Cross Flow Microfiltration System in Separating Fermented Nixtamal Corn for Preparation of Natural Folic Acid

A purification process of biomass of nixtamal yellow corn fermented by Rhizopus oligosporus strain C1 (FNC-A) and Rhizopus sp (FNC-B) was performed using a microfiltration (MF) membrane with pore size 0.15 µm installed in a crossflow microfiltration (CFMF) system to obtain retentate and permeate fractions as natural folic acid preparations. CFMF process was conducted at room temperature with a pump motor frequency (PMF) of 10 Hz (flow rate of 3.5 L/min) and a transmembrane pressure (TMP) of 4 bar for 0, 15, 30, 45, 60, 75, and 90 minutes. Based on optimum folic acid, the results showed that the best treatments of FNC-B and FNC-B were achieved at 90 min, resulting in a folic acid increase in retentate of FNC-A and FNC- B of 72.61 and 95.26%, reducing sugar of 20.41 and 170.93% (1.7-folds), total sugars of 155.51% (1.55-folds) and 426.76% (4.27-folds), and dissolved protein of 55.33 and 39.20%, and decrease in total solids of 88.91 and 91.64%, respectively, compared to initial biomass of FNC-A and FNC-B. The MFCF system effectively separated folic acid in retentates of FNC-A (33.77%) and FNC-B (95.27%) at the optimal condition. Folic acid monomers predominated the characteristics of FNC-A and FNC-B in optimum conditions with molecular weights of 442.10 and 442.18 Dalton, the average particle size of 38.31 μm and 37.97 μm, and distribution of particles at 10, 50, and 90% from the particle size 10.31, 26.32 and 81.55 μm, and 10.37, 28.04 and 76.09 μm, respectively.