Available online 25 January 2023

Author links open overlay panelAbstract

Oilseed cakes (OC) present high potential as feedstock for the biobased industry. Biotechnological processes allow OC valorization by the production of diverse value-added products and simultaneously altering OC structure, improving their nutritional value, and boosting OC utilization in animal feed. This work explored the use of fungi consortium of two different species as a bioprocessing approach to improve the nutritional quality of OC, obtain enzymes and antioxidants by solid-state fermentation (SSF) of sunflower cake (SFC) and rapeseed cake (RSC). Rhyzopus oryzae and Aspergillus ibericus consortium led to the highest production of cellulase (135 U/g) and β-glucosidase (265 U/g) while maximum protease (228 U/g) was obtained with A. niger and R. oryzae consortium. Maximum xylanase production (886 U/g) was observed in SSF of RSC resulting in high hemicellulose reduction. The synergistic action of lignocellulosic enzymes resulted in fermented extracts with increased antioxidant potential with possible application as food additives against oxidative stress.

Section snippets1. Introduction

Lignocellulosic biomass is a widely bioavailable, natural, and promising material that has been exploited in many biotechnological processes. Biomass is obtained from atmospheric carbon dioxide (CO2) and water, using sunlight as the energy source for the photosynthesis process (Yousuf et al., 2020). Agricultural wastes, industrial by-products, woody materials, energy crops, and human waste are some of the potential sources of lignocellulosic biomass. Global lignocellulosic biomass production

2.1. Oilseed Cakes

Two OC from vegetable oils production industries were used: SFC and RSC. OC were obtained from industries operating in Portugal. SFC was provided by Sorgal, S.A. and RSC was provided by IBEROL – Sociedade Ibérica de Oleaginosas, SARL. OC were dried at 65ºC for 24 hours and kept in closed containers in the dark at room temperature. These OC were previously characterized (Sousa et al., 2021), having both around 40% (w/w) of protein content, 8% of lignin, with slight differences in cellulose (14%

3.1. Enzymes produced by SSF

Compared to single cultures, the use of fungal consortia is an interesting approach for OC bioprocessing due to the production of different enzymes by different species with concomitant impacts on the obtention of other bioproducts and on the final composition of the bioprocessed OC. In this work, three filamentous fungi, R. oryzae, A. ibericus, and A. niger, were selected to explore the effect of using different fungal consortia of two species in SSF of two different OC, SFC and RSC.

The enzyme

4. Conclusions

Synergistic interactions between fungal species in SSF were demonstrated, resulting in an increased performance to produce enzyme rich extracts with an additional property that is their high antioxidant potential, with great interest for many applications such as feed, food, cosmetics, and pharmaceutical industries. Additionally, despite the action of lignocellulosic enzymes produced by fungal consortia was mainly reflected on hemicellulose reduction, fermented OC fibrous fractions are within

Conflict of Interest

The authors confirm that they have no conflicts of interest concerning the work described in this manuscript.

Acknowledgments

The authors thank the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/BIO/04469/2020 and UIDB/04033/2020 units.

Daniel Sousa acknowledges the financial support provided by national funds through FCT (PD/BD/135328/2017), under the Doctoral Program “Agricultural Production Chains – from fork to farm” (PD/00122/2012) and from the European Social Funds and the Regional Operational Programme Norte 2020.

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