The influence of combined extrusion and fermentation processes on the chemical and biosafety parameters of wheat bran

The aim of this study was to evaluate the influence of combining extrusion and fermentation processes on the chemical and biosafety of wheat processing by-products (WPBP). Extrusion experiments were performed by testing two different temperatures (115 and 130 °C) and three different speeds of extruder screw (16, 20, and 25 rpm). The lactic acid bacteria (LAB) L. casei and L. paracasei were used for WPBP fermentation. A high-performance liquid chromatograph coupled to a triple quadrupole mass spectrometer was used for mycotoxin analysis and a high-performance liquid chromatograph with an ultraviolet detector was used for biogenic amine (BA) determination in WPBP. A significant effect of the type of LAB on the acidity of fermented WPBP was found. Although lower pH was observed for non-extruded fermented WPBP samples, they contained higher concentrations of D(−)-lactic acid. In extruded and extruded/fermented WPBP, the total BA content was two times lower than that in controls. The lowest mycotoxin concentration was found in fermented WPBP extruded at 130 °C using a screw speed of 20 and 25 rpm. Finally, the combination of extrusion and fermentation can be confirmed as a promising innovative pre-treatment for WPBP, potentially capable of reducing the content of BAs and mycotoxins.