Doubanjiang, a Chinese traditional fermented red pepper paste, is eaten worldwide for its unique flavor. The objective of this study was to evaluate the aroma quality of doubanjiang using solvent-assisted flavor evaporation (SAFE) and headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-olfactometry (GC-O) and aroma extract dilution analysis (AEDA). A total of 165 volatile compounds, belonging to 13 chemical classes, were identified. Esters and hydrocarbons were the predominant groups. Thirteen aroma-active compounds were detected by AEDA of SAFE and HS-SPME, and their odor activity values (OAVs) were calculated by dividing their concentration by their odor threshold in water. Among them, ethyl isovalerate, β-damascenone, 3-isobutyl-2-methoxypyrazine (IBMP), and sotolone had the highest OAVs (>1000). In addition, sotolone, methional, β-damascenone, 3-isobutyl-2-methoxypyrazine, ethyl isovalerate, phenylethyl alcohol and linalool had high flavor dilution (FD) factors. Sotolone, β-damascenone and 3-isobutyl-2-methoxypyrazine were identified for the first time in doubanjiang and played significant roles in its aroma quality.

In this study, Phellinus linteus polysaccharides (PLPS) and proteins were simultaneously separated from P. linteus mycelia by using an aqueous two-phase system (ATPS) based on choline chloride ([Chol]Cl)/K₂HPO₄, and the physicochemical and antioxidant properties of PLPS after ATPS extraction were evaluated. Results demonstrated that the maximal extraction efficiencies of 68.53% ± 0.29% PLPS and 82.37% ± 0.41% proteins were obtained when the cholinium-based ATPS contained 68.9% K₂HPO₄, 20% [Chol]Cl, 10.0 mg mL⁻¹ crude water extract (1.0 mL), and distilled water (4.0 mL) at shaking time and temperature of 30 min and 21.2 °C, respectively. Compared with C-PLPS obtained using traditional ethanol precipitation and isolation protocols, PLPS had higher carbohydrate content (63.58% ± 1.12%), lower molecular weight (15.2 kDa, 80%), different monosaccharide compositions, and showed similar preliminary structural characterizations. Moreover, PLPS exhibited more evident scavenging effects on free radicals and in vitro antioxidant activities than C-PLPS. Therefore, the method of [Chol]Cl/K₂HPO₄ ATPS can be developed as an effective strategy for the separation/purification of highly bioactive polysaccharides.