Boosting Nutritional Value of Olive and Walnut Waste Using Mushroom Fermentation

Jenn Hoskins
12th June, 2024

Boosting Nutritional Value of Olive and Walnut Waste Using Mushroom Fermentation

The oyster mushroom, Pleurotus ostreatus, effectively transforms low-value agricultural waste from olive and walnut processing into a protein-enriched animal feed supplement via solid-state fermentation.

Public Domain Photograph

Key Findings

  • The study by the Hellenic Agricultural Organization - DIMITRA focused on transforming olive mill stone waste (OMSW) and walnut shell (WS) into protein-enriched animal feed
  • A mixture of 80% WS and 20% OMSW resulted in the highest protein increase, boosting protein content by 69.35% to 7.57% of its mass
  • This mixture also reduced lignin content by 26.13% and tripled the amount of beneficial β-glucans to 6.94% of the substrate's mass
Agro-industrial by-products, such as olive mill stone waste (OMSW) and walnut shell (WS), pose significant environmental and economic challenges due to their abundance and disposal issues. Recent research conducted by the Hellenic Agricultural Organization - DIMITRA has focused on transforming these by-products into protein-enriched animal feed using solid-state fermentation (SSF)[1]. This study aims to address the scarcity of proteinaceous animal feed while also reducing the environmental footprint of agro-industrial processes. The study utilized various mixtures of OMSW and WS as substrates for the SSF process, initiated by the fungus Pleurotus ostreatus. The findings revealed that a substrate composed of 80% WS and 20% OMSW resulted in the highest increase in protein content, accounting for 7.57% of its mass, which represents a 69.35% increase. Additionally, there was a 26.13% reduction in lignin content, and a three-fold increase in 1,3-1,6 β-glucans, reaching 6.94% of the substrate's mass. These results highlight the potential of OMSW and WS mixtures to serve as efficient substrates for developing novel protein-rich animal feed supplements. Previous studies have shown the potential of SSF in converting agro-industrial wastes into valuable products. For instance, the bioconversion of OMSW with oat bran (OB) and Lathyrus clymenum pericarp (LP) using SSF initiated by Pleurotus ostreatus resulted in significant increases in protein content and β-glucans, along with reductions in lignin content[2]. These findings align with the current study, demonstrating the effectiveness of SSF in enhancing the nutritional value of agro-industrial by-products. Agro-industrial waste is rich in nutrients and supports microbial growth, making it a suitable substrate for fermentation processes. Lignocellulosic agricultural residues, which are primarily composed of carbohydrates, have been extensively studied for enzyme production using SSF. The physical-chemical nature of lignocellulosic substrates lends itself to solid-phase culture, making SSF a promising method for utilizing agro-based wastes for enzyme production[3]. The current study builds on these findings by demonstrating the potential of OMSW and WS mixtures to act as efficient substrates for SSF, resulting in protein-enriched animal feed. The use of P. ostreatus fungus plays a crucial role in this process, as its secreted enzymes facilitate the degradation of the substrates, leading to increased protein content and reduced lignin levels. This aligns with previous research that has highlighted the role of microbial fermentation in converting agri-food wastes into value-added products[4]. In summary, the study conducted by the Hellenic Agricultural Organization - DIMITRA provides a promising solution to the problem of proteinaceous animal feed scarcity and the environmental impact of agro-industrial processes. By utilizing SSF to transform OMSW and WS into protein-enriched animal feed, the study contributes to the circular economy by promoting the reuse of agro-industrial by-products. This research not only addresses the need for sustainable animal feed but also offers a method to reduce the environmental footprint of agro-industrial activities.

NutritionSustainabilityMycology

References

Main Study

1) Nutritional upgrade of olive mill stone waste, walnut shell and their mixtures by applying solid state fermentation initiated by Pleurotus ostreatus.

Published 11th June, 2024

https://doi.org/10.1038/s41598-024-64470-1

Related Studies

2) Transformation of mixtures of olive mill stone waste and oat bran or Lathyrus clymenum pericarps into high added value products using solid state fermentation.

https://doi.org/10.1016/j.wasman.2022.06.018

3) A Review on Bioconversion of Agro-Industrial Wastes to Industrially Important Enzymes.

https://doi.org/10.3390/bioengineering5040093

4) Fermentation of Agri-Food Waste: A Promising Route for the Production of Aroma Compounds.

https://doi.org/10.3390/foods10040707


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