3.3. Surface hydrophobicity (So) and Salt-soluble proteins (SSP)
Changes in surface hydrophobicity (So) during repeated F/T were
possibly caused by a conformational shift in protein structure due to
the FA-induced formation of methylene bridges between protein
functional groups followed by exposure of a hydrophobic group of
aliphatic and aromatic amino acids. Overall, WF and HF showed
similar patterns in So as F/T repeated (Fig. 3a). So decreased at 3-F/T
and increased at 6-F/T, respectively (p < 0.05) before subsequent
decrease at 12-F/T (p < 0.05). Decreases in So at 3-F/T likely indicate
hydrophobic interactions, which stabilize the native protein structure.
At this point, the hydrophobic interaction possibly disrupted hydrogen
bonds of free water on the surface of hydrophobic protein sites (Santos-
Yap, 1996). The significant increase (p < 0.05) in So observed at 6-F/T
was possibly caused by the unfolding of hydrophobic groups of proteins
due to protein denaturation induced by FA and the So subsequently
dropped at 12-F/T as unfolded proteins aggregated. Protein's conformational
changes, as F/T repeated, can be confirmed by Fourier