New insights in hemp seed phenols and polyphenols through uhplc-esi-qtof-ms/ms analysis

Hemp seeds are an extraordinary nutritional source and hemp seed oil (HSO) is especially rich in essential polyunsaturated fatty acids (PUFAs), vitamin E, and sterols. Indeed, whilst the high PUFAs abundance defines the huge health benefits of HSO intake, it makes HSO turning rancid and deteriorating through oxidation. To prevent these side effects, antioxidant compounds, typical of hemp seeds, should be more favorably extracted. In particular, polyphenols are aimed at increasing HSO shelf-life and at improving its organoleptic features being able to deactivate and/or suppress harmful free radical species. Plant polyphenols, which are distinguishable on the basis of the number of phenol rings and the structural elements that bind these rings to one another, enjoy an ever-increasing recognition due to their antioxidant activity, which is able to efficaciously counter the ill-effects of oxygen metabolism in cells. Thus, maximizing polyphenol concentration in HSO is the main objective to be pursued, and extractive conditions have to be optimized as high temperatures, commonly generated during cold-pressing extraction, could negatively affect both polyphenols concentration and oil quality. In order to improve these extractive conditions, both cold pressing extraction parameters, such as nozzle size and temperature, and the influence of different agronomic practices (e.g. plant density/m2, fertilizers’ use) were examined. Phenol and polyphenol composition was investigated by using UHPLC-HRMS and MS/MS techniques. Data acquired highlighted that phenols and polyphenols were abundant when seeds were planted at a 60 plant/m2crop density. An extraction temperature of 40°C, achieved with a nozzle diameter of 8mm, seemed to increase the flavonoids’ content.