Effect of Ultrasound on Alkali Extraction Protein from Rice Dreg Flour

In this study, Counter-current ultrasound-assisted alkali was employed to extract rice dreg protein (RDP) from rice dreg flour (RDF). The results indicated that extraction yield of RDP reached a maximum value at 0.08 mol/L alkali concentrate. It was only 43.20% in absence of ultrasound, whereas it reached up to 88.44% under ultrasonic condition. Amino acid composition, scanning electron microscopy, atomic force microscopy and fourier transform infrared spectra were used to determine amino acid composition, morphology, aggregates and microstructure of RDP. Ultrasound treatment could result in improving of hydrophobic amino acids content and changing of RDF and RDP microstructure, showing enhancement in the porosity of RDF particle, variation of RDP particle size. Thus, the acceleration of protein extraction was related to the changes of RDF and RDP microstructure caused by ultrasound. Counter-current ultrasound-assisted alkali extraction, as a modified method, was proved to be helpful in industrial manufacture of RDP from RDF. Practical Applications Low-frequency high-intensity ultrasound has been used in many aspects in laboratory, such as extraction of components, pretreatment. Counter-current ultrasound-assisted extraction was proved to be helpful in industrial manufacture of protein because it can dramatically improve extraction rate of rice dreg protein, and Counter-current ultrasound method can achieve continuous production of industrialization.