Fertilisation with ash from biomass combustion has a positive effect on the quality of nutrients in agrifood raw materials, improving their chemical composition and bioavailability. In the experiments carried out, the protein content and the profile of free amino acids in barley flour were examined from cultivation fertilised with biomass ash at various doses. Barley flour from Haplic Luvisol soil was characterised by a significantly higher (by 13.8% on average) total protein content compared to flour obtained from grains from Gleyic Chernozem soil. The highest protein content but a low content of free amino acids were found in the grains of plants fertilised with the mineral NPK (D1). An increase in the total pool of free amino acids in flour was observed, especially in the case of Haplic Luvisol soil. On average, after fertilising, significantly more ASP, ASN, GLU, GLY, ALA, and CYS were obtained in variant D4 (1.5 t·ha-1), and there were also significantly more TAU and GABA than in the control, up by 30.2% and 23%, respectively. A beneficial effect of fertilisation on the essential amino acid content in barley flour was found, but only up to the dose of D4, when it was significantly higher than in the control and under mineral fertilising (D1), up by 23.7% and 9.2%, respectively. High ash doses reduced the content of free amino acids in the tested barley flour. This study confirmed that using an alternative method of fertilising with plant biomass ash has a beneficial effect on protein quality and nutritional value.
Keywords: barley; biomass ash; fertilisation; free amino acid.