Ultrasound

Isoelectric focusing

Yield (engineering)

Metallurgy

Materials science

Chromatography

Ultrafiltration (renal)

Solubility

Protein purification

Precipitation

Biochemistry

Solvent

Acoustics

Food science

Physics

Extraction (chemistry)

Organic chemistry

Enzyme

Isoelectric point

Chemistry

Meteorology

Food Research International

A new Ultrasound-Ultrafiltration-Assisted Alkaline Isoelectric Precipitation (UUAAIP) technique was employed for producing alfalfa protein isolate from alfalfa leaves. A five-factor-three-level Box-Behnken Design (BBD) was used to optimize the UUAAIP process for maximizing both extraction yield and protein content simultaneously. The optimum conditions were as follows: solvent/solid material ratio of 43.3 mL/g, pH of 10.1, extraction temperature of 42.5 °C, extraction time of 102 min, and flow rate of 9.7 L/h. Under these conditions, the maximum predicted extraction yield and protein content were 14.5 g/100 g and 91.1 g/100 g, respectively. UUAAIP technique improved the average molecular weight and color of the isolate. Moreover, it was efficient in removing the saponins and phenolic compounds as anti-nutritional factors compared to heat-coagulation extraction (HCE) and alkaline isoelectric precipitation extraction (AIPE). The protein isolate extracted by UUAAIP had greater solubility, water-holding and oil-binding capacities but lower emulsifying and foaming properties than those extracted by HCE and AIPE.

Application of Ultrasound-Ultrafiltration-Assisted alkaline isoelectric precipitation (UUAAIP) technique for producing alfalfa protein isolate for human consumption: Optimization, comparison, physicochemical, and functional properties