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. 2020 Jan 18;100(5):2198–2207. doi: 10.1002/jsfa.10244

Botanical and geographical origin of Turkish honeys by selected‐ion flow‐tube mass spectrometry and chemometrics

Gulsah Ozcan‐Sinir 1, Omer U Copur 1, Sheryl A Barringer 2,
PMCID: PMC9291318  PMID: 31901138

Abstract

BACKGROUND

Honey has a very important commercial value for producers as a natural product. Honey aroma is formed from the contributions of several volatile compounds, which are influenced by nectar composition, botanical origins, and location. Selected‐ion flow‐tube mass spectrometry (SIFT‐MS) is a technique that quantifies volatile organic compounds simply and rapidly, even in low concentrations. In this study, the headspace concentration of eight monofloral (chestnut, rhododendron, lavender, sage, carob, heather, citrus, and pine) and three multiflower Turkish honeys were analyzed using SIFT‐MS. Soft independent modeling of class analogy (SIMCA) was used to differentiate honey samples based on their volatiles.

RESULTS

This study focused on 78 volatile compounds, which were selected from previous studies of selected honeys. Very clear distinctions were observed between all honeys. Interclass distances greater than 8 indicate that honeys were significantly different. Methanol and ethanol were abundant in the honeys. Chestnut honey collected from the Yalova region had the highest total concentration of volatiles followed by heather honey and chestnut honey collected from the Düzce region.

CONCLUSION

Honeys with different botanical and geographical origins showed differences in their volatile profile based on chemometric analysis. Of the honey samples, methanol, ethanol, acetoin, ethyl acetate, and isobutanoic acid had the highest discriminating power. Methanol and ethanol, and then acetic acid, were the volatiles with the highest concentrations in most honeys. © 2020 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Keywords: SIFT‐MS, honey aroma, chestnut, heather, wildflower

INTRODUCTION

Honey is one of the oldest foods in existence, and is consumed not only for its effects on health but also for its taste, nutritional value, and unique flavor. Honey contains mainly water and sugar.1 Vitamins, minerals, enzymes, free amino acids, and plentiful volatile compounds are present as secondary constituents.1 Different honeys have different minor compound compositions due to their botanical and geographical origin, harvesting season, and processing conditions. The variation in this composition can be used to identify botanical and geographical origins as well as their quality.2

Honey has a very important commercial value for producers as a natural product.3 World honey production was 1.786.996 t in 2016 and Turkey ranks second after China with 105.532 t.4 The most widely found honey types in Turkey are wildflower, pine, chestnut, thyme, linden, citrus, cotton, and sunflower honey.5

Volatile compounds present in honey are characteristic markers of botanical origin.6, 7 Various volatile compounds and representative chemical groups are present at high levels in different honeys.7 Some of the main marker compounds are 3‐hydroxy‐5‐methyl‐2‐hexanone, methyl anthranilate, and sinensal isomers in citrus honey, nerolidol oxide, coumarin, hotrienol, hexanal, and hexanol in lavender honey, and 2‐cyclopenten‐1,4‐dione, 2‐aminoacetophenone, 2‐hydroxyacetophenone, guaiacol, propyl anisol, p‐anisaldehyde, and p‐cresol in heather honey.8 Chestnut honeys are noticeable for their high concentrations of acetophenone, 1‐phenylethanol, and 2‐aminoacetophenone,7 while lilac aldehyde and 2‐aminoacetophenone are indicators for rhododendron.9 According to Tananaki et al.,10 octanal, 3‐carene, camphene, octane, nonanal, decanal, α‐pinene, β‐pinene, toluene and 1.2.3‐trimethylindene are marker compounds for pine honey. Characteristic volatiles of sage honey were tetrahydro‐2,2,5,5‐tetramethylfuran, lilac aldehyde, 2‐methylbenzene, heptanoic acid, and benzeneacetic acid.11

The evaluation of the botanical and geographical origin of honey is very complicated. The fingerprint of specific honey samples can be determined by measuring organoleptic properties, melissopalynological characteristics, and physicochemical characteristics.12 Alternative and faster methods are being considered for characterization of non‐volatile and volatile markers of unifloral honeys.6 Unifloral honey aroma is mainly formed by a nectar of the specific flower. Selected‐ion flow‐tube mass spectrometry (SIFT‐MS) is a fast and sensitive analytical technique for real‐time analysis of trace gases by using the chemical ionization of the target gases.13

The principal objective of this study was to determine if chestnut, rhododendron, lavender, sage, carob, heather, citrus, pine, and wildflower honeys can be distinguished based on their volatile organic compounds using a SIFT‐MS technique combined with multivariate statistical analysis.

MATERIALS AND METHODS

Honey samples and their botanical origin

Twelve honey samples were selected from different parts of Turkey (Table 1). Local beekeepers collected the honey from bees that were kept in hives near fields containing predominantly chestnut, rhododendron, lavender, sage, carob, heather, citrus, pine, or mixed wildflower (Table 1).

Table 1.

Botanical and geographical origin of honey samples

Botanical origin Botanical name Geographical origin (Turkey) Abbreviations
1 Chestnut/monofloral Castanea sativa Mill. Yalova CY
2 Chestnut/monofloral Castanea sativa Mill. Düzce CD
3 Rhododendron/monofloral Rhododendron ponticum L. Düzce RD
4 Lavender/monofloral Lavandula stoechas L. Burdur LB
5 Sage/monofloral Salvia officinalis L. Burdur SB
6 Carob/monofloral Ceratonia silique L. Antalya CaA
7 Heather/monofloral Calluna vulgaris L. Antalya, Alanya HA
8 Citrus/monofloral Citrus Spp. Antalya, Kumluca CiA
9 Pine/monofloral Pinus brutia L. Muğla, Köyceğiz PM
10 Wildflower/multifloral * Ardahan WA
11 Wildflower/multifloral ** Sivas WS
12 Wildflower/multifloral *** Kırşehir WK
*

Mixture of Fraxinus excelsior L., Acer platanoides L., Cirsium arvense L., Cotoneaster sp., Fraxinus excelsior L., Hedysarum varium, Lonicera caucasica, Marrubium astracanicum, Medicago sativa L., Phlomis pungens, Prunus spinosa L. subsp . dasyphylla, Rosa canina L., Rubus idaeus L., Satureja hortensis L., Tilia rubra DC subsp. caucasica, Vicia sativa L.

**

Mixture of Anthemis tinctoria L., Astragalus L., Carduus nutans L., Centaurea solstitialis L., Centaurea triumfettii, Cirsium arvense L., Cotoneaster sp., Crataegus tanacetifolia , Crataegus orientalis , Eleagnus angustifolia L., Lonicera caucasica, Marrubium astracanicum, Morus alba L., Onobrychis tournefortii, Origanum vulgare L., Quercus robur L., Rosa canina L., Rubus canescens DC, Satureja hortensis L.

***

Mixture of Acer campestre L., Anthemis tinctoria L., Carduus nutans L., Cistus sp., Cotoneaster sp., Euphorbia macroclada, Genista sessilifolia, Lamium amplexicaule L., Lonicera etrusca, Phlomis armeniaca, Rosa canina L., Rubus canescens DC, Satureja hortensis L., Xeranthemum annuum L.

Measurement of volatile concentrations

For each honey sample, 10.02 ± 0.2 g was transferred into a 500 mL Pyrex bottle and capped with an open‐top cap, lined with a polytetrafluoroethylene (PTFE)‐faced silicone septa. The samples were kept in a temperature‐controlled water bath (Precision, Jouan Inc., Winchester, VA, USA) at 50 °C for 60 min to allow equilibration of the volatiles, which were released from the honey samples into the headspace. Samples were measured in triplicate.

A selected‐ion flow‐tube mass spectrometer (SIFT‐MS, V200 Syft Technologies, Christchurch, New Zealand) was used to measure and quantify the volatile compounds in the headspace. Selected‐ion flow‐tube mass spectrometry uses chemical ionization with selected positive reagent ions, H3O+, NO+, and O2 +. The concentration of the volatiles was measured by employing the predetermined reaction rate constant for the volatile with a selected precursor ion and accounting for the dilution of the sample gas into the carrier gas (helium) in the flow tube.14 Trace volatile analyte compounds were introduced in the reactor at an optimized sample inlet flow rate of 0.35 Torr·L/s (26 cm3 min−1).

The range of the mass‐to‐charge ratio was set to 10–250 m/z, with a total SIM scan time of 120 s. The concentration of measured volatile compounds, which was calculated through known kinetic parameters, is listed in Table 2. Concentrations were measured in μg L−1 in the headspace above the honey sample. During the analysis, some compounds produce the same mass for a given precursor ion, so the interfering compounds have to be reported as a mixture. In this study, several mixtures were identified at different charge‐to‐mass ratios, such as 2‐methyl‐2‐butanol and butanoic acid at 71 m/z, acetone and isoamyl alcohol at 88 m/z, acetic acid and 2‐cyclopenten‐1,4‐dione at 90 m/z, dimethyl disulfide and phenol at 94 m/z, acetic acid and p‐cresol at 108 m/z, acetoin and ethyl acetate at 118 m/z, phenylacetaldehyde and isopropyl benzene at 120 m/z, 2‐phenylethanol and santene at 122 m/z, dimethyl trisulfide and hydroxymethylfurfural at 126 m/z, α‐pinene, β‐pinene, 2‐hydroxyacetophenone and 4‐methoxybenzaldehyde at 136 m/z, octanoic acid and nonanol at 144 m/z, and hotrienol and p‐menth‐1‐en‐9‐al at 152 m/z.

Table 2.

Kinetics parameters for SIFT‐MS analysis of selected volatile compounds in Turkish honeys

Compounds Precursor ion Product ion k (10−9 cm3 s−1) m/z
1 (E)‐2‐hexenal NO+ C6H9O+ 3.8 97
2 (E)‐2‐methyl‐2‐butenal NO+ C5H7O+ 4.0 83
3 (Z)‐3‐hexen‐1‐ol NO+ C6H10 + 2.5 82
4 1,3‐butanediol O2 + C4H8O+ 3.3 72
5 1‐hexanol NO+ C6H13O+ 2.4 101
6 1‐octen‐3‐ol H3O+ C8H15 + 3.1 111
7 1‐p‐menthen‐9‐ol NO+ C10H18O+ 2.5 154
8 2,3‐butanedione NO+ C4H6O2 + 1.3 86
9 2‐aminoacetophenone NO+ C8H9NO+ 2.4 135
10 2‐butanol O2 + C3H6 + 2.1 42
11 2‐cyclopenten‐1,4‐dione NO+ C5H4O2 + 2.5 90
12 2‐heptanol NO+ C7H14O.NO+ 3.4 144
13 2‐hydroxyacetophenone NO+ C8H8O2 + 2.5 136
14 2‐methyl‐2‐butanol H3O+ C5H11 + 2.8 71
15 2‐phenylethanol NO+ C8H10O+ 2.3 122
16 3‐methylbutanal NO+ C5H9O+ 3.0 85
17 4‐methoxybenzaldehyde NO+ C8H8O2 + 2.8 136
18 5‐methylfurfural NO+ C6H6O2 + 3.1 110
19 acetic acid NO+ NO+.CH3COOH, NO+.CH3COOH.H2O 0.9 90, 108
20 acetoin NO+ C4H8O2.NO+ 2.5 118
21 acetone NO+ C3H6O+ 1.2 88
22 alpha‐pinene NO+ C10H16 + 2.3 136
23 benzaldehyde NO+ C7H5O+ 2.8 105
24 benzyl alcohol NO+ C7H7O+ 2.3 107
25 beta‐pinene NO+ C10H16 + 2.1 136
26 butanoic acid NO+ C3H7CO+ 1.9 71
27 chloroform O2 + CH(Cl35)(Cl37) + 1.8 85
28 cis‐6‐nonen‐1‐ol NO+ C9H18O+ 2.5 142
29 coumarin O2 + C9H6O2 +, C9H6O2.H+ 2.5 146, 147
30 damascenone NO+ C3H18O+ 2.5 190
31 decanal NO+ C10H19O+ 3.3 155
32 dimethyl disulfide H3O+ (CH3)2S2.H+ 2.6 95
33 dimethyl sulfide O2 + (CH3)2S+ 2.2 62
34 dimethyl trisulfide O2 + C2H6S3 + 2.2 126
35 dodecane NO+ C12H25 + 1.5 169
36 ethanol NO+ C2H5O+, C2H5O+.H2O, C2H5O+.2H2 1.2 45, 63, 81
37 ethyl acetate O2 + C2H5O2 + 2.4 61
38 ethyl benzoate H3O+ C6H5COOC2H5.H+, C6H5COOC2H5.H+.H2O 3.1 151, 169
39 furfural NO+ C5H4O2 + 3.2 96
40 furfuryl alcohol NO+ C5H6O2 + 2.5 98
41 guaiacol NO+ C7H8O2 + 2.5 124
42 heptanal NO+ C7H13O+ 3.3 113
43 heptane H3O+ C7H16 + 0.26 119
44 heptanoic acid NO+ C7H14O2+ 2.5 130
45 hexanal NO+ C6H11O+ 2.5 99
46 hexane O2 + C6H14 + 1.76 86
47 hexanoic acid H3O+ C6H12O2.H+ 3.0 117
48 hotrienol NO+ C10H16O+ 2.6 152
49 hydroxymethylfurfural O2 + C6H6O3 +, C6H6O3.H+ 2.5 126, 127
50 isoamyl alcohol NO+ C5H12O+ 2.5 88
51 isobutyl alcohol NO+ C4H9O+ 2.4 73
52 isopropyl benzene NO+ C9H12 + 1.2 120
53 lemonol NO+ C10H17 + 2.5 137
54 lilac alcohol NO+ C10H18O2 + 2.5 170
55 lilac aldehyde NO+ C10H16O2 + 2.6 168
56 maltol NO+ C6H6O3.NO+ 2.5 156
57 menthol NO+ C10H19 +, C10H19 +.2H2O 2.6 139, 175
58 methanol H3O+ CH5O+, CH3OH2+.H2O, CH3OH.H+.(H2O)2 2.7 33, 51, 69
59 methyl anthranilate NO+ C8H9NO2+ 2.5 151
60 nerolidol oxide NO+ C15H26O2 + 2.5 238
61 nerolidol NO+ C15H26O+ 3.0 222
62 nonanal NO+ C10H18 3.2 138
63 nonane H3O+ C9H20.H3O+ 1.3 147
64 nonanol NO+ C9H20O+ 2.5 144
65 octanal NO+ C8H15O+ 3.0 127
66 octane O2 + C8H18 + 1.9 114
67 octanoic acid NO+ C8H16O2 + 2.5 144
68 p‐cresol NO+ C7H8O+ 2.2 108
69 p‐isopropenyl toluene O2 + C10H12 + 1.8 132
70 p‐menth‐1‐en‐9‐al NO+ C10H16O+ 2.5 152
71 phenol NO+ C6H6O+ 2.0 94
72 phenylacetaldehyde NO+ C8H8O.NO+ 2.5 150
73 phytalic acid NO+ C8H6O4 + 2.5 166
74 propanoic acid O2 + C2H5COOH+ 2.2 74
75 propyl anisol NO+ C10H14O+ 2.5 150
76 santene NO+ C9H14 + 2.5 122
77 toluene NO+ C7H8 + 1.7 92

Statistical analysis

The concentrations of volatile compounds were analyzed in triplicate. One‐way analysis of variance (ANOVA) using Tukey's procedure with a 95% confidence interval was performed to determine statistical differences among samples; significance was defined as P ≤ 0.05 using SPSS (version 25, SPSS Inc., Chicago, IL, USA). Multivariate statistical analysis was conducted using SIMCA with Pirouette software for Windows Comprehensive Chemometrics Modeling, version 4.0 (Infometrix Inc., Bothell, WA, USA) to identify distributions of volatiles in honey samples.

RESULTS AND DISCUSSION

Volatile composition of honeys

Many compounds have been detected in honey using different techniques. This study focused on 78 volatile compounds, which were selected from previous studies of selected honeys. Twelve honey samples of known botanical and geographical origins were analyzed (Table 3). Methanol and ethanol, as in other types of honey and food, were abundant in the analyzed samples. Even though these alcohols were commonly found in natural products due to the metabolism of yeasts,15 or reduction of aldehydes,16 they can be the most effective discriminators based on either their high volatility or discriminating power (Fig. 1). These compounds have been found to discriminate among different type of honeys, such as thyme and lavender honey.17

Table 3.

Concentration (μg L−1) of volatile compounds of honeys from different botanical origins and locations

Chestnut‐Yalova Chestnut‐Düzce Rhododendron Lavender Sage Carob Heather Citrus Pine Wildflower‐Ardahan Wildflower‐Sivas Wildflower‐Kırşehir
1 (E)‐2‐hexenal 511.23a 14.30b 9.66b 17.44b 7.40b 10.85b 28.53b 4.88b 7.73b 3.43b 7.47b 3.76b
2 (E)‐2‐methyl‐2‐butenal 3250.8a 240.77b 119.24b 57.07b 17.46b 38.32b 168.76b 30.54b 41.92b 16.02b 13.10b 10.10b
3 (Z)‐3‐hexen‐1‐ol 136.27a 49.83de 66.38cd 79.33c 36.49ef 101.09b 113.04b 20.35fg 19.27fg 8.31g 5.45g 14.59g
4 1,3‐butanediol 757.36a 86.57bc 53.84c 160.15bc 101.71bc 189.99b 133.99bc 73.47bc 68.51bc 61.68c 72.94bc 47.76c
5 1‐hexanol 145.65a 20.70c 11.30cd 57.46b 155.71a 17.84cd 18.85cd 8.04cd 10.91cd 8.82cd 11.55cd 6.21d
6 1‐octen‐3‐ol 79750a 441.60b 185.30b 69.91b 35.09b 55.66b 305.91b 75.60b 68.28b 36.32b 40.63b 25.94b
7 1‐p‐menthen‐9‐ol 165.87b 5.63c 7.60c 169.61b 352.98a 42.39c 34.54c 7.91c 19.42c 20.34c 32.16c 20.59c
8 2,3‐butanedione 179.78b 87.40e 76.94ef 109.52d 79.78ef 208.61a 200.44a 64.73fg 74.56ef 129.66c 64.20fg 51.91g
9 2‐aminoacetophenone 2376.6a 49.93b 14.63b 22.48b 25.96b 11.58b 59.36b 5.00b 6.54b 2.29b 2.22b 1.93b
10 2‐butanol 879.22a 421.14c 168.68efg 277.27de 189.31efg 604.02b 604.38b 253.44def 211.55defg 119.97g 331.65cd 136.03fg
11 2‐cyclopenten‐1,4‐dione 1058.4c 516.50de 585.63d 444.71def 341.16fg 1400.9a 1217.7b 191.93gh 387.04ef 205.55gh 1040.3c 179.91h
12 2‐heptanol 190.14a 15.42b 9.39b 12.64b 14.86b 16.98b 21.86b 6.62b 8.59b 5.81b 6.60b 5.38b
13 2‐hydroxyacetophenone 286.01b 16.65c 9.93c 578.60a 399.65b 12.82c 53.58c 9.73c 7.57c 3.96c 4.74c 2.88c
14 2‐methyl‐2‐butanol 252.61c 79.41d 30.81f 68.98de 35.35f 478.26a 288.43b 54.47def 53.69def 34.02f 70.49de 46.64ef
15 2‐phenylethanol 3397.9a 93.02b 37.93b 30.06b 25.36b 39.61b 72.50b 22.76b 29.94b 21.46b 15.04b 14.78b
16 3‐methylbutanal 174.47a 91.09c 25.05e 34.00e 23.97e 183.61a 114.35b 25.11e 69.72d 24.99e 28.75e 18.59e
17 4‐methoxybenzaldehyde 283.74b 16.51c 9.85c 574.01a 396.48b 12.72c 53.16c 9.65c 7.51c 3.93c 4.70c 2.86c
18 5‐methylfurfural 109.06a 15.05b 6.69b 20.98b 116.66a 17.83b 18.51b 6.71b 8.73b 5.83b 15.84b 5.42b
19 acetic acid 3707.9a 1495.6cd 1654.5c 1265.6cde 988.71ef 3916.7a 3428.3a 542.24f 1088.5de 579.95f 2908.1b 505.65f
20 acetoin 814.95b 230.32d 77.41fg 158.36def 159.49def 1655.8a 507.46c 101.66efg 114.08efg 39.40g 191.30de 100.25efg
21 acetone 4020.9a 1189.0c 133.05e 2063.7b 424.26de 471.51de 318.68e 266.98e 950.71c 226.45e 822.88cd 327.30e
22 alpha‐pinene 403.75b 23.50c 14.02c 816.77a 564.16b 18.09c 75.64c 13.73c 10.69c 5.60c 6.69c 4.06c
23 benzaldehyde 5720.1a 292.29b 159.32b 72.16b 39.47b 241.64b 455.33b 46.88b 99.70b 17.05b 53.24b 24.92b
24 benzyl alcohol 14383a 407.02b 215.02b 49.97b 19.03b 122.45b 726.06b 42.66b 64.02b 12.66b 22.43b 15.94b
25 beta‐pinene 382.58b 22.27c 13.28c 773.94a 534.58b 17.14c 71.68c 13.01c 10.13c 5.30c 6.34c 3.85c
26 utanoic acid 611.57c 192.25d 74.60f 167.01de 85.58f 1157.9a 698.31b 131.88def 129.99def 82.36f 170.65de 112.92ef
Chestnut‐Yalova Chestnut‐Düzce Rhododendron Lavender Sage Carob Heather Citrus Pine Wildflower‐Ardahan Wildflower‐Sivas Wildflower‐Kırşehir
27 chloroform 3646.5a 251.17b 151.00b 237.60b 213.32b 274.09b 272.06b 157.04b 136.02b 118.52b 120.44b 80.84b
28 cis‐6‐nonen‐1‐ol 53.70b 13.71d 11.17d 23.98c 10.69d 73.33a 26.35c 8.31d 10.67d 11.37d 9.37d 13.67d
29 coumarin 2050.9a 41.39b 16.87b 19.16b 32.13b 46.06b 44.48b 11.69b 11.96b 8.73b 7.28b 7.92b
30 damascenone 22.23a 8.71bcd 6.35cd 8.01cd 8.66bcd 13.62b 10.96bc 5.66d 6.42cd 7.61 cd 5.77d 5.89d
31 decanal 50.33a 5.47c 3.80c 26.31b 39.69a 8.62c 6.76c 3.54c 4.03c 4.12c 4.21c 3.71c
32 dimethyl disulfide 26833a 140.95b 48.05b 44.12b 14.49b 45.64b 118.12b 14.52b 12.53b 8.86b 17.07b 5.08b
33 dimethyl sulfide 1447.9a 169.72d 102.26d 161.48d 135.36d 254.61bcd 396.17bc 469.57b 194.09cd 109.46d 150.54d 157.87d
34 dimethyl trisulfide 750.75a 35.97b 32.14b 96.89b 132.58b 58.82b 56.54b 32.68b 31.56b 28.57b 37.09b 27.95b
35 dodecane 393.64b 36.73c 32.67c 320.92b 23.23c 612.25a 348.46b 43.67c 21.75c 21.20c 12.46c 13.23c
36 ethanol 255571a 72135b 54791c 24578def 5996.2g 19492ef 66825bc 31769de 34235d 2465.4g 4227.8g 11994fg
37 ethyl acetate 1077.9b 304.66d 102.39fg 209.48def 210.97def 2190.2a 671.24c 134.46efg 150.91efg 52.11g 253.05de 132.60efg
38 ethyl benzoate 8035.1a 59.03b 75.88b 40.28b 25.84b 44.78b 67.80b 85.78b 29.39b 22.02b 17.02b 12.46b
39 furfural 409.49a 23.09d 18.53d 201.01b 54.19cd 49.41cd 65.10cd 16.33d 32.33d 25.32d 82.90c 23.10d
40 furfuryl alcohol 232.70a 60.77b 17.33c 15.82c 26.67c 24.12c 21.98c 8.25c 17.00c 6.59c 29.18bc 7.45c
41 guaiacol 24.55a 6.20de 5.01de 13.01b 11.00bc 7.73cd 5.91de 4.14de 5.98de 5.14de 4.83de 3.87e
42 heptanal 66.38a 16.81c 11.67c 16.52c 16.07c 34.03b 19.91c 9.07c 13.59c 13.08c 11.17c 14.55c
43 heptane 26034a 356.61b 170.89b 250.61b 175.48b 191.74b 506.44b 94.52b 152.05b 80.83b 144.31b 63.46b
44 heptanoic acid 84.37a 39.72b 27.74bc 33.89bc 24.58bc 32.36bc 27.69bc 22.08c 29.87bc 33.79bc 33.86c 20.52bc
45 hexanal 92.95a 28.31e 20.51efg 45.74d 78.18b 59.64c 27.17ef 11.62g 17.15fg 12.18g 18.75efg 10.35g
46 hexane 1523.9a 212.59bcd 145.33cd 285.60bcd 166.75cd 391.68bc 447.35b 155.27cd 165.56cd 185.42cd 138.98d 116.88d
47 hexanoic acid 4595.9a 116.13b 62.45b 82.39b 41.91b 119.65b 128.24b 47.55b 52.92b 44.75b 42.51b 34.52b
48 hotrienol 101.36bc 13.75c 14.30c 193.68b 501.89a 23.91c 17.86c 15.81c 15.36c 9.71c 16.00c 8.86c
49 hydroxymethylfurfural 1694.2a 32.68b 27.53b 82.47b 66.06b 44.75b 51.58b 24.31b 23.97b 19.43b 26.05b 18.86b
50 isoamyl alcohol 1913.9a 564.05c 63.09e 978.32b 201.24de 223.52de 151.38e 126.66e 450.72c 107.33e 390.23cd 155.16e
51 isobutyl alcohol 18581a 387.24b 170.24b 52.87b 19.90b 103.67b 477.65b 81.01b 78.82b 22.29b 49.95b 30.45b
52 isopropyl benzene 440.40a 53.87cd 33.81d 82.20bcd 122.60b 88.46bc 81.83bcd 94.00bc 45.60cd 45.76cd 35.50d 116.69b
53 lemonol 18338a 162.01b 53.86b 493.91b 188.40b 10.22b 139.64b 13.95b 21.94b 16.03b 6.23b 10.91b
Chestnut‐Yalova Chestnut‐Düzce Rhododendron Lavender Sage Carob Heather Citrus Pine Wildflower‐Ardahan Wildflower‐Sivas Wildflower‐Kırşehir
54 lilac alcohol 35.71b 9.77c 8.37c 29.18b 8.35c 49.88a 29.27b 7.54c 8.52c 8.27c 6.05c 6.62c
55 lilac aldehyde 65.37a 5.18f 7.39ef 24.71c 6.87ef 14.86de 35.16b 18.85cd 4.37f 5.79ef 7.12ef 5.22f
56 maltol 62.02b 22.43e 29.22de 86.34a 35.92d 77.60a 48.85c 31.76de 23.80e 23.26e 39.48cd 21.29e
57 menthol 96905a 98.89b 35.92b 55.62b 53.41b 28.70b 95.57b 16.23b 19.99b 13.48b 13.13b 12.34b
58 methanol 13011a 5453.16ef 2659.7h 4812.8fg 4539.2fg 7437.1cd 6325.8de 2699.1h 8611.5bc 4838.0fg 8833.9b 3828.3gh
59 methyl anthranilate 330.50a 6.06b 6.88b 14.92b 13.90b 7.97b 9.23b 15.67b 3.10b 1.34b 1.21b 1.42b
60 nerolidol oxide 5.59a 2.19b 1.94b 1.88b 2.49b 1.97b 1.51b 1.41b 1.83b 1.93b 1.77b 1.37b
61 nerolidol 4.23a 1.57bcd 1.09cd 1.18cd 3.11ab 2.77abc 1.25bcd 1.05cd 1.11cd 1.35bcd 0.80d 0.94cd
62 nonanal 15035a 179.67b 79.23b 303.33b 97.16b 249.98b 325.49b 48.67b 67.08b 35.51b 43.67b 38.41b
63 nonane 7288.7a 118.15b 58.74b 61.42b 41.08b 99.86b 110.54b 31.47b 42.13b 29.21b 28.86b 23.43b
64 nonanol 103.86a 23.72b 20.34b 27.48b 18.52b 19.45b 21.22b 15.68b 18.76b 27.18b 17.52b 20.44b
65 octanal 158.50a 12.84b 11.50b 22.72b 14.79b 17.84b 21.17b 11.95b 11.80b 10.38b 17.77b 9.08b
66 octane 564.11a 66.00b 48.70b 60.37b 43.10b 59.44b 64.67b 34.97b 47.78b 46.66b 45.17b 38.29b
67 octanoic acid 103.86a 23.72b 20.34b 27.48b 18.52b 19.45b 21.22b 15.68b 18.76b 27.18b 17.52b 20.44b
68 p‐cresol 314.18a 24.90b 11.36b 12.37b 16.79b 10.30b 18.68b 3.72b 5.50b 3.67b 7.45b 2.42b
69 p‐isopropenyl toluene 509.32a 49.59b 13.40b 11.52b 6.88b 18.51b 15.21b 6.45b 9.62b 10.36b 6.42b 6.28b
70 p‐menth‐1‐en‐9‐al 105.42bc 14.29c 14.87c 201.43b 521.96a 24.87c 18.58c 16.45c 15.97c 10.10c 16.64c 9.22c
71 phenol 32200a 169.14b 57.66b 52.95b 17.38b 54.77b 141.75b 17.43b 15.04b 10.63b 20.49b 6.09b
72 phenylacetaldehyde 211.39a 25.86cd 16.23d 39.46bcd 58.85b 42.46bc 39.28bcd 45.12bc 21.89cd 21.97cd 17.04d 56.01b
73 phytalic acid 37.09a 3.38c 2.87c 32.63a 22.51b 5.42c 6.80c 3.42c 2.79c 3.55c 2.61c 2.64c
74 propanoic acid 5329.5a 207.51b 56.07b 61.61b 43.09b 272.19b 179.76b 41.94b 64.48b 40.49b 64.49b 37.38b
75 propyl anisol 116.41a 9.38cd 24.81b 15.01bcd 16.21bc 7.81cd 6.48cd 8.99cd 9.84cd 5.63cd 3.92d 10.31cd
76 santene 259.19a 30.71b 19.90b 12.70b 12.95b 16.44b 12.65b 13.61b 12.42b 16.42b 9.68b 8.05b
77 toluene 8161.9a 515.01b 244.24bc 117.79bc 49.25bc 43.65bc 432.70bc 86.34bc 80.62bc 10.18c 15.93c 23.08c

Superscript letters in the row indicate statistically significant differences (P < 0.05).

Figure 1.

Figure 1

Soft independent modeling of class analogy (SIMCA) 3D projection plots of data collected by SIFT‐MS for Turkish honeys. The SIMCA plots and boundaries marked around the sample clusters represent a 95% confidence interval for each class. Interclass distances between 12 honeys based on the SIMCA class projections.

Acetic acid was the third highest concentrated volatile followed by methanol and ethanol in the honeys, except for chestnut honeys from Yalova region and lavender (Table 3). Acetic acid is formed through degradation of alcohols and produce acidic aroma in honey.18 Menthol was the second highest compound for chestnut honey from Yalova and phenol was third followed by 1‐octen‐3‐ol. The acetone concentration was the third highest in lavender honey. Menthol is a mint essential oil, which is allowed to be used in formulations against mites and ticks.19

Acetone was the fourth highest volatile of chestnut_Düzce, pine, wildflower_Ardahan and wildflower_Kırşehir, while 2‐cyclopenten‐1,4‐dione was the fourth leading volatile compound for rhododendron, heather and wildflower_Sivas. Alpha‐pinene was the fourth higest concentrated compound measured in sage honey, while ethyl acetate was measured in carob and dimethyl sulfide in citrus as fourth highest compound. Acetone is responsible for a pungent or fruity odor and ethyl acetate gives a fruity aroma in honey.20 In the presence of ethanol, ethyl acetate is formed through esterification of acetic acid via microorganisms.21 Alpha‐pinene was one of the compounds detected in the honey profile that comes directly from the flower.22

Ethyl acetate, which is the ester formed from ethanol and acetic acid, was one of the most abundant compounds in carob honey after ethanol, methanol, and acetic acid. Some studies have focused on the volatile compounds found in carob;23, 24 however, only one published article focused on the volatile characteristics of carob honey, which is mainly characterized by nonanal and octanal.25 Heather, citrus, wildflower honey from Sivas, and wildflower honey from Kırşehir also had high amounts of ethyl acetate.

Dimethyl sulfide was one of the compounds with the highest concentration detected in citrus after ethanol, methanol, and acetic acid. It was also found in both raw and heat‐treated citrus honey from Spain.26 The concentration of dimethyl sulfide was relatively high in rare unifloral honeys in Spain such as Persea americana (38.5%), Spartocytisus supranubius (25.2%), Quercus ilex (7.4–337%), Satureja montana (22.8%), and Agave honey (19.4%).27

Hotrienol is one of the marker volatiles for lavender honey;8, 28 however, in our study it was of a lower concentration compared to other compounds. Sage honey had a significantly higher amount of hotrienol than other honeys (Table 3); however, previous studies did not report it in sage honey.11, 29 The geographic areas of the lavender and sage honey were in the same province, which may lead the bees harvesting from both area and caused similarities in volatile composition. Hotrienol comes from the flower, during ripening of the honey in the hive and is thermally generated during pasteurization.30

Several alcohols were identified in lavender honey, and ethanol, methanol, isoamyl alcohol, lemonol, 2‐butanol, hotrienol and 1,3‐butanediol were the highest concentrations. Radovic et al.31 determined that ethanol, 2‐methyl‐1‐propanol, 3‐methyl‐1‐butanol, 3‐methyl‐3‐buten‐1‐ol, hotrienol, and furfuryl alcohol were the main alcohols present in lavender honey collected from France and Portugal.

Effect of botanical and geographical origins

Multivariate statistical analyses allow the determination of botanical and geographical discrimination between honey samples. Interclass distances (ICDs) greater than 3 indicate that samples were significantly different.32 Better separation of honeys is achieved with higher interclass distances between two honeys. All of the ICD values of measured honeys were greater than 3, or, in this case, greater than 8 (Fig. 1), which indicates that these honey samples can be discriminated based on their volatile composition. Ethanol and methanol showed the highest discriminating power (Table 4). Because ethanol and methanol had the highest concentration of volatiles, they may cause a decrease in discriminating power, by repressing the influence of other volatiles on the volatile profile. Multivariate statistical analysis was therefore also applied to the data set without ethanol and methanol (Fig. 2). After exclusion of these two compounds, menthol, dimethyl disulfide, phenol and dimethyl sulfide showed the highest discriminating power (Table 5). Langford et al.33 also identified dimethyl disulfide as the compound with the highest discriminating power in monofloral New Zealand honeys.

Table 4.

Discriminating power of volatile compounds of Turkish honeys

Compounds DP (102) Compounds (continued) DP (102) Compounds (continued) DP (102)
1 methanol 72 19 hexanal 0.4 37 2‐heptanol 0.2
2 ethanol 21 20 acetone 0.4 38 propyl anisol 0.2
3 acetoin 16 21 isoamyl alcohol 0.4 39 2‐phenylethanol 0.2
4 ethyl acetate 16 22 vvenzyl alcohol 0.4 40 2‐aminoacetophenone 0.2
5 isobutanoic acid 16 23 1,3‐butanediol 0.3 41 heptane 0.2
6 2‐methyl‐2‐butanol 15 24 furfural 0.3 42 cis‐6‐nonen‐1‐ol 0.2
7 butanoic acid 15 25 2‐butanol 0.3 43 dimethyl trisulfide 0.1
8 2,3‐butanedione 14 26 menthol 0.3 44 nonanal 0.1
9 3‐methylbutanal 14 27 urfuryl alcohol 0.3 45 1‐octen‐3‐ol 0.1
10 dodecane 10 28 Isobutyl alcohol 0.3 46 coumarin 0.1
11 dimethyl sulfide 0.9 29 1‐hexanol 0.3 47 p‐cresol 0.1
12 acetic acid 0.8 30 benzaldehyde 0.3 48 p‐menth‐1‐en‐9‐al 0.1
13 2‐cyclopenten‐1,4‐dione 0.7 31 hexane 0.2 49 hotrienol 0.1
14 (E)‐2‐methyl‐2‐butenal 0.7 32 maltol 0.2 50 hydroxymethylfurfural 0.1
15 toluene 0.5 33 (E)‐2‐hexenal 0.2 51 lilac alcohol 0.1
16 phenol 0.5 34 nonane 0.2 52 octanal 0.1
17 dimethyl disulfide 0.5 35 propanoic acid 0.2
18 (Z)‐3‐hexen‐1‐ol 0.5 36 lemonol 0.2

Figure 2.

Figure 2

Soft independent modeling of class analogy (SIMCA) 3D projection plots of data collected by SIFT‐MS for Turkish honeys (methanol and ethanol excluded). Boundaries marked around the honey clusters represent a 95% confidence interval. Interclass distances between 12 honeys are based on the SIMCA class projections.

Table 5.

Discriminating power of volatile compounds of Turkish honeys (methanol and ethanol excluded)

Compounds DP (102) Compounds (continued) DP (102) Compounds (continued) DP (102)
1 menthol 42 19 propanoic acid 2.1 37 furfural 1.3
2 dimethyl disulfide 11 20 p‐cresol 2.0 38 furfuryl alcohol 1.2
3 phenol 11 21 2‐methyl‐2‐butanol 1.9 39 lemonol 1.2
4 dimethyl sulfide 10 22 butanoic acid 1.9 40 1,3‐butanediol 1.2
5 benzaldehyde 9.0 23 2‐aminoacetophenone 1.9 41 heptane 1.1
6 p‐menth‐1‐en‐9‐al 8.2 24 hydroxymethylfurfural 1.9 42 p‐isopropenyl toluene 1.1
7 p‐mentha‐1(7),8(10)‐dien‐9‐ol 8.2 25 acetone 1.9 43 methyl anthranilate 0.8
8 hotrienol 8.2 26 isoamyl alcohol 1.9 44 2‐phenylethanol 0.8
9 toluene 6.3 27 decanal 1.8 45 (E)‐2‐hexenal 0.8
10 2,3‐butanedione 5.4 28 isobutyl alcohol 1.7 46 ethyl benzoate 0.7
11 1‐p‐menthen‐9‐ol 5.0 29 isobutanoic acid 1.7 47 damascenone 0.7
12 acetoin 4.9 30 2‐cyclopenten‐1,4‐dione 1.7 48 hexanoic acid 0.7
13 ethyl acetate 4.9 31 acetic acid 1.7 49 (Z)‐3‐hexen‐1‐ol 0.7
14 1‐octen‐3‐ol 4.2 32 2‐butanol 1.7 50 lilac aldehyde 0.7
15 (E)‐2‐methyl‐2‐butenal 4.0 33 dodecane 1.6 51 cis‐6‐nonen‐1‐ol 0.6
16 benzyl alcohol 3.8 34 nonanal 1.6 52 2‐hydroxyacetophenone 0.6
17 5‐methylfurfural 2.8 35 hexane 1.5
18 dimethyl trisulfide 2.5 36 3‐methylbutanal 1.5

When comparing different botanical sources from the same province, chestnut and rhododendron (Düzce), lavender and sage (Burdur), and carob, heather, and citrus (Antalya) showed clear differentiation (Fig. 1). The concentrations of 2‐butanol, 2‐methyl‐2‐butanol, 3‐methylbutanal, acetoin, acetone, butanoic acid, ethanol, ethyl acetate, furfuryl alcohol, isoamyl alcohol, isobutanoic acid, methanol, and propyl anisol were significantly different in chestnut and rhododendron (Düzce) (Table 3). Hexanal, hotrienol, and lilac aldehyde concentration were different in lavender and sage honey. Furfuryl alcohol is one of the characteristic compounds for chestnut honeys.34 Castro‐Vázquez et al.8 differentiated citrus and heather honey based on their volatile composition. Similar to our study, (Z)‐3‐hexen‐1‐ol, acetic acid, 2‐cyclopentene‐1‐4‐dione and butanoic acid were found to be higher in heather honey compared to citrus. These compounds were discriminating volatiles for heather and citrus. Even though it is difficult to determine the botanical source of honey accurately by many techniques,6 it is clearly seen that SIFT‐MS with chemometrics was effective. Agila and Barringer18 identified differences in the volatiles of honeys from different botanical sources (blueberry, clover, cranberry, and wildflowers) collected from the state of Indiana, USA. Langford et al.33 also applied SIFT‐MS technology to distinguish New Zealand monofloral honeys.

When the same flower source was compared with different locations, such as chestnut honeys from Yalova and Düzce, or wildflower honeys from three different provinces, varied volatile compositions were detected (Fig. 1). The composition of honey not only depends on the nectar‐providing plant species but also depends on other factors such as environmental factors, bee species, harvesting season and technology, processing, and storage.35 Chestnut honey collected from Yalova and Düzce regions had no statistical similarities in volatile compound concentration, except for p‐menth‐1‐en‐9‐al (Table 3). Chestnut honey from Yalova had a higher concentration of all compounds than chestnut honey from Düzce. The reason for this significant difference between the volatile levels was probably the geographical location. Castro‐Vázquez et al. 36 reported clear differentiation of chestnut honeys from different geographical origins according to their volatile composition, using multivariate statistical analysis.

The concentrations of 2,3‐butandione, 2‐butanol, 2‐cyclopenten‐1,4‐dione, acetic acid, acetoin, acetone, butanoic acid, ethyl acetate, furfural, isoamyl alcohol, isobutanoic acid, isopropyl benzene, maltol, methanol and phenylacetaldehyde were different in the three wildflower honeys from different locations. The aroma composition of wildflower honeys can be dissimilar from each other because of the variation and differences of flowers contingent upon the location.

Karabagias et al.37 investigated the geographical characterization of citrus honeys in Mediterranean countries. While ethyl acetate was determined as a key discriminating compound in citrus honeys collected from Morocco, it was not detected in honeys collected from Egypt, Greece, and Spain. Ethyl acetate was found only in Moroccan citrus honey, although ethyl octanoate and ethyl nonanoate were reported to be in higher concentration in Greek citrus honeys and ethyl nonanoate was high in Egyptian citrus honeys. Ethyl acetate may therefore be one of the compounds that can be used to geographically discriminate between Mediterranean citrus honeys.

CONCLUSION

SIFT‐MS is a fast and simple method to enhance the difference between Turkish honeys based on their volatile composition. The application of SIFT‐MS technique with the aid of chemometrics for floral and geographical origin determination of honeys can be very useful. The data analysis takes place in two‐dimensional matrices with a chemometric approach, which allows for a better separation of the samples.

Honeys with different botanical and geographical origin showed differences in their volatile profile based on their interclass distances. Between the honey samples, methanol, ethanol, acetoin, ethyl acetate, and isobutanoic acid had the highest discriminating power and also methanol and ethanol, and then acetic acid, were the volatiles at the highest concentration in most honeys. In general, chestnut from the Yalova region had the highest total concentration of volatiles followed by heather and chestnut from the Düzce region, and wildflower from the Ardahan region had the lowest total concentration.

The volatile composition of each honey type was affected by several factors. Future studies with a broader variety of honeys or geographical origins with different harvesting seasons may be required for a better understanding of the honey fingerprint.

ACKNOWLEDGEMENTS

Gulsah OZCAN‐SINIR acknowledges the Scientific and Technological Research Council of Turkey (TUBITAK) for 2219‐International Postdoctoral Research Fellowship for Turkish Citizens. The authors thank the honey collectors from different regions (Beekeping Association of Ardahan, Antalya, Düzce, Muğla, Sivas and Lisinia Nature).

Contributor Information

Gulsah Ozcan‐Sinir, Email: gulsahozcan@uludag.edu.tr.

Omer U Copur, Email: ucopur@uludag.edu.tr.

Sheryl A Barringer, Email: barringer.11@osu.edu.

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