Investigation on Rapid Measurement of Water-soluble Soybean Protein through Spectrophotometry

A purple-red complex could be formed rapidly between azocarmine G and water-soluble soybean protein in acidic medium.The absorbance of this complex had a maximum absorption wavelength at 580 nm and exhibited a bathochromic shift of 50 nm compared with the maximum absorption wavelength of azocarmine G.Its absorbance with the concentration of soluble proteins at least in 3~34 μg·mL-1 was linearly.A method on rapid measurement of water-soluble soybean protein was established based on above-mentioned.Simultaneously we optimized the extraction procedure of water-soluble soybean protein.The results obtained by this method was rapid,stable.And the results were same with that obtained by Kjeldahl's method.