EMULSIFYING CAPACITY OF HYDROLYZED POTATO PROTEIN

Enzymatic modification is a tool used in vegetal proteins to improve their functional properties. In this context, the aim of this work was to modify commercial potato protein by enzymatic hydrolysis and evaluate intact protein and hydrolysates. Potato protein was hydrolyzed by the protease Protamex to obtain hydrolysates with different degree of hydrolysis DH (1%, 2%, 4%, 6% and 10%) using pH-stat method. The functional properties of all hydrolysates were evaluated regarding to ζ-potential, determined by Zetasizer Nano; emulsion capacity (EC), by measuring the conductivity point when an oil-in-water emulsion changed to a water-in-oil emulsion; emulsion droplet size distribution and mean diameter by laser light diffraction instrument; and emulsion stability, evaluated by optical scanning instrument. No statistical difference in ζ-potential values were observed between the samples (-34mV to -38mV), except for DH6% (-25,8mV). The greater electrostatic repulsion between the droplets, higher is the stability. The sample DH2% presented highest value for CE (428g/g), and a statistical difference was observed between DH2%, DH10% (365g/g), and intact protein (P) (348g/g). Peptides with limited extend of hydrolysis are able to diffuse more rapidly to oil/water interface compared to intact proteins, improving the emulsifying capacity of the protein. Furthermore, a higher DH tends to cause reduction in the protein conformation that the resulting peptides are not able to form a strong matrix in the emulsion formation. A statistical difference in droplet size distribution was observed between DH2% (2.19) and P (1.65), whereas mean droplet diameter did not (8.34m and 10.06m, respectively). The sample DH2% also presented higher emulsion stability than the intact protein. Peptides showed to be able to improve EC and stability compared to the intact protein, especially hydrolysates with a low DH. Thereby, this study suggests that a modification in protein functional properties through limited enzymatic process is an attractive approach.