Technology optimization of Medicago sativa leaf protein separation with foam fractionation

Abstract: In order to purify Medicago sativa leaf protein effectively, foam fractionation which could increase both enrichment ratio and recovery of Medicago sativa leaf protein, was developed based on the research of the influences of initial pH value, the air flow rate, the loading liquid volume and the ratio of material to solvent. Then the best single factor was defined which was the loading liquid volume of 550 mL, pH value of 6.5, the ratio of material to solvent of 87.5 mg/L, the air flow rate of 250 mL/min. Based on the single factor experiment, Box-Behnken design was adopted to investigate the influence of four factors: pH value, the loading liquid volume, concentration and the air flow rate on recovery and enrichment ratio of leaf protein from Medicago sativa. Response surface and contour plots were finally graphed with the recovery and enrichment ratio as the response value. The foam fractionation of leaf protein from Medicago sativa was optimized by response surface methodology. The model P-value were both smaller than 0.0001 and the model were goodness-of-fit and the adequacy of the regression model. The optimum conditions for the foam fractionation of leaf protein from Medicago sativa were found to pH value of 6.92 , the ratio of material to solvent of 87.5 mg/L, the loading liquid volume of 600 mL, the air flow rate of 200 mL/min. Under the conditions, the recovery of Medicago sativa leaf protein was 92.2% and the enrichment ratio was 8.03. Considering actual process, The optimization processes were pH value of 7.0 , the ratio of material to solvent of 87.5 mg/L, the loading liquid volume of 600 mL, the air flow rate of 200 mL/min. The recovery of Medicago sativa leaf protein was 90.2% and the enrichment ratio was 7.64. respectively. The experimental results showed that foam fractionation was an effective method to separate leaf protein from Medicago sativa.