Can agronomic practices and cold-pressing extraction parameters affect phenols and polyphenols content in hempseed oils?

Hemp seed oil is an extraordinary dietary source of polyunsaturated fatty acids (PUFAs), to huge health benefits are related. PUFAs abundance could indeed contribute the oil turning rancid and deteriorating through oxidation. Thus, antioxidant compounds, characteristic of hemp seed matrix, should be more favorably extract to hopefully safeguard the oil stability. Moreover, antioxidants ability to counteract the onset of oxidative stress-related diseases could be employed to further enhance hemp seed oil functional value. In this context, phenols and polyphenols, which are poorly explored in hempseed oil so far, are thoroughly investigated by untargeted UHPLC-HRMS and MS/MS techniques in seed oils from Cannabis saliva L. cv USO31. Data recorded highlighted that hemp seed oil could contain, as minor constituents, saccharides, phenol compounds (some of them never described before - e.g. tyrosol hexoside, caffeoyl tartaric acid isomers), as well as flavonoids, of which glycosides of flavonols quercetin, kaempferol and isorhamnetin were the most representative. Glucuronide derivatives were also present. Multivariate principal-component analysis (PCA) highlighted that agronomic practices (e.g. plant density/m(2), use of fertilizers) and cold-pressing extraction parameters (e.g. temperature, nozzle size) massively affected the relative content of each compounds' class. Hemp seeds from soils, which did not undergo pre-seeding fertilization, and with 60 plant/m(2)crop density, ensured the highest production of phenols and polyphenols, whereas their abundance could be compromised when the plant density was halved.