J Food Bioact

Journal of Food Bioactives, ISSN 2637-8752 print, 2637-8779 online

Journal website www.isnff-jfb.com

Original Research

Volume 20, December 2022, pages 61-71

Formation of furanoic compounds in model systems with saccharides, amino acids, and fatty acids, analyzed with headspace-solid phase micro-extraction-gas chromatography–tandem mass spectrometry

Figure 1. Levels [µmol/mol precursor] of furan, 2-methylfuran (2-MF), 3-methylfuran (3-MF), 2-ethylfuran (2-EF), 2,5-dimethylfuran (2,5-DMF), furfural (2-FA), furfuryl alcohol (2-FOL), and 2-acetylfuran (2-AF) (mean ± SD, n = 3) obtained by heat treatment of mono- and disaccharides in model A at pH 7 (a) and model B (b).

Figure 2. Levels [µmol/mol precursor] of furan, 2-methylfuran (2-MF), 3-methylfuran (3-MF), 2-ethylfuran (2-EF), furfural (2-FA), and 2-pentylfuran (2-PF) (mean ± SD, n = 3) obtained by heat treatment of the polyunsaturated fatty acids α-linolenic acid (ALA), α-linolenic acid methyl ester (ALA-ME), γ-linolenic acid (GLA), DHA ethyl ester (DHA-EE), eicosapentaenoic acid (EPA), and linoleic acid (LA) in model A at pH 7.

Figure 3. Levels [µmol/mol precursor] of furan, 2-methylfuran (2-MF), 3-methylfuran (3-MF), 2-ethylfuran (2-EF), 2,5-dimethylfuran (2,5-DMF), furfural (2-FA), furfuryl alcohol (2-FOL), and 2-acetylfuran (2-AF) (mean ± SD, n = 3) obtained by heat treatment of mixtures of (a) maltose and (b) galactose with alanine, cysteine, leucine, proline, and serine in model A at pH 7.

**Table 1.** Precursor and product ions of the GC–MS/MS method for furan, 2-methylfuran (2-MF), 3-methylfuran (3-MF), 2-ethylfuran (2-EF), 2,5-dimethylfuran (2,5-DMF), 3-furaldehyde (3-FA), furfural (2-FA), furfuryl alcohol (2-FOL), 3-furanmethanol (3-FOL), 2-acetylfuran (2-AF), and 2-pentylfuran (2-PF) and the corresponding stable isotopically substituted internal standards
Compound	Retention time [min]	Precursor ion [m/z]	Product ion [m/z]	Collision energy [eV]
Furan-d₄	5.8	72	42	22
Furan	5.8	68	39	22
2-MF-d₆	9.7	88	42	22
2-MF	9.8	82	39	18
3-MF-d₃	10.3	85	41	19
3-MF	10.4	82	39	18
2-EF-d₅	14.8	101	83	12
2-EF	15.0	96	81	12
2,5-DMF-d₃	15.2	99	43	32
2,5-DMF	15.4	96	43	31
3-FA	22.5	96	95	9
2-FA-d₃	23.3	99	98	12
2-FA	23.3	96	95	12
2-FOL-d₅	24.0	103	47	8
FOL	24.0	98	42	9
3-FOL	24.4	98	42	8
2-AF	25.2	110	95	8
2-PF	25.8	138	81	18
[¹³C₂]-2-PF	25.8	140	81	18

Table 1. Precursor and product ions of the GC–MS/MS method for furan, 2-methylfuran (2-MF), 3-methylfuran (3-MF), 2-ethylfuran (2-EF), 2,5-dimethylfuran (2,5-DMF), 3-furaldehyde (3-FA), furfural (2-FA), furfuryl alcohol (2-FOL), 3-furanmethanol (3-FOL), 2-acetylfuran (2-AF), and 2-pentylfuran (2-PF) and the corresponding stable isotopically substituted internal standards

Compound

Retention time [min]

Precursor ion [m/z]

Product ion [m/z]

Collision energy [eV]

Furan-d₄

5.8

Furan

5.8

2-MF-d₆

9.7

2-MF

9.8

3-MF-d₃

10.3

3-MF

10.4

2-EF-d₅

14.8

101

2-EF

15.0

2,5-DMF-d₃

15.2

2,5-DMF

15.4

3-FA

22.5

2-FA-d₃

23.3

2-FA

23.3

2-FOL-d₅

24.0

103

FOL

24.0

3-FOL

24.4

2-AF

25.2

110

2-PF

25.8

138

[¹³C₂]-2-PF

25.8

140

**Table 2.** Limits of detection (LOD), limits of quantification (LOQ), linearity, repeatability, and reproducibility for furan, 2-methylfuran (2-MF), 3-methylfuran (3-MF), 2-ethylfuran (2-EF), 2,5-dimethylfuran (2,5-DMF), 3-furaldehyde (3-FA), furfural (2-FA), furfuryl alcohol (2-FOL), 3-furanmethanol (3-FOL), 2-acetylfuran (2-AF), and 2-pentylfuran (2-PF)
Compound	LOD^a [ng]	LOQ^b [ng]	R^2c	RSD low conc. [%]^d	RSD high conc. [%]^e	Accuracy low conc. [%]^f	Accuracy high conc. [%]^g
^aLimit of detection (LOD) based on signal-to-noise (S/N) of ≥3; ^bLimit of quantification (LOQ) based on S/N of ≥10; ^cLinearity expressed by correlation coefficient (R²) (n = 3); ^dPrecision at low concentration levels (spiked with 10 µL of standard solution) expressed by relative standard deviation (RSD) (n = 6); ^ePrecision at high concentration levels (spiked with 500 µL of standard solution) expressed by RSD (n = 6); ^fAccuracy at low concentration levels (spiked with 10 µL of standard solution) expressed by the coefficient of determined amount and spiked amount × 100 (n = 6); ^gAccuracy at high concentration levels (spiked with 500 µL of standard solution) expressed by coefficient of determined amount and spiked amount × 100 (n = 6).
Furan	0.323	0.970	≥0.9999	6.45	5.98	97.12 ± 6.26	96.16 ± 5.76
2-MF	0.090	0.270	≥0.9999	5.88	5.29	97.34 ± 4.72	98.70 ± 5.76
3-MF	0.093	0.280	≥0.9999	4.84	5.84	97.34 ± 4.72	98.70 ± 5.76
2-EF	0.019	0.056	≥0.9999	5.32	5.35	95.84 ± 5.10	97.61 ± 5.22
2,5-DMF	0.074	0.223	≥0.9999	4.49	4.78	94.61 ± 4.25	98.57 ± 4.70
3-FA	1.47	4.41	≥0.9995	3.21	2.95	97.99 ± 3.15	99.31 ± 2.92
2-FA	1.77	5.30	≥0.9999	6.70	2.23	92.76 ± 6.22	99.98 ± 2.23
2-FOL	88.0	264	≥0.9990	3.04	3.73	96.79 ± 2.95	101.16 ± 3.77
3-FOL	108	325	≥0.9992	1.48	5.28	93.34 ± 1.49	101.00 ± 5.33
2-AF	0.40	1.20	≥0.9991	3.05	2.76	94.24 ± 3.21	102.56 ± 2.83
2-PF	0.030	0.090	≥0.9997	8.06	6.16	108.72 ± 8.76	94.94 ± 5.85

Table 2. Limits of detection (LOD), limits of quantification (LOQ), linearity, repeatability, and reproducibility for furan, 2-methylfuran (2-MF), 3-methylfuran (3-MF), 2-ethylfuran (2-EF), 2,5-dimethylfuran (2,5-DMF), 3-furaldehyde (3-FA), furfural (2-FA), furfuryl alcohol (2-FOL), 3-furanmethanol (3-FOL), 2-acetylfuran (2-AF), and 2-pentylfuran (2-PF)

Compound

LOD^a [ng]

LOQ^b [ng]

R^2c

RSD low conc. [%]^d

RSD high conc. [%]^e

Accuracy low conc. [%]^f

Accuracy high conc. [%]^g

^aLimit of detection (LOD) based on signal-to-noise (S/N) of ≥3; ^bLimit of quantification (LOQ) based on S/N of ≥10; ^cLinearity expressed by correlation coefficient (R²) (n = 3); ^dPrecision at low concentration levels (spiked with 10 µL of standard solution) expressed by relative standard deviation (RSD) (n = 6); ^ePrecision at high concentration levels (spiked with 500 µL of standard solution) expressed by RSD (n = 6); ^fAccuracy at low concentration levels (spiked with 10 µL of standard solution) expressed by the coefficient of determined amount and spiked amount × 100 (n = 6); ^gAccuracy at high concentration levels (spiked with 500 µL of standard solution) expressed by coefficient of determined amount and spiked amount × 100 (n = 6).

Furan

0.323

0.970

≥0.9999

6.45

5.98

97.12 ± 6.26

96.16 ± 5.76

2-MF

0.090

0.270

≥0.9999

5.88

5.29

97.34 ± 4.72

98.70 ± 5.76

3-MF

0.093

0.280

≥0.9999

4.84

5.84

97.34 ± 4.72

98.70 ± 5.76

2-EF

0.019

0.056

≥0.9999

5.32

5.35

95.84 ± 5.10

97.61 ± 5.22

2,5-DMF

0.074

0.223

≥0.9999

4.49

4.78

94.61 ± 4.25

98.57 ± 4.70

3-FA

1.47

4.41

≥0.9995

3.21

2.95

97.99 ± 3.15

99.31 ± 2.92

2-FA

1.77

5.30

≥0.9999

6.70

2.23

92.76 ± 6.22

99.98 ± 2.23

2-FOL

88.0

264

≥0.9990

3.04

3.73

96.79 ± 2.95

101.16 ± 3.77

3-FOL

108

325

≥0.9992

1.48

5.28

93.34 ± 1.49

101.00 ± 5.33

2-AF

0.40

1.20

≥0.9991

3.05

2.76

94.24 ± 3.21

102.56 ± 2.83

2-PF

0.030

0.090

≥0.9997

8.06

6.16

108.72 ± 8.76

94.94 ± 5.85

**Table 3.** Contents [mg/100 g sample] of furan, 2-methylfuran (2-MF), 3-methylfuran (3-MF), 2-ethylfuran (2-EF), furfural (2-FA), and 2-pentylfuran (2-PF) (mean ± SD, n = 3) obtained by heat treatment of different oils in model A at pH 7 and the corresponding fatty acid composition concerning the polyunsaturated fatty acids α-linolenic acid (ALA), docosahexaenoic acid (DHA), docosapentaenoic acid (DPA), eicosapentaenoic acid (EPA), and linoleic acid (LA)
	Contents of furanoic compounds [mg/100 g sample]	Data from literature
^aSpecification of distributor; ^bnd = not detected (< limit of detection). Noticeable data in italic.
Linseed oil (Firestone, 2013)	112.56 ± 11.76	5.80 ± 0.54	0.20 ± 0.02	216.32 ± 26.93	3.90 ± 0.34	37.94 ± 5.01	35–66	7–25	–
Algea oil (74% algea oil, 23% olive oil, 2% sunflower oil)^a	58.76 ± 3.19	5.89 ± 0.20	0.83 ± 0.04	72.75 ± 3.88	4.72 ± 0.52	6.83 ± 1.10	no specification	EPA: 609; DPA: 157; DHA: 1,158
Fish oil (80% fish oil, 19% olive oil)^a	35.78 ± 10.14	4.22 ± 0.62	0.63 ± 0.06	50.84 ± 14.69	2.19 ± 0.50	5.24 ± 1.87	no specification	EPA: 560; DPA: 64; DHA: 268
Soybean oil (Firestone, 2013)	4.02 ± 0.57	1.36 ± 0.08	0.28 ± 0.02	2.24 ± 0.31	0.27 ± 0.04	12.52 ± 2.26	5.5–11.0	46.2–57.1	–
Safflower oil (Firestone, 2013)	20.73 ± 1.88	1.11 ± 0.15	0.22 ± 0.03	1.16 ± 0.06	1.62 ± 0.24	75.34 ± 0.70	0–0.13	8.7–83.2	–
Rapeseed oil (Firestone, 2013)	0.88 ± 0.04	0.78 ± 0.08	0.16 ± 0.02	0.62 ± 0.01	0.11 ± 0.01	nd^b	4–25	10–40	–
Olive oil (Firestone, 2013)	1.19 ± 0.15	1.51 ± 0.26	0.32 ± 0.06	0.53 ± 0.08	0.19 ± 0.04	nd	0–4	3.5–21.0	–
Sunflower oil (Firestone, 2013)	26.66 ± 9.36	nd	nd	nd	1.65 ± 0.62	97.10 ± 22.64	0–0.5	17–85	–
Coconut oil (Firestone, 2013)	nd	nd	nd	nd	nd	nd	0–0.2	0.8–2.1	–

Table 3. Contents [mg/100 g sample] of furan, 2-methylfuran (2-MF), 3-methylfuran (3-MF), 2-ethylfuran (2-EF), furfural (2-FA), and 2-pentylfuran (2-PF) (mean ± SD, n = 3) obtained by heat treatment of different oils in model A at pH 7 and the corresponding fatty acid composition concerning the polyunsaturated fatty acids α-linolenic acid (ALA), docosahexaenoic acid (DHA), docosapentaenoic acid (DPA), eicosapentaenoic acid (EPA), and linoleic acid (LA)

Contents of furanoic compounds [mg/100 g sample]

Data from literature

Furan

2-MF

3-MF

2-EF

2-FA

2-PF

ALA [%]

LA [%]

DHA/EPA/DPA [mg/100 mL]

^aSpecification of distributor; ^bnd = not detected (< limit of detection). Noticeable data in italic.

Linseed oil (Firestone, 2013)

112.56 ± 11.76

5.80 ± 0.54

0.20 ± 0.02

216.32 ± 26.93

3.90 ± 0.34

37.94 ± 5.01

35–66

7–25

–

Algea oil (74% algea oil, 23% olive oil, 2% sunflower oil)^a

58.76 ± 3.19

5.89 ± 0.20

0.83 ± 0.04

72.75 ± 3.88

4.72 ± 0.52

6.83 ± 1.10

no specification

EPA: 609; DPA: 157; DHA: 1,158

Fish oil (80% fish oil, 19% olive oil)^a

35.78 ± 10.14

4.22 ± 0.62

0.63 ± 0.06

50.84 ± 14.69

2.19 ± 0.50

5.24 ± 1.87

no specification

EPA: 560; DPA: 64; DHA: 268

Soybean oil (Firestone, 2013)

4.02 ± 0.57

1.36 ± 0.08

0.28 ± 0.02

2.24 ± 0.31

0.27 ± 0.04

12.52 ± 2.26

5.5–11.0

46.2–57.1

–

Safflower oil (Firestone, 2013)

20.73 ± 1.88

1.11 ± 0.15

0.22 ± 0.03

1.16 ± 0.06

1.62 ± 0.24

75.34 ± 0.70

0–0.13

8.7–83.2

–

Rapeseed oil (Firestone, 2013)

0.88 ± 0.04

0.78 ± 0.08

0.16 ± 0.02

0.62 ± 0.01

0.11 ± 0.01

nd^b

4–25

10–40

–

Olive oil (Firestone, 2013)

1.19 ± 0.15

1.51 ± 0.26

0.32 ± 0.06

0.53 ± 0.08

0.19 ± 0.04

0–4

3.5–21.0

–

Sunflower oil (Firestone, 2013)

26.66 ± 9.36

1.65 ± 0.62

97.10 ± 22.64

0–0.5

17–85

–

Coconut oil (Firestone, 2013)

0–0.2

0.8–2.1

–