Evaluation of physicochemical properties, equivalent umami concentration and antioxidant activity of Coprinus comatus prepared by different drying methods

Abstract

Coprinus comatus contains a variety of bioactive and umami compounds and is regarded as “the rising star of fungi”. To maximally maintain its quality, the physicochemical and antioxidant properties of C. comatus were investigated and compared, after undergoing hot air drying (HAD), infrared drying (IRD), microwave drying (MD) and freeze drying (FD). Results showed that different drying methods have their respective advantages. FD sample showed the lowest color difference and highest rehydration ratio, as well as provided the highest retention of gallic acid (223.76 μg/g) and protocatechuic acid (336.67 μg/g), thereby demonstrating highest free radicals (DPPH· and ABTS·) scavenging activity. MD significantly retained polysaccharide (113.36 mg/g), coumaric acid (13.36 μg/g) and p-hydroxybenzoic acid (35.09 μg/g), and exhibited higher ferric reducing antioxidant power. IRD and HAD led to higher contents of monosodium glutamate-like free amino acids and flavor 5′-nucleotide. In addition, IRD sample had the highest equivalent umami concentration value (1145.73 g MSG/100 g). Comprehensively, FD was better to preserve the antioxidants, while IRD would be a potential method to produce dried C. comatus with high umami concentration.