A high-resolution Orbitrap Mass spectral library for trace volatile compounds in fruit wines.

The overall aroma is an important factor of the sensory quality of fruit wines, which attributed to hundreds of volatile compounds. However, the qualitative determination of trace volatile compounds is considered to be very challenging work. GC-Orbitrap-MS with high resolution and high sensitivity provided more possibilities for the determination of volatile compounds, but without the high-resolution mass spectral library. For accuracy of qualitative determination in fruit wines by GC-Orbitrap-MS, a high-resolution mass spectral library, including 76 volatile compounds, was developed in this study. Not only the HRMS spectrum but also the exact ion fragment, relative abundance, retention indices (RI), CAS number, chemical structure diagram, aroma description and aroma threshold (ortho-nasally) were provided and were shown in a database website (Food Flavor Laboratory, http://foodflavorlab.cn/ ). HRMS library was used to successfully identify the volatile compounds mentioned above in 16 fruit wines (5 blueberry wines, 6 goji berry wines and 5 hawthorn wines). The library was developed as an important basis for further understanding of trace volatile compounds in fruit wines.

Background & Summary

Among the hundreds of volatile compounds detected in fruit wines, only a small percentage of them could play key roles in the contribution of characteristic aroma[1]. Currently, the gas chromatograph-mass spectrometer has been widely used for the identification and quantification of aroma compounds. The quadrupole mass spectrometer (qMS) could be the most common mass spectrometer for analysis[2-6]. However, some trace analytes were difficult to be detected using qMS due to their low resolution and sensitivity[4,7-12]. These trace compounds needed to be identified by other detectors. The aldehydes and ketones could be detected in Syrah wines[13] and model wine solution by flame ionization detector (FID)[14,15]. The flame photometry (FPD) was used to identify sulfur compounds in Cabernet Sauvignon wines[16,17]. Besides, sulphur chemiluminescence (SCD)[13,18,19] and pulsed flame photometry (PFPD)[20,21] also could be used for the analysis of sulfur compounds in grape wines. The pyrazines could be identified in wines[22] and oak woods[23] by nitrogen-phosphorous detection (NPD). The triple-quadrupole mass spectrometer (QqQ-MS) in selected-reaction-monitoring (SRM) could identify lactones[24], terpenes[25] and sulfur compounds[26] in wines. Thus, multiple methods had to be used for the detection of various aroma compounds[14,16]. Meanwhile, the use of multiple instruments is time-consuming and costly. And it is also difficult to have so many instruments in a same laboratory. And it is an urgent challenge to identify trace aroma volatile compounds mentioned above simply and effectively in fruit wines.

In recent years, high-resolution mass spectrometry, such as quadrupole-time-of-flight-MS (Q-TOF), could improve the accuracy of identification[22,23,27]. Since Orbitrap-MS technology invented by Alexander Makarov was first commercially available in 2005, this new technique of high resolution and high sensitivity mass spectrometry has been shown great advantages for qualitative and quantitative analysis of compounds[28-30], and therefore many studies have been focused on metabolomics using liquid chromatography coupling[31-34]. After GC was coupled with Orbitrap-MS in 2015, its resolution could reach 60,000 (219 m/z, FWHM), mass accuracy could reach 1 ppm, and sensitivity could reach femtogram level, which provided more possibilities to advance the depth and breadth of GC-MS technology[35,36]. At present, GC-Orbitrap-MS began to be used to detect pesticide residues[37], nitrosamines in children’s products[38], persistent organic pollutants in the environment[39], soluble and extractable substances in package materials[40], stimulants and banned substances in urine[41] and metabonomics[42]. GC-Orbitrap-MS can provide accurate qualitative quantification of benzene compounds in chili peppers[43]. In summary, the GC-Orbitrap-MS could be a potential technique for the determination of aroma volatile compounds in fruit wines due to its high resolution and high sensitivity.

At present, the NIST library is widely used for the identification of aroma volatile compounds analyzed by gas chromatography-mass spectrometry[7,8,44,45]. However, the mass spectrums in the NIST library were mostly obtained by low-resolution mass spectrometry. There were differences in ion fragments and ion abundance between high-resolution mass spectrums obtained by GC-Orbitrap-MS and low-resolution mass spectrums obtained by GC-Quadrupole-MS[46], which led to the qualitative inaccuracy. The high-resolution mass spectrometry (HRMS) spectrums of aroma compounds analyzed by GC-Orbitrap-MS need to be established for accurate identification. In addition, the basic information of aroma compounds, such as CAS number, chemical structure diagram, aroma description and aroma threshold (ortho-nasally), need to be acquired by a large collection of literature. Thus, there is an urgent need to establish a library of HRMS spectrum and basic information to facilitate analyzing and consulting by scholars all over the world.

Methods

Overview of the experimental design

Materials and methods

Chemical and reagents

The information of standards was shown in Table 1. The individual stock solution of each standard is dissolved in ethanol and stored at −20 °C.

Table 1

The information of standards used in this study.

Compounds	CAS No.	Purity	Manufacturer	Formula	RI	Contenth/μg.L−1
Ester
Ethyl butanoate	105-54-4	≥99.5%	Aladdinb	C6H12O2	1065	10020
Ethyl 2-methylbutanoate	7452-79-1	>98.0%	Aladdin	C7H14O2	1077	5030
Ethyl isovalerate	108-64-5	>99.0%	Adamasc	C7H14O2	1093	11050
Isoamyl acetate	123-92-2	≥99.5%	Macklin	C7H14O2	1139	11390
Methyl caproate	106-70-7	>99.0%	Macklin	C7H14O2	1200	5120
Ethyl hexanoate	123-66-0	>99.0%	Aladdin	C8H16O2	1243	30300
Ethyl heptanoate	106-30-9	≥99.5%	Macklin	C9H18O2	1340	5050
Ethyl lactate	97-64-3	≥99.0%	Macklin	C5H10O3	1350	50810
Heptyl acetate	112-06-1	≥98.0%	TCI	C9H18O2	1380	3280
Methyl octanoate	111-11-5	≥99.0%	Adamas	C9H18O2	1394	2000
Ethyl caprylate	106-32-1	>99.0%	Aladdin	C10H20O2	1439	29670
Ethyl 3-hydroxybutyrate	5405-41-4	>99.0%	Macklin	C6H12O3	1511	15170
Ethyl nonanoate	123-29-5	≥95.0%	Macklin	C11H22O2	1521	7250
Ethyl 2-hydroxy-4-methylpentanoate	10348-47-7	≥98.0%	Aladdin	C8H16O3	1525	10180
Ethyl caprate	110-38-3	>99.0%	Macklin	C12H24O2	1572	20980
Ethyl succinate	123-25-1	≥99.5%	Macklin	C8H14O4	1592	50360
Methyl salicylate	119-36-8	≥99.5%	Macklin	C8H8O3	1675	4760
Ethyl benzeneacetate	101-97-3	≥99.5%	Aladdin	C10H12O2	1689	1940
Ethyl salicylate	118-61-6	>99.0%	Aladdin	C9H10O3	1710	5480
Ethyl hydrocinnamate	2021-28-5	>98.0%	TCId	C11H14O2	1785	12040
Ethyl cinnamate	103-36-6	>98.0%	Adamas	C11H12O2	2031	5040
Monoethyl succinate	1070-34-4	>95.0%	Aladdin	C6H10O4	2308	11020
Carbonyl compounds
(E)-2-Hexenal	6728-26-3	>98.0%	Aladdin	C6H10O	1329	7120
(E)-2-Heptenal	18829-55-5	>95.0%	Aladdin	C7H12O	1362	6530
(E)-2-Octenal	2548-87-0	>95.0%	Macklin	C8H14O	1432	1900
(E,E)-2,4-Heptadienal	4313-03-5	>90.0%	Macklin	C7H10O	1498	10220
(E,Z)-2,6-Nonadienal	557-48-2	≥95.0%	Aladdin	C9H14O	1545	4160
Benzeneacetaldehyde	122-78-1	>95.0%	Macklin	C8H8O	1574	5720
High alcohols
Isobutanol	78-83-1	≥99.5%	Aladdin	C4H10O	1112	20620
Isoamylol	123-51-3	≥99.5%	Aladdin	C5H12O	1217	78820
1-Pentanol	71-41-0	≥99.5%	Macklin	C5H12O	1259	6340
2-Heptanol	543-49-7	>98.0%	Aladdin	C7H16O	1327	8700
3-Octenol	3391-86-4	>98.0%	Aladdin	C8H16O	1456	3220
1-Heptanol	111-70-6	>95.0%	Macklin	C7H16O	1460	5490
2-Nonanol	628-99-9	≥98.0%	Aladdin	C9H20O	1511	3240
1-Octanol	111-87-5	≥99.5%	Macklin	C8H18O	1532	9060
2-Phenylethanol	60-12-8	≥99.5%	Aladdin	C8H10O	1817	50690
2-Phenoxyethanol	122-99-6	≥ 99.5%	Macklin	C8H10O2	2043	9900
Lactone
γ-Octalactone	104-50-7	>98.0%	Sigma-Aldrich	C11H20O2	1814	4140
δ-Octalactone	698-76-0	>98.0%	Sigma-Aldrich	C8H14O2	1862	3480
γ-Nonalactone	104-61-0	>98.0%	Sigma-Aldrich	C8H14O2	1925	3260
Pantolactone	599-04-2	>99.0%	Sigma-Aldrich	C6H10O3	1935	19860
γ-Decalactone	706-14-9	>98.0%	Sigma-Aldrich	C10H18O2	2041	3700
Sotolon	28664-35-9	>97.0%	Sigma-Aldrich	C6H8O3	2108	4980
γ-Undecalactone	104-67-6	>98.0%	Sigma-Aldrich	C11H20O2	2161	3520
Acid
Butanoic acid	107-92-6	≥99.5%	Sigma-Aldrich	C4H8O2	1574	30960
Hexanoic acid	142-62-1	≥99.5%	Macklin	C6H12O2	1762	25780
Ethylhexanoic acid	149-57-5	≥99.9%	Aladdin	C8H16O2	1860	10090
Octanoic acid	124-07-2	≥99.5%	Aladdin	C8H16O2	1973	56880
Decanoic acid	334-48-5	>99.0%	Aladdin	C10H20O2	2190	20170
Benzoic acid	65-85-0	≥99.9%	Aladdin	C7H6O2	2378	11630
Pyrazine
3-Isopropyl-2-methoxypyrazine	25773-40-4	>97.0%	Sigma-Aldrich	C8H12ON2	1435	1280
2-sec-Butyl-3-Methoxypyrazine	24168-70-5	>99.0%	Sigma-Aldrich	C9H14ON2	1453	980
5-Ethyl-2,3-dimethylpyrazine	15707-34-3	>98.0%	Sigma-Aldrich	C8H12N2	1459	2230
2-Isobutyl-3-methoxypyrazine	24683-00-9	>99.0%	Sigma-Aldrich	C9H14ON2	1513	1490
Acetylpyrazine	22047-25-2	>97.0%	Sigma-Aldrich	C6H6N2O	1565	2010
Furan
Furfural	98-01-1	>99.0%	Sigma-Aldrich	C5H4O2	1472	5250
Acetylfuran	1192-62-7	>99.0%	Sigma-Aldrich	C6H6O2	1505	9840
5-Methylfurfural	620-02-0	>99.0%	Sigma-Aldrich	C6H6O2	1540	1740
Ethyl 2-furoate	614-99-3	>99.0%	Sigma-Aldrich	C7H8O3	1565	4250
Furfuryl alcohol	98-00-0	>98.0%	Sigma-Aldrich	C5H6O2	1585	10820
5-Hydroxymethylfurfural	67-47-0	>99.0%	Sigma-Aldrich	C6H6O3	2415	20050
Terpenes
D-Limonene	5989-27-5	≥99.0%	TCI	C10H16	1203	1860
Terpinolene	586-62-9	>90.0%	TCI	C10H16	1284	2330
β-Linalool	78-70-6	>98.0%	Macklin	C10H18O	1527	2410
Citronellyl acetate	150-84-5	≥95.0%	Aladdin	C12H22O2	1583	3180
β-Ionone	14901-07-6	>97.0%	Aladdin	C13H20O	1833	1560
Benzene
o-Xylene	95-47-6	≥99.0%	Macklin	C8H10	1192	1520
Styrene	100-42-5	≥99.5%	Macklin	C8H8	1264	2190
p-Cymene	99-87-6	≥99.5%	Macklin	C10H14	1273	2900
Naphthalene	91-20-3	≥ 99.5%	Macklin	C10H8	1635	2070
Volatile phenol
4-Methylguaiacol	93-51-6	>99.0%	Sigma-Aldrich	C8H10O2	1860	2820
o-Cresol	95-48-7	>99.0%	Sigma-Aldrich	C7H7O	1913	4980
4-Propylguaiacol	2785-87-7	>99.0%	Sigma-Aldrich	C10H14O2	2011	5370
4-Vinylphenol	2628-17-3	>95.0%	Sigma-Aldrich	C8H8O	2306	2540
Sulfide
3-(Methylthio)propanol	505-10-2	≥99.0%	Macklin	C4H10OS	1618	6600
Internal standard
4-Methyl-2-pentanol	108-11-2	≥98.0%	CNWf	C6H14O	1065	1000

aShanghai Macklin Biochemical Co., Ltd (Shanghai, China).

bAladdin Bio-Chem Technology (Shanghai, China).

cAdamas Reagent, Co., Ltd. (Shanghai, China).

dTCI Development Co., Ltd. (Shanghai, China).

eSigma-Aldrich (St. Louis, MO, USA).

fCNW Technologies GmbH (Duesseldorf, Germany).

gBide Pharmatech Ltd. (Shanghai, China).

hThe contents of spiked standard mixtures used in direct liquid introduction method.

Wine Samples collection

Three kinds of commercial fruit wines (blueberry wine, B, goji berry wine, G and hawthorn wine, H) purchased from retail stores in China were used for the establishment of HRMS library. All blueberry samples were with an alcohol content of 12% v/v (percent by volume). Three blueberry wines were received from Beiyushidai, including blueberry dry wine produced in 2019 (B1) and 2017 (B2) and blueberry semi-dry wine produced in 2019 (B3). A blueberry dry wine (B4) was produced by Shenghua in 2019. Another blueberry dry wine (B5) produced in 2019 was provided by Yicunshanye. Goji berry semi-dry wine (G1) was produced by Ningxiahong in 2019, with an alcohol content of 7% v/v. Four batches of goji berry dry wine (G2-G5) produced by Senmiao in 2017 were with an alcohol content of 11% v/v. G6 was made by our laboratory in 2016 with an alcohol content of 11% v/v. All hawthorn wine samples were semi-dry wines from Shengbali. H1 and H2 produced in 2019 were with an alcohol content of 12% v/v. The other H3-H5 were produced in 2020 with an alcohol content of 13% v/v from Shengbali.

Preparation of the spiked mixture

The direct liquid introduction method was used to determine the mass spectral information of the target compound. The standard mixtures (Mixture 1 with 24 esters, Mixture 2 with 6 carbonyl compounds and 8 lactones and 6 acids, Mixture 3 with10 high alcohols and 6 furans and 5 pyrazines, Mixture 4 with 5 terpenes and 4 benzenes and 4 volatile phenols and 1 sulfide) were prepared to extract. The mother solution of each compound was dissolved in ethanol at higher concentration. Each standard mixtures were mixed by the mother solution of compounds according to the concentrations (Table 1).The standard mixtures were diluted with dichloromethane to volume in a 10-mL volumetric flask. 1 μL of each mixture was injected. The split mode was applied with a split ratio of 10:1. The liquid injection was performed using the TriPlus RSH autosampler (Thermo Fisher Scientific, Bremen, Germany).

Extraction of volatile compounds in wine samples

Headspace solid-phase microextraction (HS-SPME) was used to extract the volatile compounds from fruit wines. 5 mL of wine samples mixed with 1.00 g NaCl and 10 μL of internal standard (1.077 g/L 4-methyl-2-pentanol) were prepared in a 20 mL glass vial. The sample vials were stirred and heated at 60 °C for 30 min. Then the preconditioned fiber (50/30 μm Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS)) was used to absorb the volatile compounds in the headspace of the sample via for 30 min at 60 °C. After absorption, the fiber was inserted into the GC injection port for desorbing at 250 °C for 10 min. Two technical replicates were performed for each sample. Automatic headspace solid-phase microextraction was performed on the TriPlus RSH autosampler.

GC-Orbitrap-MS analysis

A Thermo Scientific Trace 1300 gas chromatography equipped with a Thermo Scientific Q-Exactive Orbitrap mass spectrometer (GC-Orbitrap MS, Thermo Scientific, Bremen, Germany) was used for detection. The spiked mixture was performed under the following GC-Orbitrap-MS conditions. A TG-WAXMS 30 m × 0.25 mm × 0.25 μm (Thermo Scientific, Bremen, Germany) was used to separate analytes. Helium was used as the carrier gas (1.2 mL/min). The oven temperature program was set as follows: 40 °C held for 5 min, then heated to 180 °C at 3 °C/min, finally increased from 180 °C to 240 °C at 30 °C/min and hold 15 min. The wine samples were performed under the following GC-Orbitrap-MS conditions. A DB-WAX 30 m × 0.25 mm × 0.25 μm (J&W Scientific, Folsom, CA, USA) was used to separate the volatile compounds under a 1.2 mL/min flow rate of helium (carrier gas).The oven temperature program was set as follows: 40°C held for 5 min, then heated to 180°C at 3 °C /min, finally increased from 180 °C to 250 °C at 30 °C/min and hold 10 min.

The Orbitrap-MS operated in full-scan MS acquisition mode (m/z 33–350). The ion source was maintained at 280 °C with an MSD transfer line temperature of 230 °C. Positive ion-electron ionization (EI) was used at 70 electron volts (eV) in Orbitrap-MS.

Identification of the compounds

Retention indices (RI) were calculated from the retention times of C6-C24 n-alkanes under the same chromatographic and mass spectrometric conditions. The high-solution mass spectrums of volatile compounds were collected in different standard mixtures. Then, the qualitative determination of target compounds in fruit wines was performed by the match of the retention time and ion fragments in samples and standards.The experimental design and analysis pipeline are shown in Fig. 1.

Fig. 1

Flowchart of the experimental design.

Data Records

A total of 36 original data files were stored in MetaboLights[47], including 4 standard mixtures and 32 wine samples (two technical replicates).

Technical Validation

Two technical replicates were performed on each wine sample. The qualitative determination of target volatile compounds in fruit wines was shown in Table 3.

Table 3

The qualitative determination of target volatile compounds in goji berry wines, blueberry wines and hawthorn wines.

Compounds	B1	B2	B3	B4	B5	G1	G2	G3	G4	G5	G6	H1	H2	H3	H4	H5
Ester
Ethyl butanoate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Ethyl 2-methylbutanoate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Ethyl isovalerate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Isoamyl acetate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Methyl caproate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Ethyl hexanoate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Ethyl heptanoate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Ethyl lactate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Heptyl acetate	√	√	√	√	√	√	√	√	√	√	nd	√	nd	nd	nd	nd
Methyl octanoate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Ethyl caprylate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Ethyl 3-hydroxybutyrate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Ethyl nonanoate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Ethyl 2-hydroxy-4-methylpentanoate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Ethyl caprate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Ethyl succinate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Methyl salicylate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	nd	√
Ethyl benzeneacetate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Ethyl salicylate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Ethyl hydrocinnamate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Ethyl cinnamate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Monoethyl succinate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Carbonyl compounds
(E)-2-Hexenal	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
(E)-2-Heptenal	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
(E)-2-Octenal	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
(E,E)-2,4-Heptadienal	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
(E,Z)-2,6-Nonadienal	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Benzeneacetaldehyde	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
High Alcohols
Isobutanol	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Isoamylol	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
1-Pentanol	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
2-Heptanol	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
3-Octenol	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
1-Heptanol	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
2-Nonanol	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
1-Octanol	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
2-Phenylethanol	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
2-Phenoxyethanol	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Lactone
γ-Undecalactone	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
δ-Octalactone	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
γ-Octalactone	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Pantolactone	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
γ-Decalactone	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Sotolon	√	√	√	√	nd	nd	√	nd	nd	√	nd	nd	nd	nd	nd	nd
γ-Nonalactone	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Acid
Butanoic acid	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Hexanoic acid	nd	√	nd	√	√	√	√	√	√	√	√	√	√	√	√	√
Ethylhexanoic acid	nd	√	nd	√	√	√	√	√	√	√	√	√	√	√	√	√
Octanoic acid	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Decanoic acid	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Benzoic acid	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Pyrazine
3-Isopropyl-2-methoxypyrazine	√	√	√	√	√	√	√	√	√	nd	√	√	√	√	nd	√
2-sec-Butyl-3-Methoxypyrazine	√	√	√	√	nd	√	√	nd	√	nd	nd	√	√	nd	√	√
5-Ethyl-2,3-dimethylpyrazine	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
2-Isobutyl-3-methoxypyrazine	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Acetylpyrazine	nd	nd	√	√	nd	nd	√	√	√	nd	nd	√	√	√	√	√
Furan
Furfural	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Acetylfuran	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
5-Methylfurfural	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Ethyl 2-furoate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Furfuryl alcohol	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
5-Hydroxymethylfurfural	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Terpenes
D-Limonene	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Terpinolene	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	nd
β-Linalool	√	√	√	√	nd	nd	√	√	√	√	nd	nd	nd	nd	√	nd
Citronellyl acetate	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
β-Ionone	√	√	√	nd	√	√	√	√	√	√	√	√	nd	√	nd	√
Benzene
o-Xylene	nd	nd	nd	nd	nd	nd	nd	nd	√	nd	nd	nd	nd	√	√	√
Styrene	√	√	√	√	√	√	√	√	√	√	√	√	nd	√	√	√
p-Cymene	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Naphthalene	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
Volatile phenol
4-Methylguaiacol	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
o-Cresol	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
4-Propylguaiacol	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√	√
4-Vinylphenol	√	√	√	√	√	nd	√	√	√	√	√	nd	nd	nd	nd	nd
Sulfide
3-(Methylthio)propanol	√	√	√	nd	√	√	√	√	√	√	√	√	√	√	√	√

‘B’ represent blueberry wine, ‘G’ represent goji berry wine, ‘H’ represent hawthorn wine.

Usage Notes

The HRMS library of volatile compounds was shown on the database website (http://foodflavorlab.cn/), including HRMS spectrum, exact ion fragment, relative abundance, RI, CAS number, chemical structure diagram, aroma description and aroma threshold (ortho-nasally). Table 1 showed CAS No., formula and RI of each target volatile compound. The information of standards and contents of spiked mixtures were shown in Table 1. Table 2 showed elemental composition judgments, exact ion fragments and error mass of each target volatile compound. Table 3 showed the qualitative determination of target volatile compounds in blueberry wine, goji berry wine and hawthorn wine. Figure 2 showed the web page of the database website (http://foodflavorlab.cn/) including the home page, upload page, search page and result page. Figure 3 showed the page view (PV) of the database website (http://foodflavorlab.cn/) from Nov. 2020 to May. 2022.

Table 2

The qualitative and quantitative information of target volatile compounds.

Compounds	Precursor ions			Quantifier ions			Qualifier ions
	Exact mass (m/z)	Molecular formula	Error mass (ppma)	Exact mass (m/z)	Molecular formula	Error mass (ppm)	Exact mass (m/z)	Molecular formula	Error mass (ppm)
Ester
Ethyl butanoate				43.05422	C3H7	−0.99526	88.05202	C4H8O2	0.7668
Ethyl 2-methylbutanoate				74.03639	C3H6O2	0.2198	102.0677	C5H10O2	0.41588
Ethyl isovalerate				57.06997	C4H9	0.34743	61.0285	C2H5O2	0.15943
Isoamyl acetate				43.01782	C2H3O	−1.06298	55.05433	C4H9	0.6148
Methyl caproate				43.01782	C2H3O	−0.70828	74.03639	C3H6O2	0.52895
Ethyl hexanoate				43.05422	C3H7	−0.99526	73.02851	C3H5O2	0.70783
Ethyl heptanoate				73.02854	C3H5O2	0.49889	88.05192	C4H8O2	0.42009
Ethyl lactate				45.03354	C2H5O	1.30819	56.0621	C4H8	0.9174
Heptyl acetate				43.01778	C2H3O	−0.17621	70.07773	C5H10	0.8118
Methyl octanoate				43.01782	C2H3O	−0.70828	74.03639	C3H6O2	0.73505
Ethyl caprylate				73.02845	C3H5O2	−0.44136	101.05977	C5H9O2	−0.43741
Ethyl 3-hydroxybutyrate				43.01778	C2H3O	−0.6196	71.01285	C3H3O2	1.29569
Ethyl nonanoate				73.02845	C3H5O2	−0.54583	101.05977	C5H9O2	−0.51291
Ethyl 2-hydroxy-4-methylpentanoate				69.06999	C5H9	0.12138	45.03355	C2H5O	1.22348
Ethyl caprate				73.02853	C3H5O2	0.39441	61.0285	C2H5O2	0.28445
Ethyl succinate				101.02348	C4H5O3	0.02484	73.02853	C3H5O2	0.60336
Methyl salicylate	152.04683	C8H8O3	0.22088	120.02077	C7H4O2	0.28082	92.02578	C6H4O	0.15454
Ethyl benzeneacetate	164.08322	C10H12O2	0.24546	91.05439	C7H7	−0.13544	136.05219	C8H8O2	0.66442
Ethyl salicylate	166.06245	C9H10O3	0.05133	120.02077	C7H4O2	0.40795	92.02578	C6H4O	0.15454
Ethyl hydrocinnamate	178.09898	C11H14O2	0.85652	104.06216	C8H8	0.34761	105.06997	C8H9	0.15241
Ethyl cinnamate	176.08331	C11H12O2	0.96579	131.04938	C9H7O	0.98604	103.05436	C8H7	0.62066
Monoethyl succinate				101.02348	C4H5O3	0.10036	73.02853	C3H5O2	0.60336
Carbonyl compounds
(E)-2-Hexenal				83.04919	C5H7O	0.17795	69.03339	C6H9O	0.46658
(E)-2-Heptenal				83.04919	C5H7O	0.54542	41.03839	C3H5	−3.22212
(E)-2-Octenal				83.04919	C5H7O	0.17795	41.03839	C3H5	−4.80235
(E,E)-2,4-Heptadienal				81.03347	C5H5O	−0.26157	109.0647	C7H9O	0.11559
(E,Z)-2,6-Nonadienal				41.03839	C3H5	−4.33758	70.04136	C4H6O	−0.48152
Benzeneacetaldehyde	120.05711	C8H8O	1.14129	91.05439	C7H7	0.61866	92.06208	C7H8	0.31004
High alcohols
Isobutanol				41.0384	C3H5	−4.52349	45.0336	C2H5O	2.32468
Isoamylol				57.0699	C4H9	0.41428	70.07784	C5H10	0.37632
1-Pentanol				57.06991	C4H9	0.54796	70.07784	C5H10	0.59406
2-Heptanol				45.03354	C2H5O	0.88465	83.08566	C6H11	0.5339
3-Octenol				57.03355	C3H5O	0.49786	85.06478	C5H9O	0.50696
1-Heptanol				43.05422	C2H3O	−1.06298	70.07338	C5H10	0.48519
2-Nonanol				105.03364	C7H5O	0.74249	122.03642	C7H6O2	0.75852
1-Octanol				69.06999	C5H9	0.23184	55.05433	C4H7	0.3996
2-Phenylethanol	122.07275	C8H10O	1.06311	91.05439	C7H7	0.95382	92.06208	C7H8	−0.51868
2-Phenoxyethanol				108.05687	C7H8O	−0.89706	94.04132	C6H6O	0.04701
Lactone
γ-Undecalactone				85.02853	C4H5O2	0.69766	95.0493	C6H7O	0.95817
δ-Octalactone				99.04407	C5H7O2	−0.11627	71.04915	C4H7O	0.74492
γ-Octalactone				85.02851	C4H5O2	−0.10989	57.03359	C3H5O	0.49786
Pantolactone				71.04915	C4H7O	0.10063	43.05414	C3H7	−2.23569
γ-Decalactone				85.02853	C4H5O2	0.1593	95.0493	C6H7O	0.47656
Sotolon	128.04693	C6H8O3	0.18604	83.04919	C5H7O	0.08357	55.05427	C4H7	0.81287
γ-Nonalactone				85.02851	C4H5O2	−0.02016	57.03359	C3H5O	0.36409
Acid
Butanoic acid				60.02063	C2H4O2	0.56154	73.02845	C3H5O2	0.39441
Hexanoic acid				73.02853	C3H5O2	0.18547	60.02069	C2H4O2	0.39361
Ethylhexanoic acid				73.02853	C3H5O2	0.18547	87.04422	C4H7O2	0.48125
Octanoic acid				73.02853	C3H5O2	0.18547	101.05988	C5H9O2	0.6195
Decanoic acid				73.02844	C3H5O2	0.49889	101.05976	C5H9O2	0.54401
Benzoic acid	122.03632	C7H6O2	0.75852	105.03364	C7H5O	0.66985	122.03642	C7H6O2	0.75852
Pyrazine
3-Isopropyl-2-methoxypyrazine	152.09455	C8H12ON2	0.50811	137.071	C7H9ON2	0.50114	124.06324	C6H8ON2	0.86187
2-sec-Butyl-3-Methoxypyrazine	166.10973	C9H14ON2	−1.99624	138.07886	C7H10ON2	0.56568	124.06321	C6H8ON2	0.75882
5-Ethyl-2,3-dimethylpyrazine	136.0996	C8H12N2	0.64728	135.0918	C8H11N2	0.714	121.07612	C7H9N2	−0.02603
2-Isobutyl-3-methoxypyrazine	166.11008	C9H14ON2	0.08705	124.0632	C6H8ON2	0.58057	95.06044	C5H7N2	−0.08289
Acetylpyrazine	122.04759	C6H6ON2	0.53454	94.0526	C5H6N2	0.35341	80.03695	C4H4N2	0.43185
Furan
Furfural	96.02053	C5H4O2	−0.84083	95.01279	C5H3O2	0.16541	39.02277	C3H3	−3.43066
Acetylfuran	110.03637	C6H6O2	0.42523	95.01281	C5H3O2	0.64721	43.01782	C2H3O	−0.41717
5-Methylfurfural	110.03625	C6H6O2	−0.47613	109.02855	C6H5O2	0.68404	53.03864	C4H5	1.24689
Ethyl 2-furoate	140.04697	C7H8O3	0.56667	95.01279	C5H3O2	−0.07548	112.01554	C5H4O3	−0.07007
Furfuryl alcohol	98.03629	C5H6O2	0.01035	97.02851	C5H5O2	0.29686	81.0336	C5H5O	0.11503
5-Hydroxymethylfurfural	126.03131	C6H6O3	0.34424	97.02849	C5H5O2	0.29686	69.03357	C4H5O	0.5771
Terpenes
D-Limonene	136.1252	C10H16	1.65914	93.07005	C7H9	1.89353	121.10146	C9H13	1.60836
Terpinolene	136.12471	C10H16	0.4261	121.10132	C9H13	0.22236	93.06999	C7H9	0.25403
β-Linalool				93.07005	C7H9	0.41798	69.03339	C5H9	0.3423
Citronellyl acetate				81.06996	C6H9	0.00931	95.08559	C7H11	−0.17538
β-Ionone				177.12753	C12H17O	0.28057	178.13091	C12H17O	−2.13518
Benzene
o-Xylene	106.07779	C8H10	−0.11101	91.05439	C7H7	0.03214	103.05429	C8H7	0.62066
Styrene	104.0621	C8H8	−0.09229	104.0621	C8H8	−0.09229	78.04652	C6H6	0.78457
p-Cymene	134.10954	C10H14	0.39181	119.0857	C9H11	0.05216	115.0543	C9H7	0.68855
Naphthalene	128.06218	C10H8	0.04416	128.06218	C10H8	0.04416	129.06557	C10H8	−3.16989
Volatile phenol
4-Methylguaiacol	138.06754	C8H10O2	0.04814	138.06754	C8H10O2	0.04814	123.04407	C7H7O2	−0.00386
o-Cresol	107.04918	C7H7O	0.20933	107.04918	C7H7O	0.20933	79.05427	C6H7	0.42305
4-Propylguaiacol	166.09877	C10H14O2	−0.18399	137.05968	C8H9O2	0.01147	122.03631	C7H6O2	0.19587
4-Vinylphenol	120.057	C8H8O	0.14583	120.057	C8H8O	0.14583	91.05425	C7H7	0.19972
Sulfide
3-(Methylthio)propanol	106.04483	C7H6O	3.52157	106.04483	C7H6O	3.52157	88.03425	C7H4	3.50426
Internal standard
4-Methyl-2-pentanol				45.03355	C2H5O	0.79994

appm means parts per million mass error.

Fig. 2

The web page of the database website (http://foodflavorlab.cn/) including the home page, upload page, search page and result page.

Fig. 3

The page view (PV) of database website (http://foodflavorlab.cn/).

Measurement(s)	volatile compounds
Technology Type(s)	GC-Orbitrap-MS