using a 2 mol/L NaOH solution (pH 8.0) followed by the titration
with 2 mol/L HCl to pH 4.5 to precipitate pea protein at its isoelectric
point. The pellet was washed twice with distilled water
followed by centrifugation at 6000 g for 10 min at 4 C. Thereafter,
the protein pellet was resuspended in distilled water and neutralized
to pH 7.0 with 2 mol/L NaOH. The PPI suspensions were freezedried
and stored at 4 C before use. Because all three batches were
found to have strong radical-scavenging and reducing activities and
the assay results were extremely consistent (described later), they
were pooled then applied to the testing for cured meat color protection
as well as the inhibition of lipid and protein oxidation which
were tested in three independent trials (n ¼ 3).