Proteins recovery from wet microalgae using liquid biphasic flotation (LBF)

In this work, the extraction of microalgal protein from wet Chlorella sorokiniana species using alcohol/salt liquid biphasic flotation (LBF) with the aid of ultrasonication for cell rupturing was proposed. The effect of varying crude feedstock concentration, flotation time, salt type, salt concentration, alcohol type, alcohol concentration, initial volumes of salt and alcohol were investigated. After the optimization process, the highest proportion of protein recovered in the top phase was achieved with 250 g/L ammonium sulphate, 60% (v/v) 2-propanol, 1.0 V_R,initial, 20 g/L crude biomass load, 4 mm³/min air flowrate and 10 min of flotation time. The recycling of phase components was introduced to minimize the use of alcohol and salt in the corresponding LBF. It was demonstrated that top phase (alcohol) recycling can achieve increasing performance for three consecutive recycling runs. Under optimized process conditions, the proportion of protein recovered in the top phase was 88.86% for the third recycle run.