Pleurotus ostreatus, or oyster mushroom, is the most widely consumed and studied species. Because of its high protein and amino acid content, it can be used as a meat substitute. Food quality and composition can be improved by utilizing various technologies, including emerging thermal and non-thermal techniques. The study aim was to determine the effect of various pretreatment technologies on the amino acid and biogenic amine content of fresh and fermented oyster mushrooms. An automatic amino acid analyzer was used to perform a chromatographic analysis on free amino acids and biogenic amines. Significant differences were found between fresh and fermented mushroom samples: the fresh samples showed an increased FAA value (+57%), while blanching and microwaving them stabilized the FAA content. In the other groups, a 9–17% reduction was observed. The total biogenic amine composition increased 11- and 15-fold in the fresh and UV-treated samples (1.89 and 5.05 mg/g, respectively). The blanched samples showed no major change while the other groups increased by two to five times. The results of our study provide an excellent basis for the development of oyster-mushroom-based food products, whether for use in meat products or novel vegan products.

Reducing meat and meat product consumption addresses both sustainability and environmental concerns. Oyster mushrooms ( Pleurotus ostreatus ) are promising meat substitutes, however, their effect on the chemical profile of reformulated meat products requires further investigation. The purpose of this study was to investigate how partial pork meat replacement (25% and 50%) with pretreated and fermented oyster mushrooms affected the amino acid and biogenic amine content of sausages. Prior to fermentation and sausage production, mushrooms were pretreated thermally (blanching, steaming, oven, microwave) and non‐thermally (HHP: high hydrostatic pressure, UV: ultraviolet light). Although the total amino acid content decreased with mushroom substitution, the total essential amino acid and total branched‐chain amino acid content remained relatively high, accounting for 45%–53% and 15%–20% of the total amino acids (AA), respectively. The total free amino acid content increased due to enhanced umami‐contributing glutamic acid (Glu), aspartic acid (Asp), and health‐promoting gamma‐aminobutyric acid. The total biogenic amine content increased in the reformulated sausage samples, but no histamine was detected. In conclusion, reformulated sausage with fermented oyster mushrooms resulted in nutritious hybrid sausages based on the amino acid and biogenic amine composition.