ABSTRACT
Pulsed electric field (PEF) treatment was applied to inactivate the proteolytic activity of two commercial endoproteases and to stop the hydrolysis process on faba bean protein concentrates (PC). The enzymatic inactivation capabilities of PEF, as well as the solubility and water absorption capacity of protein hydrolysates stabilized by PEF, were compared to those obtained by two traditional methods: (a) thermal treatment at 92°C for 5 min, and (b) acid conditions lowering the pH to 4.
Faba bean protein hydrolysate suspensions containing 50 μg/mL of an enzyme mixture (Protamex™:Alcalase™, 1:1) were treated with PEF in a continuous system (coaxial treatment chamber) with 1–181 pulses of 2–4 μs and electric fields from 42 to 78 kV/cm. Processing temperature was kept below 32°C. No residual activity of the enzymes was detected after 31 pulses at 78 kV/cm, or at 24, 48, or 72 hours after storage at 4°C. A residual activity of 60% was measurable after the thermal and acidification treatments, therefore they were not as effective as PEF, in inactivating the proteases or stopping the hydrolysis of the PC. Furthermore, the protein solubility index (PSI) and the water absorption capacity (WAC) were higher in those solutions of protein hydrolysates treated with PEF, compared to thermal and acid treatments.
