Abstract:

The effects of pH, NaCl concentration and temperature on functional properties (solubility, water-holding
capacity (WHC), emulsifying activity (EA), emulsifying stability (ES), foaming capacity (FC) and foam stability (FS)) of
protein extracted by alkali from potato starch wastewater and precipitated by acid were investigated. The results showed
that functional properties of potato protein were affected by pH, NaCl concentration and temperature to different extents.
Solubility, WHC, EA, ES and FC were the lowest at its isoelectric point (pH 4.0), while FS exhibited the best properties.
Solubility, WHC, EA and ES were improved by increasing NaCl concentration (0–0.2 mol/L), but inhibited by higher NaCl
concentration (> 0.2 mol/L). On the other hand, FC and FS reached their maximum values at NaCl concentration of 0.4 mol/L.
As temperature increased from 4 to 80 ℃, all functional properties increased at first and decreased later. Potato protein
exhibited the highest solubility, WHC, ES, FC and FS at 40 ℃ and best EA at 60 ℃.

Key words: potato starch wastewater, protein, solubility, water-holding capacity, emulsifying properties, foaming properties