The global demand for new protein sources has increased, and the quality of lupine protein has been affected due to its anti-nutritional and anti-technical factors. Optimization of extraction process is crucial to obtain high quality lupine protein isolate, and high power ultrasonic pretreatment may be an effective strategy. This study aimed to evaluate the effects of high power ultrasonic pretreatment on lupine powder and protein isolate.
Use yellow lupine seeds, grind them into powder and set aside. Lupine powder was treated with conventional stirring and high power ultrasonic pretreatment, and water or ethanol-water was used as solvent at different time and temperature. After pretreatment, lupine protein concentrate and isolate were extracted respectively.
Solvent significantly affects the elastic properties of ultrasonic field, adding lupine powder will reduce the sound pressure, temperature increase will also reduce the sound pressure.
High power ultrasound and long pretreatment time can improve the extraction yield and protein yield of lupine protein concentrate, but have negative effects on the extraction yield of LPI. Pretreatment can increase the total protein yield, and the protein yield is the highest at 30°C water solvent ultrasonic treatment.
High power ultrasonic pretreatment can improve the fat absorption index and emulsification performance of LPI, and significantly affect the water and fat absorption capacity, foaming and emulsification performance of lupine protein concentrate.
Flour pretreatment could increase the protein extraction rate of lupine seeds and reduce the content of undesirable compounds. High power ultrasonic pretreatment has the best effect under the condition of 30°C and water solvent, which can effectively reduce the content of anti-nutrient factor and anti-technical factor, improve protein yield, maintain or enhance the technical functional properties of lupine protein concentrate and LPI, and provide a promising method for large-scale application of lupine protein in food industry.
