Small-scale conversion was confirmed in a 1 L scale reactor, aiming at more than a 2 M concentration of GABA conversion, as shown in Figure 3B. As a result, 2.17 M GABA was obtained upon termination, while the conductivity was 4.78 mS/cm due to salt formation, and 18 mM GA remained. To our knowledge, the highest GABA concentration was achieved within one hour of processing time