# Enhancing the Content of Hesperidin and Nobiletin in Citrus Wines through Multi-Strain Fermentation
## 2 Materials and Methods
### Determination of Aroma Components  
The volatile aroma components of Nanfeng tangerine wine were analyzed using HS-SPME-GC-MS (Supelco, Bellefonte, PA, USA), based on previous research methods with some modifications [17]. A precise 5 mL sample of Nanfeng tangerine wine was taken into a 20 mL headspace extraction vial, to which 1.5 g of NaCl and 5 \(\upmu\)L of a 10 mg/mL cyclohexanone solution as an internal standard were added. Following a 20-min equilibration at 40 \({}^{\circ}\)C, a mature DVB/CAR/PDMS extraction fiber from Supelco in Bellefonte, PA, USA, was placed in the vial, with the fiber protruding 2 cm above the liquid sample, and absorbed at 40 \({}^{\circ}\)C for 52 min. The sample was gently vortexed at 750 rpm using a magnetic stirrer during the equilibration and adsorption phases. The extraction fiber was  
\begin{table}
\begin{tabular}{c c c c c c} \hline  & \multicolumn{2}{c}{**Amount of**} & & \multicolumn{1}{c}{**DPPH Free**} & **ABTS Free** \\  & **Ethanol (\%)** & **Residual Sugar** & **pH** & **Total Acid (g/L)** & **Radical** & **Radical** \\  & & **(g/L)** & & & & \\ \hline Juice & - & - & 4.13 \(\pm\) 0.02 b & 8.96 \(\pm\) 0.16 f & 65.04\% \(\pm\) 0.02 a & 61.28\% \(\pm\) 0.01 abc \\ Sc & 11.13 \(\pm\) 0.02 a & 1.56 \(\pm\) 0.13 ef & 4.14 \(\pm\) 0.01 b & 9.97 \(\pm\) 0.24 e & 64.12\% \(\pm\) 0.02 a & 60.05\% \(\pm\) 0.01 bc \\ Hg-10-Sc & 10.73 \(\pm\) 0.08 abc & 2.33 \(\pm\) 0.08 a & 3.96 \(\pm\) 0.00 h & 11.25 \(\pm\) 0.09 a & 61.47\% \(\pm\) 0.02 abc & 56.65\% \(\pm\) 0.02 e \\ (Ce.Hg)-10-Sc & 10.87 \(\pm\) 0.03 ab & 0.68 \(\pm\) 0.05 g & 4.03 \(\pm\) 0.00 fg & 10.83 \(\pm\) 0.51 ab & 62.89\% \(\pm\) 0.02 ab & 61.29\% \(\pm\) 0.01 abc \\ (Ce.Hg)-10-Sc & 9.99 \(\pm\) 0.76 acb & 0.87 \(\pm\) 0.02 e & 4.03 \(\pm\) 0.00 fg & 10.67 \(\pm\) 0.18 bc & 63.48\% \(\pm\) 0.02 a & 61.50\% \(\pm\) 0.01 abc \\ (Hg.Ht)-10-Sc & 9.95 \(\pm\) 0.68 abc & 1.50 \(\pm\) 0.02 f & 4.05 \(\pm\) 0.01 def & 10.67 \(\pm\) 0.33 bc & 63.42\% \(\pm\) 0.01 a & 60.78\% \(\pm\) 0.01 abc \\ (Ce.Hg)-10-Sc & 9.66 \(\pm\) 0.95 bc & 0.83 \(\pm\) 0.07 g & 4.02 \(\pm\) 0.01 g & 10.19 \(\pm\) 0.24 de & 62.55\% \(\pm\) 0.02 ab & 61.93\% \(\pm\) 0.01 ab \\ Sc(Ce.Hg)-1:1 & 7.17 \(\pm\) 0.84 e & 1.50 \(\pm\) 0.07 f & 4.05 \(\pm\) 0.00 def & 10.56 \(\pm\) 0.00 bcd & 64.55\% \(\pm\) 0.02 a & 62.32\% \(\pm\) 0.01 a \\ Sc(Ce.Hg)-1:1 & 7.72 \(\pm\) 1.16 e & 1.50 \(\pm\) 0.12 f & 4.07 \(\pm\) 0.01 cd & 10.67 \(\pm\) 0.18 bc & 63.19\% \(\pm\) 0.02 then quickly removed and inserted into the injection port of the gas chromatograph-mass spectrometer at 250 \({}^{\circ}\)C for desorption for 3 min, initiating data collection simultaneously. Gas chromatography was performed using an HP-5 MS capillary column with dimensions of 30 m \(\times\) 250 \(\upmu\)m \(\times\) 0.25 \(\upmu\)m. The carrier gas used was high purity helium with a flow rate of 1.2 mL/min and a split ratio of 5:1. The temperature was initially set to 40 \({}^{\circ}\)C for 2 min, then increased to 180 \({}^{\circ}\)C at a rate of 4 \({}^{\circ}\)C per minute, where it was maintained for 2 min, before being raised to 250 \({}^{\circ}\)C at a rate of 10 \({}^{\circ}\)C per minute. The detector and ion source temperatures were adjusted to 250 \({}^{\circ}\)C and 200 \({}^{\circ}\)C, respectively, with an electron energy of 70 eV and a mass scan range of 30 to 500 amu. Retention indices (RI) were used to qualitatively identify volatile components by comparing them with the NIST 14.L database. Volatile components were quantified by utilizing cyclohexanone as an internal reference, determining the volatile compound content through normalization of GC peak areas compared to the internal standard, and calculating compound equivalents based on the internal standard concentration. The odor activity value (OAV), which is the ratio of the concentration of aroma compounds to their odor thresholds (OT), is widely used to quantify the contribution of aroma compounds.