Abstract
This study assessed the functional profile (foaming, emulsifying and rheological properties), proteomic and metabolomic composition of a naturally foaming and currently unexploited co-product (centrate) from the Quorn fermentation process. Due to the low environmental footprint of this process the centrate is a potential source of sustainable functional ingredients for the food industry. A range of fractions were isolated from the centrate via successive ultrafiltration steps. The retentate 100 (R100) fraction, which was obtained following a 100 kDa ultrafiltration, displayed good foaming, emulsifying and rheological properties. R100 solutions and oil-in-water emulsions displayed high viscosity, while R100 solutions and hydrogels showed high viscoelasticity. R100 foams displayed high stability while oil-in-water R100 emulsions showed small and stable oil droplet size distributions. Large mycelial aggregates were reported in R100 solutions and gels, correlating with their high viscosity and viscoelasticity. A dense mycelial network was observed in R100 foams and contributing to their stability. In parallel tensiometry measurements highlighted the presence of interfacially active molecules in R100 which formed a rigid film stabilising the oil/water interface. A number of functional metabolites and proteins were identified in the centrate, including a cerato-platanin protein, cell membrane constituents (phospholipids, sterols, glycosphingolipids, sphingomyelins), cell wall constituents (chitin, chitosan, proteins), guanine and guanine-based nucleosides and nucleotides. This study highlighted the potential of functional extracts from the Quorn fermentation process as novel ingredients for the preparation of sustainable food products and the complex and specific nature of the centrate’s functional profile, with contributions reported for both mycelial structures and interfacially active molecules.Graphical abstract
Highlights
Animal-derived functional ingredients including milk and egg proteins play a key role in the food industry due to their ability to form gels and to stabilise oil droplets in emulsions and air bubbles in foams
The rationale behind using the whole centrate stream for ultrafiltration instead of its centrifugation supernatant was based on an initial functional comparison between the two samples, during which the whole centrate showed higher foaming and emulsifying properties than its supernatant
Fungal cell and mycelial debris were observed in the centrate and retentate 100 (R100) + 5 solutions (Fig. 1a, c), with the characteristic mycelial network of the Quorn fermentation broth centrifugation deposit chosen as reference (Fig. 1d)
Summary
Animal-derived functional ingredients including milk and egg proteins play a key role in the food industry due to their ability to form gels and to stabilise oil droplets in emulsions and air bubbles in foams. Due to their high environmental costs and market volatility, the food industry is looking for sustainable alternatives [1]. One of the strategies employed consists in screening unexploited co-product streams from the food industry for extraction of potential functional alternatives In this context the production of fungal proteins by Marlow Foods for use in their meat alternative product Quorn is a potential source of sustainable functional ingredients. The fermentation of starch into protein by F. venenatum results in 90% lower emission of greenhouse gases and benefits in terms of land and water footprints in comparison with beef products [4]
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