Onion juice waste for production of Pleurotus sajor-caju and pectinases

This work evaluated the production of fruit bodies and pectinases by Pleurotus sajor-caju, using onion waste as the substrate in solid state fermentation (SSF). The physicochemical characterization of the dehydrated onion waste was carried out. The production of fruit bodies was performed using onion waste in natura (IN) and the dried onion waste rehydrated by water immersion (WI). The pectinase present in the spent substrate was measured and characterized. The physicochemical analyzes showed that onion waste is a suitable substrate for SSF. The yield and the biological efficiency were 45.73 and 4.66%, respectively, when WI was used. There was no production of fruit bodies in IN. Pectinase activity in the spent substrate was 4.82 U mL(-1). The crude enzyme showed an optimum pH of 3.0 and 6.0 and optimum temperature at 80 C (7.62 +/- 0.32 U mL(-1)). The Michaelis-Menten constant (Km = 243.83 mM) and maximum reaction rate (V-max = 6.99 mM min(-1)) suggested a low affinity of the enzyme for the substrate. The results confirmed that is possible to add value to a residue of the food industry by producing P. sajor-caju fruiting bodies and a thermostable pectinase. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.