LC/MS Q-TOF analysis of Pleurotus ostreatus: lipid classes and molecular species

In recent years, wild and cultivated edible mushrooms have attracted attention as a valuable meat substitute, in particular for vegetarian and vegan dietetic approach. Mushrooms show favourable chemical composition with high amounts of functional proteins and fibre, and low total fat level, together with a low glycaemic index, making them well suited for low calorie diets. To date, numerous edible mushroom species, growing in various suitable ecological conditions, are known among which Pleurotus spp. (oyster). In particular, P. ostreatus is gaining increasing dietetic importance, being particularly rich in bioactive compounds, among which antioxidants and essential fatty acids which emphasizes its potential application in the promotion of cardiovascular health. Due to the limited availability of P. ostreatus lipid data, the aim of this study was to deepen the knowledge regarding the lipid fraction of P. ostreatus samples by using an untargeted LC/MS Q-TOF analysis. In the past, the lipid analysis relied on the use of thin layer chromatography or gas chromatography after the derivation of polar functionalities, but nowadays the use of (ultra)high-performance liquid chromatography, coupled with suitable mass-detectors, is the most performing technique. Numerous lipid classes, as well as interesting molecular species, have been detected and deeply characterized. Besides common fatty acids, among which polyunsaturated fatty acids, some unusual characteristics were highlighted, such as odd and oxygenated chains, and ether in addition to ester bonds. The results of lipid class composition, subjected to multivariate statistical analysis, were able to differentiate P. ostreatus samples on the base of grown substrate. Further studies on a larger sampling will be necessary in order to apply lipidomics data to discriminate also mushroom species and geographical origin.