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From surplus bread to burger using filamentous fungi at bakeries: Techno-economical evaluation
University of Borås, Faculty of Textiles, Engineering and Business.ORCID iD: 0000-0002-0923-1097
University of Borås, Faculty of Textiles, Engineering and Business.ORCID iD: 0000-0003-3418-1762
University of Borås, Faculty of Textiles, Engineering and Business.ORCID iD: 0000-0003-4887-2433
2021 (English)In: Cleaner Environmental Systems, ISSN 2666-7894, Vol. 2Article in journal (Refereed) Published
Sustainable development
According to the author(s), the content of this publication falls within the area of sustainable development.
Abstract [en]

A novel approach of utilizing unsold bread at bakeries as a substrate for the fermentative production of a fungal food product have been developed. Techno-economic feasibility of implementing on-site solid-state fermentation in small-scale bakeries in Sweden to recover 10 kg/day surplus bread using the edible fungus Neurospora intermedia was investigated. Different inoculation to substrate ratios were compared, where 24% of fermented solids to inoculate the next batch presented the best fermentation-benefit ratio. Total capital cost was at its maximum €12,600 that can process 70 tons bread (10 kg/day) in its 20-years lifetime to produce 63 tons of product. Operational costs were dominated by labour cost (53%). Outcomes indicate that the process implementation is economically feasible with an annual net profit of €62,000, rate of return on investment of 18.5%, with a payback-period of 4 years at a discount rate of 7%. According to sensitivity analysis, product-selling price and process bread capacity were critical to the process's economics. Increasing the capacity to 100 kg/day resulted in a substantial increase in net profit value of €5,700,000 compared to the base case scenario. Implementation of this process cast insights on techno-economic performance of a sustainable treatment for surplus bread at bakery-level.

Place, publisher, year, edition, pages
Elsevier, 2021. Vol. 2
Keywords [en]
Techno-economic analysis, Edible filamentous fungi, Solid-state fermentation, Value-added products, Waste management, Resource recovery
National Category
Food Science
Research subject
Resource Recovery
Identifiers
URN: urn:nbn:se:hb:diva-25501DOI: 10.1016/j.cesys.2021.100020ISI: 000828614800018Scopus ID: 2-s2.0-85114673345OAI: oai:DiVA.org:hb-25501DiVA, id: diva2:1562508
Funder
Swedish Agency for Economic and Regional Growth, 20201656Available from: 2021-06-08 Created: 2021-06-08 Last updated: 2024-02-01Bibliographically approved
In thesis
1. Circular bioeconomy through valorisation of agro-industrial residues by the edible filamentous fungus Neurospora intermedia
Open this publication in new window or tab >>Circular bioeconomy through valorisation of agro-industrial residues by the edible filamentous fungus Neurospora intermedia
2021 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Prevention of dramatic climate change and ensuring food and nutrition security for subsequent generations necessitates the reduction of greenhouse gas emissions and efficient use of the world’s resources, including efficient waste disposal. The agro-industrial sector generates a large amount of organic waste, that is currently underexploited owing to poor waste management practices. The circular bioeconomy model is expected to play an important role in the transition towards a sustainable future, and a group of microorganisms known as fungi can be part of the solution, owing to their ability to convert organic waste into useful products, including both materials and energy. These processes hold great potential to change waste materials into resources, leading to societal and environmental benefits. The versatility of various fungi, including their ability to grow in both submerged and solid states, enables the valorisation of liquid and solid streams such as ethanol plant residues ‘thin stillage’ and surplus bread. However, fungal strains need to produce marketable products and exhibit good growth characteristics to be considered suitable for industrial applications. An interesting candidate is the edible filamentous fungus Neurospora intermedia. This fast-growing fungus is able to grow on a wide array of substrates, in both liquid and solid states, and produce industrially relevant products, including its own nutrient rich fungal biomass and carotenoid pigments. 

Submerged fermentation by N. intermedia in semi-synthetic medium showed that the formation of carotenoids can be enhanced by modulating various factors such as light, low pH, high aeration, and the addition of Mg2+ and Mn2+. When cultivated in thin stillage, 6.3 g/L ethanol was produced, along with protein-rich fungal biomass with potential application as feed. However, an additional step was needed to promote pigment production in the fungal biomass. 

Inspired by the traditional use of N. intermedia for food production by solid-state cultivation, the fungal biomass obtained from cultivation in thin stillage was used as inoculum in a subsequent solid-state fermentation step on surplus bread. The fungal product obtained contained up to 33% proteins and 1.2 mg carotenoids/g total material dry weight. By further combining bread as substrate with brewer’s spent grain, a nutrient-rich fungal-fermented product with an attractive texture was successfully produced. The solid-state cultivation resulted in an improved ratio of essential amino acids, and an increase in dietary fibre, minerals, and vitamins, that added further value to the product. To scale up the process, a novel plug-flow bioreactor was developed and successfully operated semi-continuously, without the addition of an external inoculum. Furthermore, a techno-economic feasibility study of on-site solid-state fermentation in small-scale bakeries revealed that the implementation of this process to sustainably use surplus bread at bakery level is economically feasible. 

These studies lay the foundation for the development of N. intermedia as a tool to convert waste material into useful products, contributing to a fossil fuel-free future with positive impacts on the economy.

Place, publisher, year, edition, pages
Borås: Högskolan i Borås, 2021
Series
Skrifter från Högskolan i Borås, ISSN 0280-381X ; 122
Keywords
Neurospora intermedia, mycoprotein, carotenoids, feed, solid-state fermentation, circular bioeconomy
National Category
Environmental Biotechnology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-25692 (URN)978-91-89271-35-7 (ISBN)978-91-89271-36-4 (ISBN)
Public defence
2021-09-10, C203, Allégatan 1, Borås, 10:00 (English)
Opponent
Supervisors
Available from: 2021-08-16 Created: 2021-06-29 Last updated: 2021-08-16Bibliographically approved

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Publisher's full textScopushttps://www.sciencedirect.com/science/article/pii/S266678942100012X

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Gmoser, RebeccaLennartsson, Patrik R.Taherzadeh, Mohammad J

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