Table 2 Identified volatile compounds in unfermented and fermented plant-based milks, aroma attributes, odour groups, and the odour threshold in air

Aldehydes

 1

3-Methyl-butanal

Malty, fatty, cocoa, fruity

1

11

MS, RI

 2

2-Methyl-butanal

Malty, cocoa

1

11

MS, RI

 3

Hexanal

Green, grassy, nutty, fat, oxidized oil

6

0.28

MS, STD, RI

 4

2,4-Heptadienal³

Fatty, creamy, green

3

8

MS, RI

 5

2-Heptenal

Green, fatty

6

19

MS, RI

 6

Heptanal

Green, citrus, fatty, floral, rancid

6

0.18

MS, STD, RI

 7

Benzaldehyde

Sweet, fruity, almond

1

20

MS, STD, RI

 8

2-Octenal

Fatty

3

0.53

MS, RI

 9

Phenylacetaldehyde

Floral, sweet, honey

2

4

MS, STD, RI

 10

4-Ethyl-benzaldehyde

Fruity

1

13

MS, RI

 11

2-Nonenal

Green, musty, fatty,

6

0.02

MS, RI

 12

Nonanal

Citrus, floral, fatty, green, smoky

1

0.34

MS, STD, RI

 13

2,4-Decadienal⁴

Grass, fatty, melon, aldehyde

6

0.07

MS, RI

 14

Decanal

Fatty, floral

3

0.10

MS, RI

Alcohols

 1

[S, S]-2,3-Butanediol^1,2

Creamy, buttery

3

49

MS, RI

 2

3-Methyl-2-buten-1-ol ²

Fruity

1

173

MS, RI

 3

3-Methyl-1-butanol ^2,4

Fruity, banana, whiskey, floral, fermented

1

68

MS, RI

 4

2-Methyl-1-butanol ^1,4

Ethereal, floral

1

68

MS, RI

 5

1-Pentanol

Fermented, sweet, fruity, balsamic, alcoholic

1

43

MS, STD, RI

 6

1-Hexanol

Fruity, lemon

1

6

MS, STD, RI

 7

2-Heptanol^1,3,4

Citrus, fruity, herbal

1

41

MS, RI

 8

1-Heptanol

Light green, mushroom, rancid

6

3

MS, STD, RI

 9

Benzyl alcohol^2,3

Floral

2

1 × 10⁴

MS, RI

 10

2-Methyl-3-hexanol¹

Unknown

9

MS, RI

 11

Phenylethyl alcohol^2,4

Floral, rose, honey

2

0.02

MS, STD, RI

 12

1-Octen-3-ol

Earthy, mushroom

7

0.52

MS, RI

 13

2-Octen-1-ol^1,2,3,4

Cucumber

2

40

MS, RI

 14

3-Octanol⁴

Earthy

7

27

MS, RI

 15

2-Ethyl-1-hexanol⁴

Citrus, floral

1

130

MS, RI

 16

1-Octanol

Waxy, aldehyde, fruity, floral

3

2.7

MS, RI

 17

1-Nonanol^2,4

Citrus, rose

1

0.9

MS, RI

 18

Eugenol⁴

Pleasant spicy, clove-like

2

6

MS, STD, RI

 19

Cherry-propanol

Fruity

1

MS, RI

 20

Trans-pinocarveol

Woody, balsamic

5

MS, RI

 21

cis-Verbenol

Balsamic, pine

5

MS, RI

 22

(-)-Myrtenol

Woody, minty, camphoraceous

5

0.32

MS, RI

 23

Myrtenol

Woody, herbal, floral

5

0.32

MS, RI

 24

Linalool

Floral, fruity

2

4

MS, RI

 25

Terpinen-4-ol

Balsamic, woody, green, fatty, fruity, floral, spicy

5

150

MS, RI

 26

3-Ethyl-4-nonanol^2,3

Unknown

9

MS, RI

Ketones

 1

Methyl-vinyl-ketone

Pungent, sweet

8

MS

 2

2,3-Butanedione^2,3,4

Buttery, sweet, creamy

3

0.3

MS, RI

 3

3-Hydroxybutan-2-one^2,4

Buttery, creamy, sweet, toasted

3

0.3

MS, RI

 4

2,3-Pentanedione³

Buttery, sweet

3

12

MS, RI

 5

2-Hexanone^{1, 2}

Fruity

1

24

MS, RI

 6

2,3-Heptanedione¹

Buttery

3

MS, RI

 7

3,6-Heptanedione²

Buttery

3

MS, RI

 8

2-Heptanone

Fruity, floral, sweet, cheesy

1

0.76

MS, RI

 9

1-(2-Furanyl)-1-propanone²

Fruity

1

MS, RI

 10

3,5-Octadien-2-one

Fruity, fatty, green, earthy

1

5

MS, RI

 11

6-Methyl-5-hepten-2-one³

Citrus, musty, green

1

1

MS, RI

 12

5-Methyl-3-hepten-2-one

Unknown

9

MS, RI

 13

3-Octanone⁴

Earthy [1], mushroom-like [3], fresh [3], herbal [3], ripe banana [3]

7

21

MS, RI

 14

Isoacetovanillone

Unknown

9

MS, RI

 15

2-Nonanone⁴

Sweet, fruity, floral, green, hot milk, soap

1

5

MS, RI

 16

5,6-Dehydrocamphor

Unknown

9

MS, RI

 17

Pinocarvone

Camphoraceous, fresh

5

MS, RI

 18

D-Verbenone

Camphoraceous, minty, spicy

5

MS, RI

Organic acids

 1

Acetic acid^1,2,3,4

Acidic, sour, vinegar

4

6

MS, STD, RI

 2

3-Methyl-butanoic acid^1,3

Cheesy

4

0.08

MS, RI

 3

2-Methyl-butanoic acid^2,3

Sour, cheesy, fermented

4

0.04

MS, RI

 4

Pentanoic acid¹

Cheesy, acidic, unpleasant

4

8.90

MS, RI

 5

Hexanoic acid^2,3

Cheesy, fatty, sour, sharp, rancid

4

0.60

MS, RI

 6

Octanoic acid^2,3

Cheesy, fatty, sweaty

4

27

MS, RI

 7

Nonanoic acid

Waxy, earthy

3

1.9

MS, RI

Esters

 1

Ethylacetate

Sweet, fruity, mild

1

870

MS, RI

 2

Ethyllactate¹

Fruity, buttery

1

5 × 10⁴

MS, RI

 3

Ethyl 2-methylbutyrate

Fruity

1

0.01

MS, RI

 4

Hexyl acetate

Fruity, sweet

1

1.8

MS, RI

 5

Verbenylacetate

Unknown

9

MS, RI

 6

Bornyl acetate²

Balsamic, camphoraceous

5

75

MS

 7

Epoxy-alpha-terpenylacetate

Unknown

9

MS, RI

 Furans

 1

2-Ethyl-furan³

Chemical, sweet, coffee-like

8

1.3 × 10⁶

MS, RI

 2

2-Ethyl-5-methylfuran²

Grassy

8

MS, RI

 3

2-Acetyl-5-methylfuran

Nutty

5

MS, RI

 4

2-n-Butyl furan¹

Spicy, fruity, wine-like

8

1 × 10⁵

MS, RI

 5

2-(1-Pentenyl)-furan³

Roasted

5

MS, RI

6

2-Pentyl-furan

Beany, green, grassy, nutty, fatty

6

3.4

MS, RI

 7

2-n-Heptylfuran

Green, fatty

6

MS, RI

Alkanes

 1

Undecane

Unknown

9

620

MS, STD, RI

 2

Dodecane

Unknown

9

110

MS, STD, RI

 3

Tridecane

Unknown

9

MS, STD, RI

Alkenes

 1

α -Pinene

Pine, woody, herbal, fresh, fruity

5

18

MS, STD, RI

 2

Camphene

Woody, herbal, camphoraceous

5

130

MS, RI

 3

β-Terpinene

Terpenic, fatty

5

130

MS, RI

 4

3-Carene

Citrus, sweet

1

140

MS, RI

 5

p-Cymene

Fruity, fresh, citrus, terpenic, floral, fragrant

1

57

MS, RI

 6

D-Limonene

Citrus, fresh, sweet

1

38

MS, STD, RI

 7

γ-Terpinene

Terpenic, citrus, herbal

5

5 × 10⁴

MS, RI

 8

α-Thujene²

Woody, herbal, green

5

MS, RI

 9

Alloocimene¹

Floral, sweet, nut

2

1.8 × 10⁴

MS, RI

 10

β-Thujene

Unknown

MS, RI

 11

2,4-Dimethyl-1-decene

Unknown

9

MS, RI

 12

β-Gurjunene

Unknown

9

MS, RI

Others

 1

Dimethyl ether^2,3,4

Ethereal

1

5 × 10⁵

MS, RI

 2

4-Ethenyl-1,2-dimethyl-benzene

Unknown

9

MS, RI

 3

4-Methyl-2-propylphenol¹

Unknown

9

MS, RI

 4

α-Limonene-di-epoxide

Citrus

1

MS, RI

 5

Unknown³

 6

Unknown

 7

Unknown⁴

 8

Unknown

 9

Unknown

 10

Unknown

 11

Unknown

 12

Unknown