Upcycling of food industry side streams by basidiomycetes for production of a vegan protein source

Abstract

Purpose Novel protein sources are urgently needed to meet the increasing protein demand of a continuously growing world population. This study is focused on the production of protein rich mushroom mycelia on industrial side streams. Methods Submerged propagation of mushrooms was carried out in shake flasks which contained agro-industrial side streams as the sole carbon source. The biomass obtained was analyzed for its crude protein, ash and fat content as well as for its fatty acid and amino acid profiles. Vitamin D 2 production from ergosterol in the biomass was induced by UV-B irradiation and determined by HPLC-DAD. The share of fungal mycelium in the total biomass was determined by extraction and quantitation of ergosterol. Additionally, water and oil binding capacity (WBC and OBC) were evaluated. Results A screening of basidiomycetes grown on agro-industrial side streams indicated a fast growth of Pleurotus sapidus on apple pomace. After 4 days of cultivation, the biomass obtained from this mushroom-substrate combination contained 21% true protein in dry matter. In addition to proteins, the amounts of lipids (4%), ash (2%) and carbohydrates (74%) were quantitated. The dominating fatty and amino acids of Pleurotus sapidus grown on apple pomace were linoleic acid and glutamic acid/glutamine, respectively. Concentrations of up to 115 µg (g dry matter) −1 vitamin D 2 were formed from ergosterol by UV-B irradiation. Ergosterol was used as a biomarker to monitor the amount of fungal content. Conclusion The nutritional value of agro-industrial side streams such as apple pomace can be upcycled by biotransformation with basidiomycetes.

Characterization of the Nutritional Composition of a Biotechnologically Produced Oyster Mushroom and its Physiological Effects in Obese Zucker Rats

“…[ 43 ] The PSC chitin content (5.9%) was also similar to that reported for the mycelia of P. sapidus grown on apple pomace, but ≈5% lower to that reported by Cheung. [ 16,44 ] Mushrooms were recently discovered to be the primary source of ergothioneine which is known for its antioxidant properties. [ 45,46 ] Ergothioneine content of PSC was in range with the concentrations reported for other mushrooms, but lower than those reported for fruiting bodies of the Pleurotus species.…”

“…PSC, as mentioned by Ahlborn et al., [ 16 ] was obtained from the culture collection present at the Institute of Food Chemistry and Food Biotechnology, Justus Liebig University, Giessen, Germany.…”

“…Determination of the crude protein, ash, fat, fatty acid profile, and amino acids in PSC were performed as described by Ahlborn et al. [ 16 ] The amount of carbohydrates was calculated as difference to 100%. For quantitation of glucans, the enzyme assay kit—mushroom and yeast beta‐glucan from Megazyme Inc. (Ireland) was utilized according to the manufacturer's protocol.…”

“…Chitin quantitation employed a colorimetric assay with 3‐methyl‐2‐benzothiazolinone hydrazone hydrochloride at 650 nm, with modifications. [ 16,18 ] Ergothioneine, a sulphur containing amino acid, was quantified in PSC, as described previously, [ 19 ] with modifications. Detailed methods have been provided in Section S2, Supporting Information.…”

Enzymatic Hydrolysis and Fermentation of Apple Pomace

“…Gegenwärtig wird das Verwertungspotenzial bei Weitem nicht ausgeschöpft. Stattdessen wird der Trester der Futtermittelproduktion oder Biogasanlagen zugeführt [2]. Apfeltrester ist eine inhomogene Mischung aus Schalen und Fruchtfleisch (95 %), Kernen (2-4 %) sowie Stielen (1 %) [3] und besteht somit zu über der Hälfte aus Kohlenhydraten, u. a. Cellulose, Hemicellulose, Pektin, Stärke und Saccharose.…”