The phosphorus–potassium solution that was used
was a byproduct, that came from processing of a protein
concentrate. This process consisted initially in grinding
and defatting sunflower flour. Three samples in triplicate
were subjected to a protein extraction process with a
KOH 0.5 N solution at 40 C during one hour. Proteins
were subsequently precipitated with a pH 4.5 and 0.5 N
phosphoric acid solution; they were finally decanted, filtered
and centrifuged. Finally, the precipitate was
washed and dried, obtaining a powder-like protein concentrate
(Ordon˜ez et al., 2001). The scheme of the process
to obtain the experimental solution is shown in
Fig. 1 (Ordon˜ez et al., 2001).