Upgrading of Mixed Food Industry Side-Streams by Solid-State Fermentation with P. ostreatus

Theodoros Aggelopoulos,Argyro Bekatorou,Poonam Nigam,Athanasios Koutinas,Stavros Plessas

doi:10.3390/recycling3020012

Theodoros Aggelopoulos, Argyro Bekatorou + Show 3 more

Open Access

https://doi.org/10.3390/recycling3020012

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Abstract

In the frame of efforts to exploit agroindustrial side-streams and wastes (AISS) for added-value products that are based on single cell protein (SCP), mixed substrates consisting of brewer’s spent grains (BSG), malt spent rootlets (MSR), cheese whey, molasses, orange, and potato pulps, were used for growth of the edible mushroom Pleurotus ostreatus. The substrates were mixed in various combinations, and were used for P. ostreatus growth at various conditions. The substrate, for which the highest sugar consumption, protein increase, and mycelium yield were observed, consisted of 20 mL molasses (4° Baume density), 20 mL potato pulp, 5 mL whey, 5 mL orange pulp, 30 g BSG, and 5 g MSR (at 25 °C and substrate pH 4). The mycelium-enriched product was analyzed for protein, fat, minerals (Ca, Mg, Fe, Cu), and aroma volatile compounds, indicating the potential for use as nutritious supplement for food, feed, or microbiology uses. The product was also autolyzed, freeze-dried, powdered, and analyzed for total ribonucleic acid content, showing the potential for use as a commercial natural food flavor enhancer.

Highlights

Agro-industrial wastes and side-streams (AISS), which are produced in large amounts worldwide, are usually rich in fermentable components
Single cell protein (SCP) production has been the subject of extensive research mainly for the production of animal feeds that are enriched in protein by microbial treatment of various AISS using both submerged (SmF) and solid-state fermentation (SSF) processes
The sugar, protein, fiber, and mineral content of the sixAISS samples, as well as the presence of minor compounds, such as vitamins and trace elements, makes them suitable for microbial conversion. Previous analysis of these exact substrates showed that brewer’s spent grains (BSG), malt spent rootlets (MSR), and cheese whey had a considerable protein content of about 31, 24, and 14 %w/w, respectively [9]

Summary

Introduction

Agro-industrial wastes and side-streams (AISS), which are produced in large amounts worldwide, are usually rich in fermentable components. Food industry side-streams, such as brewer’s spent grains (BSG) and malt spent rootlets (MSR) from breweries, wasted fruits and vegetables form agricultural production, landfills, restaurant wastes, etc., whey from the dairy industries, and molasses from the sugar industries, have the high potential for biotechnological utilization. Apart from molasses, they are used in limited amounts as livestock feed or are discarded in the environment since their high organic load makes biological treatment impossible [1,2,3,4,5,6,7,8,9,10]. Single cell protein (SCP) production has been the subject of extensive research mainly for the production of animal feeds that are enriched in protein by microbial treatment of various AISS using both submerged (SmF) and solid-state fermentation (SSF) processes. The most common examples of food grade SCP are baker’s, brewer’s, and distiller’s yeasts, as well as food and feed supplements (as protein and vitamin sources and flavor enhancers)

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