Characterization of the sterol fraction of barley grains obtained with two different organic agricultural systems

Phytosterols are one of the most representative liposoluble minor components of plants and cereals and are useful for recognizing their actual source of origin. The aim of this study was to characterize the sterol fraction of barley grains produced by using two different organic fertilizers (distillery vinasse as top-dress application and a mixed vegetable-animal compost, soil-incorporated prior to seeding). Barley was grown in two different locations (Altedo and Imola) in 2003 and in only one site (Altedo) in 2005; the trial was laid out as a randomized block with four replicates. The grains were collected, dried at 40°C and milled. Lipids were extracted, subjected to cold saponification, purified by thin-layer chromatography, silylated and analyzed by gas chromatography (GC). Sterols were identified and quantified by GC and GC-mass spectrometry. The main phytosterol found was beta-sitosterol (52.3% of total sterols), followed by campesterol (20.0%), 5-avenasterol (9.5%), stigmasterol (3.7%), 7-avenasterol (3.7%) and 7-stigmastenol (2.2%). Ten minor phytosterols, present at concentration levels below 2%, constituted 8.6% of total sterols. For the 2003 harvest, no significant differences were observed in the sterol content of barley grains grown in the different locations; however, the barley grains fertilized with vinasse exhibited a significantly higher sterol content with respect to those obtained with compost incorporation. Regarding the 2005 harvest, no significant differences were found in the sterol content of the barley grains obtained with the two different organic fertilizers.