Maltose

To conduct high-performance liquid chromatography (HPLC) analysis, a 5 mL sample was centrifuged at 10,000 × g for 10 min and the supernatant was filtered using 0.2 μm filters (Whatman, United Kingdom). Organic acids (lactic acid and acetic acid) were measured using HPLC 1260 Infinity (Agilent Technologies, United States) with Aminex HPX-87H column (300 × 7.8 mm; BioRad, CA, United States) under the operation setting: 0.008N H₂SO₄ in water as mobile phase, 20 μL of sample injection volume and 0.6 mL/min of flow rate. Sugars (glucose, maltose, maltotriose, maltotetrose, maltopentaose, and maltohexaose) were measured using HPLC Acme 9000 (Younglin, South Korea) with VN-50 4D column (150 × 4.6 mm; Shodex, Japan) under the operation setting: 67% acetonitrile (v/v) as mobile phase, 10 μL of sample injection volume and 0.3 mL/min of flow rate. Organic acids and sugars were detected using UV (215 nm) and RI detectors, respectively. Lactic acid, acetic acid (Wako, Japan), glucose, maltose (Junsei, Japan), maltotriose, maltotetrose, maltopentaose, and maltohexaose (TCI, Japan) were used as standards.