J Food Bioact

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

Journal website www.isnff-jfb.com

Original Research

Volume 8, December 2019, pages 51-57

Differentiation between aroma-related bioactives in native cold-pressed rapeseed oils with desired sensory attributes and with a fusty/musty off-flavor using multivariate methods

Figure 1. Heatmap, illustrating the clustering of oil samples with desired sensory attributes (PC and PC1-5) or a fusty/musty off-flavor (OF and OF1-8) as well as two corresponding rapeseed samples (OFS and OFS8), from which OF and OF8 were pressed. Concentrations (µg/kg) are displayed in colors with the lowest in white and the highest in red.

Figure 2. Scoreplot of the PCA, showing a clear discrimination of the group of oil samples with desired sensory attributes (PC and PC1-5) from the group of fusty/musty off-flavor oil samples (OF and OF1-8) as well as two corresponding rapeseed samples (OFS and OFS8), from which OF and OF8 were pressed.

Figure 3. Biplot of the PCA, showing a clear discrimination of the group of oil samples with desired sensory attributes (PC and PC1-5) from the group of fusty/musty off-flavor oil samples (OF and OF1-8) as well as two corresponding rapeseed samples (OFS and OFS8), from which OF and OF8 were pressed. Compounds responsible for the successful discrimination are displayed.

**Table 1.** Concentrations of 17 selected odorants in the positive control (PC) and further five native cold-pressed rapeseed oils eliciting the desired sensory attributes (PC1-PC5)
No.	Compound	Concentrations^a (µg/kg)
^aMean values of triplicates, differing not more than 15%.
1	2-methylbutanoic acid	0.03	48.7	18.0	17.1	42.8	51.1
2	3-methylbutanoic acid	25.1	43.2	38.5	15.6	37.2	97.8
3	4-methylphenol	0.54	1.09	1.20	1.08	1.15	1.36
4	2-sec-butyl-3-methoxypyrazine	1.54	1.60	1.23	0.82	1.20	3.34
5	2-ethyl-3,6-dimethylpyrazine	0.28	0.27	0.44	0.22	0.43	0.12
6	3-hydroxy-4,5-dimethylfuran-2(5H)-one	0.46	0.13	0.12	0.27	0.19	0.23
7	ethyl 2-methylbutanoate	0.14	0.35	0.19	0.12	0.44	0.35
8	2-methoxyphenol	0.18	0.20	0.33	0.28	0.43	0.20
9	2-phenylethanol	24.2	45.1	44.8	29.7	55.6	95.3
10	2-ethyl-3,5-dimethylpyrazine	0.07	0.01	0.04	0.04	0.03	0.01
11	2-isobutyl-3-methoxypyrazine	0.18	1.58	1.11	0.12	1.63	1.80
12	2-methylbutanal	16.9	2.85	5.69	3.93	9.00	12.4
13	3-methylbutanal	32.8	8.66	11.7	6.31	13.4	25.8
14	dimethyl trisulfide	1.10	0.72	0.58	0.83	1.20	0.38
15	acetylpyrazine	0.04	0.01	0.01	0.01	0.02	0.02
16	2-acetylpyridine	0.40	0.10	0.21	0.12	0.17	0.18
17	2-isopropyl-3-methoxyprazine	3.29	0.96	0.50	0.42	0.48	1.24

Table 1. Concentrations of 17 selected odorants in the positive control (PC) and further five native cold-pressed rapeseed oils eliciting the desired sensory attributes (PC1-PC5)

No.

Compound

Concentrations^a (µg/kg)

PC1

PC 2

PC 3

PC 4

PC 5

^aMean values of triplicates, differing not more than 15%.

2-methylbutanoic acid

0.03

48.7

18.0

17.1

42.8

51.1

3-methylbutanoic acid

25.1

43.2

38.5

15.6

37.2

97.8

4-methylphenol

0.54

1.09

1.20

1.08

1.15

1.36

2-sec-butyl-3-methoxypyrazine

1.54

1.60

1.23

0.82

1.20

3.34

2-ethyl-3,6-dimethylpyrazine

0.28

0.27

0.44

0.22

0.43

0.12

3-hydroxy-4,5-dimethylfuran-2(5H)-one

0.46

0.13

0.12

0.27

0.19

0.23

ethyl 2-methylbutanoate

0.14

0.35

0.19

0.12

0.44

0.35

2-methoxyphenol

0.18

0.20

0.33

0.28

0.43

0.20

2-phenylethanol

24.2

45.1

44.8

29.7

55.6

95.3

2-ethyl-3,5-dimethylpyrazine

0.07

0.01

0.04

0.03

0.01

2-isobutyl-3-methoxypyrazine

0.18

1.58

1.11

0.12

1.63

1.80

2-methylbutanal

16.9

2.85

5.69

3.93

9.00

12.4

3-methylbutanal

32.8

8.66

11.7

6.31

13.4

25.8

dimethyl trisulfide

1.10

0.72

0.58

0.83

1.20

0.38

acetylpyrazine

0.04

0.01

0.02

2-acetylpyridine

0.40

0.10

0.21

0.12

0.17

0.18

2-isopropyl-3-methoxyprazine

3.29

0.96

0.50

0.42

0.48

1.24

**Table 2.** Concentrations of 17 selected odorants in the positive control (PC), off-flavor oil (OF), further seven native cold-pressed rapeseed oils eliciting a fusty/musty off-flavor (OF1-OF7), and rapeseed sample, from which OF8 was pressed (OFS8)
No.	Compound	Concentrations^a (µg/kg)
^aMean values of triplicates, differing not more than 15%.
1	2-methylbutanoic acid	0.03	344	120	255	241	216	211	161	302	80.4	78.3
2	3-methylbutanoic acid	25.1	472	508	778	773	706	695	575	908	152	255
3	4-methylphenol	0.54	5.82	10.8	39.5	28.0	28.6	33.1	24.2	33.3	2.39	2.43
4	2-sec-butyl-3-methoxypyrazine	1.54	8.56	4.01	3.89	3.98	3.37	3.43	3.42	3.52	1.89	3.45
5	2-ethyl-3,6-dimethylpyrazine	0.28	10.1	2.16	8.72	9.72	7.86	12.5	12.0	9.72	8.26	19.5
6	3-hydroxy-4,5-dimethylfuran-2(5H)-one	0.46	13.4	1.76	1.16	1.85	1.41	1.63	1.42	1.18	0.46	1.77
7	ethyl 2-methylbutanoate	0.14	59.9	1.61	10.3	11.1	11.6	8.56	19.3	19.3	31.2	51.8
8	2-methoxyphenol	0.18	140	1.20	1.55	1.51	1.38	1.47	1.95	2.00	2.33	2.92
9	2-phenylethanol	24.2	210	140	140	213	221	212	240	289	167	175
10	2-ethyl-3,5-dimethylpyrazine	0.07	2.64	0.47	0.39	0.43	0.29	0.38	0.54	1.67	0.86	1.48
11	2-isobutyl-3-methoxypyrazine	0.18	3.67	0.39	0.57	0.57	0.56	0.52	0.55	0.59	1.26	3.45
12	2-methylbutanal	16.9	336	13.1	50.1	46.3	38.3	60.9	35.1	104	57.1	38.3
13	3-methylbutanal	32.8	177	6.47	34.8	22.7	13.7	21.8	18.0	41.1	135	67.3
14	dimethyl trisulfide	1.10	89.6	0.54	2.16	1.63	1.83	1.41	0.62	0.47	8.95	19.9
15	acetylpyrazine	0.04	0.84	0.02	0.07	0.06	0.07	0.10	0.08	0.07	0.50	0.44
16	2-acetylpyridine	0.40	14.2	0.18	0.25	3.57	2.57	0.30	0.32	0.28	3.30	3.45
17	2-isopropyl-3-methoxypyrazine	3.29	2.94	1.18	2.46	2.99	2.19	1.83	3.22	2.02	0.63	1.29

Table 2. Concentrations of 17 selected odorants in the positive control (PC), off-flavor oil (OF), further seven native cold-pressed rapeseed oils eliciting a fusty/musty off-flavor (OF1-OF7), and rapeseed sample, from which OF8 was pressed (OFS8)

No.

Compound

Concentrations^a (µg/kg)

OF 1

OF 2

OF 3

OF 4

OF 5

OF 6

OF 7

OF 8

OFS8

^aMean values of triplicates, differing not more than 15%.

2-methylbutanoic acid

0.03

344

120

255

241

216

211

161

302

80.4

78.3

3-methylbutanoic acid

25.1

472

508

778

773

706

695

575

908

152

255

4-methylphenol

0.54

5.82

10.8

39.5

28.0

28.6

33.1

24.2

33.3

2.39

2.43

2-sec-butyl-3-methoxypyrazine

1.54

8.56

4.01

3.89

3.98

3.37

3.43

3.42

3.52

1.89

3.45

2-ethyl-3,6-dimethylpyrazine

0.28

10.1

2.16

8.72

9.72

7.86

12.5

12.0

9.72

8.26

19.5

3-hydroxy-4,5-dimethylfuran-2(5H)-one

0.46

13.4

1.76

1.16

1.85

1.41

1.63

1.42

1.18

0.46

1.77

ethyl 2-methylbutanoate

0.14

59.9

1.61

10.3

11.1

11.6

8.56

19.3

31.2

51.8

2-methoxyphenol

0.18

140

1.20

1.55

1.51

1.38

1.47

1.95

2.00

2.33

2.92

2-phenylethanol

24.2

210

140

213

221

212

240

289

167

175

2-ethyl-3,5-dimethylpyrazine

0.07

2.64

0.47

0.39

0.43

0.29

0.38

0.54

1.67

0.86

1.48

2-isobutyl-3-methoxypyrazine

0.18

3.67

0.39

0.57

0.56

0.52

0.55

0.59

1.26

3.45

2-methylbutanal

16.9

336

13.1

50.1

46.3

38.3

60.9

35.1

104

57.1

38.3

3-methylbutanal

32.8

177

6.47

34.8

22.7

13.7

21.8

18.0

41.1

135

67.3

dimethyl trisulfide

1.10

89.6

0.54

2.16

1.63

1.83

1.41

0.62

0.47

8.95

19.9

acetylpyrazine

0.04

0.84

0.02

0.07

0.06

0.07

0.10

0.08

0.07

0.50

0.44

2-acetylpyridine

0.40

14.2

0.18

0.25

3.57

2.57

0.30

0.32

0.28

3.30

3.45

2-isopropyl-3-methoxypyrazine

3.29

2.94

1.18

2.46

2.99

2.19

1.83

3.22

2.02

0.63

1.29