Use of faba bean (Vicia faba L.) hulls as substrate for Pleurotus ostreatus – Potential for combined mushroom and feed production

E Ivarsson,M Grudén,J Södergren,M Hultberg

doi:10.1016/j.jclepro.2021.127969

E Ivarsson, M Grudén + Show 2 more

Open Access

https://doi.org/10.1016/j.jclepro.2021.127969

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Abstract

A circular concept involving use of faba bean hulls for production of oyster mushrooms (Pleurotus ostreatus (Jacq.) P. Kumm.) and the post-harvest residues for feed purposes was evaluated. Faba bean hulls are a waste remaining after the beans are dehulled to decrease the content of anti-nutritional factors and increase the food value of the beans. Faba bean hulls proved very suitable as substrate for production of oyster mushrooms, with biological efficiency of 109 ± 28%. The fruiting bodies produced were comparable to commercially sold mushrooms in terms of morphology, protein content, protein quality, and chemical composition. After mushroom harvest, 48.4 ± 0.6% of initial dry weight (dwt) of the substrate remained and showed significant changes in proximate composition, with an increase in protein concentration from 207.9 ± 8.6 to 346.6 ± 16.5 g kg−1 dwt and a significant increase in 14 of 16 amino acids analyzed, including methionine. Concentrations of the anti-nutritional compounds vicine and convicine were below the detection limit after mushroom harvest, while their initial concentration was 5.7 ± 0.1 and 1.4 ± 0.04 g kg−1 dwt, respectively. Tannin concentration was reduced by approximately 50%, to a final level of 9.0 ± 1.6 g kg−1 dwt. Comparison of the spent mushroom substrate with a commonly used feedstuff for pigs indicated potential for the spent substrate to be a valuable protein source in pig diets. This study demonstrates the potential for achieving complete circular use of agro waste and has implications for development of production systems well suited in the biobased society.

Highlights

A change in diet is proposed to help resolve major societal chal lenges, with increasing consumption of legumes identified as a strategy for sustainability in the food system (Roos et al, 2018)
The present study examined the potential for using faba bean hulls as substrate for production of oyster mushrooms
This study demonstrates the potential of using edible wooddegrading mushrooms for valorization of agro-waste, achieving com plete circular use of a waste for production of food and feed

Summary

Introduction

A change in diet is proposed to help resolve major societal chal lenges, with increasing consumption of legumes identified as a strategy for sustainability in the food system (Roos et al, 2018). Production of legumes in Europe is low. Improving the market value of legumes, e.g., by using different types of processing techniques, is a recognized strategy that could promote production (Preissel et al, 2015). As with several other legume crops, there are anti-nutritional factors of concern that impair their nutritional quality. In faba beans, condensed tannins are a major anti-nutritional factor, with the highest concentrations of these substances found in the hull (Sinha and Kumar, 2018; Helsper et al, 1993). Dehulling is an obvious strategy to increase the utility of the beans in different food products

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