## 2 Results
### Untargeted Metabolomics of Green and White Asparagus Spears
#### 2.1.1. Volatile Secondary Metabolites in Green and White Asparagus  
In total, 104 VOCs were detected in the headspace of green and white asparagus samples from the two harvest years, of which 88 were identified (including 61 common metabolites from 2019 and 2020). Of these 88 VOCs, 33 were unambiguously identified and 55 were tentatively annotated. The asparagus volatile profile mainly consisted of alcohols, aldehydes, esters, ketones and short-chain fatty acids with 2-13 C atoms (C\({}_{2}\)-C\({}_{13}\)). Furthermore, 9 monoterpends and 10 benzene derivatives were tentatively identified. Other identified VOCs included 5 sulfur-containing compounds (S-compounds), namely methanethol, dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide and methanethol, together with 4 furans and 2 methoxyprazines (Tables S1 and S2). The abundances of \(>\)60% of the detected VOCs in both years were significantly different between the two asparagus types (Table S3). The VOCs detected in both years as being discriminatory for the two types are summarised in Table 1a. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{1}{c}{**(a) Volatiles**} & \multicolumn{4}{c}{**(a) Volatiles**} \\ \hline
**Metabolite Name** & **CAS** & **RI** & **LOI** & **Metabolite Name** & **CAS** & **RI** & **LOI** \\ \hline \multicolumn{1}{c}{**Significantly More Abundant in Green**} & \multicolumn{4}{c}{**Significantly More Abundant in White**} & \\ \hline Methanethiol & 74-93-1 & 548 & 1 & Hexanal & 66-25-1 & 794 & 1 \\ Pentane & 109-66-0 & 567 & 1 & 1,3-Dimethybenzene & 108-38-3 & 872 & 2 \\
2-Methyl-3-butten-2-ol & 115-18-4 & 623 & 1 & 2-Heptname & 110-43-0 & 890 & 2 \\
2-Methylfuran & 534-22-5 & 623 & 1 & Hexanoic acid & 142-62-1 & 964 & 3 \\
1-Penten-3-ol & 616-25-1 & 678 & 1 & 2-Pentylfuran & 3777-69-3 & 993 & 1 \\
3-Pentanone & 96-22-0 & 689 & 2 & unidentified & - & 1050 & 4 \\ Pentanal & 110-62-3 & 692 & 1 & 1,3-Diethylbenzene & 108-38-3 & 1056 & 1 \\
1-Pentanol & 71-41-0 & 758 & 1 & (E)-2-Octenal & 2548-87-0 & 1062 & 1 \\
3-Methylbutanoic acid & 503-74-2 & 824 & 3 & 1,2-Dimethybenzene & 91-16-7 & 1146 & 1 \\ (E)-2-Hexenal & 6728-26-3 & 850 & 1 & (E,E)-2,4-Nonadienal & 5910-87-2 & 1223 & 2 \\
3-Methylhexanal & 19269-28-4 & 864 & 2 & (E,E)-2,4-Decadional & 25152-84-5 & 1325 & 2 \\ Heptanal & 111-71-7 & 900 & 1 & 2,6-Di-tert-butylbenzoquinone & 719-22-2 & 1477 & 3 \\ Octanal & 124-13-0 & 968 & 1 & & & & \\
1-Octen-3-one & 4312-99-6 & 977 & 2 & & & & \\
6-Methyl-5-hepten-2-one & 110-93-0 & 984 & 1 & & & & \\ \hline \multicolumn{1}{c}{**(b) Non-Volatiles**} & \multicolumn{4}{c}{**(b) Non-Volatiles**} & \multicolumn{4}{c}{**(c)**} & \multicolumn{4}{c}{**(d)**} \\ \hline
**Metabolite Name** & **CAS** & **M** & **LOI** & **Metabolite Name** & **CAS** & **M** & **LOI** \\ \hline \multicolumn{1}{c}{**Detected only in green**} & \multicolumn{4}{c}{**Detected only in white**} & \\ \hline Unidentified & 356.1116 & 4 & Furostane-3,22,26-triol & 1052.541 & 2 \\
3-O-Feruloylquinic acid & 1899-29-2 & 368.1113 & 2 & Unidentified & 1050.525 & 4 \\ Nicotiflorin & 31921-42-3 & 594.1594 & 2 & Spirotane-3,17-diol & 756.4305 & 2 \\ Kaempfer-sinopoly-trihexose & 978.2655 & 3 & Shatavarin VI OR V & 886.4996 & 3 \\ Blumenol C glucose & 62512-23-6 & 372.2211 & 3 & Spirot-5-ene-3,21-diol & 884.4779 & 3 \\ Ononin & 486-62-4 & 430.1271 & 3 & & & \\ \hline \multicolumn{1}{c}{**Significantly ore abundant in green**} & \multicolumn{4}{c}{**Significantly more abundant in white**} & \\ \hline Chlorogenic acid & 906-33-2 & 354.0957 & 2 & Unidentified & 682.2542 & 4 \\
3-p-Coumaroylquinic acid & 87099-71-6 & 338.1008 & 2 & Unidentified & 265.9923 & 4 \\ Asparagusic acid ester isomer II & 312.0399 & 3 & Unidentified & 674.3497 & 4 \\ Asparagusic acid ester isomer IV & 312.0399 & 3 & Prodiodiscn & 55056-80-9 & 1048.547 & 2 \\ Unidentified & 432.2002 & 4 & Shatavarin IX & 902.4943 & 2 \\ Unidentified & 430.1903 & 4 & Desglucomusennin & 868.4888 & 3 \\ \hline \hline \end{tabular}
\end{table}