Tofu wastewater recovery for mannoprotein production from yeast and mold cell walls

This study used tofu wastewater as medium to produce mannoprotein from Candida tropicalis (MCT), Pichia norvegensis (MPN), Aspergillus awamori (MAA), and Rhizopus oryzae (MRO). This study aimed to determine the optimum growth of yeast and mold in tofu wastewater as a medium for mannoprotein production. The purity was determined using FTIR and solid-state NMR spectroscopy. The structural differences were determined using scanning electron microscopy (SEM), and the antioxidant activity was measured using DPPH radical scavenging activity. The highest yield of extract was obtained upon the use of MPN (28.09 ± 6.4%, w/w), followed by MCT (18.73 ± 5.5%, w/w), MRO (2.75 ± 1.7%, w/w), and MAA (2.54 ± 1.7%, w/w). Moreover, FTIR spectroscopy confirmed that MCT, MPN, MAA, and MRO were typical mannoproteins with absorption band at 824, 824, 818, and 812 cm−1, respectively. While the1H NMR spectra revealed the presence of protons at 5.11–5.46 ppm which confirmed the presence of α-(1,2)-mannoprotein for MCT, α-(1,6)(1,2)-mannoprotein for MPN, and α-(1,6)-mannoprotein for MAA, and MRO. Mold-based mannoprotein has a smaller particle size than yeast-based mannoprotein, furthermore, at 4000 ppm, MCT had the greatest DPPH-free radical inhibition value of 49.89%, followed by MRO (44.34%), MAA (40.81%), and MPN (28.54%).