Abstract: In the alkali extraction and acid precipitation process of protein from hazelnut,effects of concentration and temperature on the functional properties of the protein were investigated,and its isoelectric point was determined. The optimal preparation conditions of the protein are as follows:solid-liquid ratio 1:6,40 ℃ alkali extraction at pH 8.0 for 0.5 h and acid precipitation at pH 4.5. Its foamability is the highest at the concentration of 4%,with the highest foam stability and emulsibility at the concentration of 2%. The emulsion stability is hardly affected by standing temperature. The oil adsorption ability is 3.72 ml/g. The protein dispersibility index(PDI) is the highest at 50 ℃,while the PDI value decreases above 50 ℃,keeping stable above 70 ℃. The water holding capacity attains the highest on the conditions of 1% concentration,60 ℃ and 1.5 hours. Its isoelectric point is measured to be 4.52.

Key words: hazelnut protein, extraction condition, functional properties, isoelectric point