Tofu Wastewater Recovery for β-glucan Production by Pichia norvegensis and Candida tropicalis

This study aims to determine the applicability of tofu wastewater as a medium for yeast growth and to determine the optimal growth time of yeast to produce β-glucans, as well as the yield and characteristics of β-glucans extract. Pichia norvegensis and Candida tropicalis cell walls were extracted for β-glucan. FTIR, solid-state NMR, and SEM were utilized to investigate purity, structural differences, and antioxidant activity. Candida tropicalis (BCT) yielded 3.20 % crude β-glucan, while Pichia norvegiensis NYI (BPN) yielded 2.10 %. FTIR showed β-glucan impurities in mannoprotein-chitosan combinations. BPN and BCT have β-glucan bands at 1075, 1041, and 894 cm⁻¹. The impurity of both samples was confirmed by NMR spectra, which showed that the broad signal of BPN and BCT chemical shift at 4.803–4.587 ppm and at 4.764–4.541 ppm, respectively, corresponded to l β-1,3-glucosidic and β-1,6-glucosidic linkage, with some unusual anomeric resonance at 5.094–5.024 ppm by SEM, BPN and BCT were porous, sheet-like, and fibrous. BPN had 20.07 % DPPH radical scavenging activity, while BCT had 36.01 %.