Functional properties of flours and protein concentrates of 3 strains of the edible mushroom Pleurotus ostreatus

Angélica Cruz-Solorio, Ramón Villanueva-Arce, María E. Garín-Aguilar, Hermilo Leal-Lara, Gustavo Valencia-del Toro

Pleurotus ostreatus is an edible mushroom with significant nutritional properties and highly valuable protein concentrates can be obtained from its fruit bodies. Functional properties of flours and protein concentrates derived from 3 Pleurotus ostreatus strains (PCM, POS and hybrid PCM × POS) were evaluated in this investigation. Fruit bodies were produced on wheat straw substrate, flours were obtained from dried and grinded fruit bodies and protein concentrates were extracted from flours by alkaline solubilization. For all 3 strains, pale yellow flours were obtained and protein concentrates showed a grayish brown color. Flour bulk densities ranged from 0.52 to 0.64 g/mL, a higher value than those for protein concentrates, i.e. 0.30-0.35 g/mL. The highest water absorption capacities (WAC) were observed for flours (300-418.8%) while protein concentrates presented higher oil absorption capacity (OAC) (173.3-214.1%). Flours and protein concentrates presented a minimal gelation concentration of 2%. Protein concentrates showed a higher foam capacity formation (FC) at pH 8. Likewise, flours and protein concentrates presented higher foam stability (FS) at alkaline pH (8 and 10). Emulsion activity index (EAI) for flours ranged from 3.96 to 26.68 m2 g-1 whereas for protein concentrates ranged from 1.55 to 10.28 m2 g-1. These results indicate that flours and protein concentrates from P. ostreatus have remarkable functional properties, valuable in food industry where foaming and emulsifying properties are required.