Mild oxidative degradation of spent auricularia auricular substrate and molecular composition of carboxylic acids in the resulting soluble portion

Abstract

Spent auricularia auricular substrate (SAAS) was oxidatively degraded with aqueous hydrogen peroxide (AHPO)/acetic anhydride (AAH) to produce carboxylic acids (CAs) under mild conditions. The results show that up to 53.6% of the organic matter in SAAS was converted to the soluble species (SSs). In total 122 CAs were detected in the SSs by the analysis with a gas chromatograph/mass spectrometer, which can be classified into 29 group components, mainly being aliphatic acids and along with small amount of aromatic acids. Among the aliphatic acids, normal alkanedioic acids are the most abundant. The detected aromatic acids include benzoic acids, phthalic acids, trimellitic acids, pyromellitic acids, and their derivatives. The synergistic oxidation and the released OH, CH 3 COO , and HOO induced by AHPO/AAH play crucial roles in oxidatively degrading SAAS. • SAAS can be degraded to produce CAs, which consists of aliphatic acids and aromatic acids. • Aliphatic acids represent the predominant species, and NADAs are the most abundant. • AHPO/AAH ratio and temperature have impact on the composition and yield of CAs. • OH, CH 3 COO , and HOO play crucial roles in the SAAS oxidative degradation.