Impact of the use of pressurized liquids on the extraction and functionality of proteins and bioactives from brewer's spent grain.

A green methodology based on pressurized liquids (PLE) to extract proteins and obtain highly active extracts from brewer's spent grain (BSG) is proposed. Box-Behnken experimental design was employed to study the effect of extraction parameters on the protein content (PC), the total phenolic content (TPC), and the antioxidant activity of extracts. Results were compared with those obtained by conventional alkaline extraction assisted with ultrasounds (UAE). The selection of PLE conditions enabled to tailor the PC and TPC of extracts. PLE extracted 36 % more proteins than UAE. PLE extracts showed higher antioxidant, cholesterol esterase inhibition, and ACE inhibitory activities than UAE extract. HPLC-MS/MS enabled to observe that the extraction technique and experimental conditions significantly affected to the kind and amount of extracted proteins, and released peptides, and phenolic compounds. A higher ratio of hydrophobic peptides was observed in PLE extracts, which justified their higher bioactivity.