After 24 hours of reaction, the solid membrane was removed and the concentration of leached enzyme was evaluated via the Bradford method (ESI). The leached TA fraction (%) is defined as the ratio between the mass of leached TA after one catalytic test and the initial immobilized TA loading (L). 50 mM 3,3-diphenylpropionic acid (3-DPPA) was added to the reaction medium in order to crystallize with the remaining BMBA (in the form of a BMBA:DPPA salt). After 20 hours of crystallization, crystals were filtered, washed twice with 5 mL distilled water, then once with 5 mL tert-butyl methyl ether (MTBE) to remove residual BAP, and then dried at room temperature overnight. Semi-quantification of BMBA enantiomers was then determined using Chiral High-Performance Liquid Chromatography (Chiral-HPLC), by dissolving the obtained crystals in the mobile phase (95% isohexane/5% 2propanol/0.1% diethylamine) (see ESI).