progress- in one corner of the supply chain.

In reality, there are nutrients lost through the whole food system where prevention is not an option: when potatoes are processed into ready-to-eat chips, mash or meals, skins and fluids are a by-product. When beer is made, the grain material is left behind. When carrots are harvested, the leaves aren’t required in supermarkets. Valuable nutrients are left behind as by-products of processing. Even manure from livestock contains leftover nutrients. Scientific and technological developments mean that ways to utilise and optimise these nutrient streams are becoming possible, viable and competitive. The food system is colossal, complex and competitive- a challenging structure to tackle, but with huge potential for change. The Protein Challenge 2040 will work on enabling progress in this area, aiming to boost available protein nutrients (read more about the whole Protein Challenge here).


Image credit: Food Waste Reduction Alliance

The more processes between initial nutrient capture and a human eating them, the more nutrients are diluted and lost. Therefore, nutrients are classed as wasted or underutilised if they are being used lower down the nutrient hierarchy (pictured) than is possible. For example, instead of using a by-product as compost to grow crops to feed animals, the by-product could be fed directly to animals. Below are some examples of interventions in current nutrient streams that help to increase the protein available to humans.


Type: Feed

What? Bacteria- consuming underutilised nutrients from food/beverage processors


Type: Feed and Food

What? Insects- fed on byproducts and food waste


Type: Food

What? Protein bars- made from brewery waste

Trial: Closed Loop Fish

Type: Feed

What? Algae- grown on nutrients from dairy shed effluent used to feed wild fish

AFC Yeast

Type: Food

What? Yeast- manufactured as a co-product in ethanol production


Type: Food

What? Chickpea water- can be used as vegan egg/cream alternative

Pacific Ag

Type: Feed

What? Crop leftovers- their use is also beneficial for soil health

Image header credit: maldoit / Flickr

What might the implications of this be? What related articles have you seen?

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