Metabolomic analysis of browning mechanisms of morels (Morchella sextelata) during storage

Browning is a major problem affecting the quality of the morel. This study aims to clarify the browning mechanisms of the morel in terms of metabolite changes during storage. Morels were stored at 20 °C and 4 °C, respectively, and browned gradually with the extension of the storage periods. The soluble quinone content was increased, while the total phenolic content was decreased in the later storage periods. Metabolomics analysis revealed that many metabolic profiles of substances in morel were altered with increased amino acids and fatty acids and decreased soluble sugars, organic acids and some phenolics with the browning process in storage. Especially, dopamine, a precursor of melanin produced from tyrosine oxidation, was up-accumulated after storage. However, quinone, the browning substance was increased after storage. Through the metabolomic results and correlation analysis, it could be suggested that tyrosine metabolism was a vital pathway leading to the browning of morels during storage. The membrane lipid and energy metabolism involved in the upstream of tyrosine metabolism pathway might also concern the browning of morels during storage.