Process Integration of Separation of Amino Acids by a Temperature-Induced Aqueous Two-Phase System

Random copolymers of ethylene oxide and propylene oxide (EOPO) and (hydroxypropyl)starch (PES) have been used in aqueous two-phase partitioning of amino acids. The partitioning behaviors of l-Ile and l-Val were investigated in EOPO/PES aqueous two-phase systems (ATPSs). The effects of the addition of salt and pH on the partitioning were studied. Fundamental data were employed for further scale-up to process 1000 mL of fermentation broth. An integrated bioseparation process was designed on the basis of the partitioning behavior of amino acids in the primary ATPSs and in the temperature-induced phase systems. l-Ile crystals were finally obtained through (1) selective partition in the EOPO/PES system, (2) recovery from the water phase during the temperature-induced phase separation of the EOPO phase, and (3) crystallization from the water phase by isoelectric precipitation. The mass of l-Ile crystals was 13.76 g with a purity of 97.17%. The overall recovery was 74.28%. Aqueous two-phase extraction combined with temperature-induced phase separation appears to be a promising alternative in the amino acid industry.