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 9 the amino acid industry.