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Solid fermentation of agri-food co-products: analysis of environmental benefits

Published on November 02, 2022


The ancestral technique of fermentation appears today as one of the possible ways to respond to certain food and environmental issues. In particular, solid fermentation could be a lever to better valorize agri-food co-products. In this context, INRAE scientists have used a life cycle assessment method to evaluate the environmental impact of this technology. Pioneering results, published on October 31 in Nature Food.

In France, agri-food co-products are very little reused for human food. Their main use, up to 60%, is for livestock feed.

The potential of this resource is far from being fully exploited. It is therefore necessary to activate levers. Fermentation, especially in solid medium, is one of the ways of valorisation that is emerging.

Just like the classic liquid fermentation, in yogurt for example, solid fermentation relies on the colonization of a medium by microbes. But under what conditions does it generate environmental benefits 

To answer this question, INRAE scientists applied a "cradle-to-grave" life cycle assessment (LCA) to six co-products from different processing industries representative of production in mainland France. The environmental impact of their recovery by solid fermentation was compared to that of other recovery methods, such as their direct use in livestock rations or their transformation into energy. The impact on climate change, land use and water resources, marine and freshwater eutrophication, were then quantified.

Contrasting results, depending on the co-products and uses. If it is possible, the use of solid fermentation for human consumption allows a clear reduction of greenhouse gas emissions. It also allows the safeguarding of arable land and fresh water resources. Concerning the valorization for animal feed (after solid fermentation), it does not bring a strong environmental benefit, given the important energy contributions which exceed the benefits brought by the nutritional improvement. In terms of reducing the effects of climate change, the best option is the direct inclusion of co-products in animal rations. For co-products of low nutritional value, energy recovery, here via la production de biogaz par digestion anaérobique s’est avérée la meilleure option.

These initial results illustrate the advantages and disadvantages of new biomass valorization techniques, particularly those aimed at formulating new foods and ingredients. At a time when more and more competitive uses of bioresources are emerging, the implementation of standardized LCAs adapted to new value chains would allow their integration into the decision-making toolbox.


Javourez, U., Rosero Delgado, E.A. & Hamelin, L. Upgrading agrifood co-products via solid fermentation yields environmental benefits under specific conditions only. Nat Food (2022).

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