Determination of phenolic compounds in residual brewing yeast using matrix solid-phase dispersion extraction assisted...

A simple and efficient low-cost matrix solid-phase dispersion (MSPD) extraction based on TiO₂ nanoparticles (NPs) and diatomaceous earth has been developed for the recovery of phenolic compounds from residual brewing yeast. Experimental conditions for MSPD extraction were optimized by an experimental design approach. A screening factorial design plus replicates at the center point, followed by surface response analysis were used. The simultaneous identification and quantification of eleven main natural polyphenols: caffeic, chlorogenic, p-coumaric, 3,4-dihydroxibenzoic, trans-ferulic and gallic acids, kaempferol, myricetin, naringin, quercetin and rutin, was possible by combining MSPD and capillary liquid chromatography couple to a diode array detection system (cLC-DAD) and liquid chromatography couple to a triple quadrupole analyzer (LC-MS/MS). Moreover, residual brewing yeast extracts were evaluated in terms of DPPH (1,1-diphenyl-2 picrylhydrazyl) free radical scavenging activity. Polyphenol-nanoparticle interaction was studied by UV-vis spectroscopy and electron transmission microscopy (TEM), pointing out a stable interplay that assists phenolic isolation. The extracted polyphenol quantities were within the 3.2-1,500 μg g^-1 range, and the high antioxidant activity estimated suggested that developed MSPD is a successful, simple, efficient and rapid method for the extraction and recovery of bioactive phenolic compounds, which promotes the reuse and re-evaluation of brewing yeast agri-food by-products.