Characterization and Comparison of Unfermented and Fermented Seed-Watermelon Juice

Table 3

Volatiles of the unfermented and fermented juice.

Type	Assigned compounds	Aroma	Classification	Unfermented juice (mg/L)	Fermented juice (mg/L)
Esters	Ethyl acetate	Bouquet with a light fruit smell	Fruit, fragrant, bouquet	—	21.3 ± 1.58
	Isoamyl acetate	Banana-like aroma	Fruit	—	13.0 ± 0.67
	Ethyl octanoate	Brandy aroma with sweet smell	Bouquet, fragrant	—	30.5 ± 2.32
	Heptyl formate	Fruit and flower smell	Fruit, flower, oil	—	11.0 ± 1.02
	Ethyl nonanoate	Fruit and brandy-like aroma	Oil, fruit, bouquet	—	2.42 ± 0.36
	2-Methylpropyl octanoate	—	—	—	0.91 ± 0.05
	Ethyl decanoate	Coconut aroma	Fruit	—	65.8 ± 2.81
	Ethyl undecanoate	Bouquet, oil, fruit	Bouquet, oil, fruit	—	1.23 ± 0.24
	Phenethyl acetate	Sweet aroma	Fragment	—	1.01 ± 0.2
	Ethyl laurate	Fragment and fruit	Fragment, fruit	—	35.4 ± 1.55
	3-Methylbutyl decanoate	—	—	—	5.46 ± 0.84
	Ethyl myristate	Coconut and iris-like aroma, sweetness	Fruit, fragment	—	11.7 ± 0.87
	Ethyl pentadecanoate	—	—	—	0.61 ± 0.05
	Ethyl palmitoleate	Fruit and cream aroma	Fruit, oil	—	4.34 ± 1.21
		Subtotal		0	174.18
Alcohols	Isobutanol	Grape wine smell	Bouquet	—	2.73 ± 0.24
	Isoamylol	Calvados aroma and spicy	Bouquet	8.27 ± 1.25	17.3 ± 1.10
	Hexanol	Grass, fragment, fruit, and oil	Grass, fragment, fruit, oil	74.2 ± 7.64	22.1 ± 0.87
	2,3-Butanediol	—	—	—	1.07 ± 0.09
	Octanol	Fruit, flower, and grass	Fruit, flower, grass	8.06 ± 1.55	11.9 ± 1.17
	1-Methoxy-2-butanol	—	—	—	0.91 ± 0.04
	1-Nonanol	Watermelon-like aroma	Flower, fruit	24.13 ± 2.31	14.8 ± 0.87
	3,6-Nonadien-1-ol	Watermelon-like aroma	Fruit	14.65 ± 1.02	11.0 ± 1.24
	Phenylethanol	Pleasant and lasting fragrance of roses	Flower	—	40.3 ± 2.91
	Tridecanol	—	—	4.32 ± 0.32	3.54 ± 0.23
	Alaninol	—	—	3.37 ± 0.48	—
	3-Hexen-1-ol	Strong smell of grass and fresh tea	Grass	14.4 ± 1.24	—
	trans-2-Hexen-1-ol	Fruit and grass	Fruit, grass	1.54 ± 0.09	—
	1-Octen-3-ol	Mushroom and mud-like aroma	Grass	5.71 ± 1.02	—
	Heptanol	Citrus aroma	Fruit, oil	6.53 ± 1.45	—
	2-Ethylhexan-1-ol	Sweet and light fragrance	Flower	8.44 ± 2.52	—
	Benzyl alcohol	Light flower aroma	Flower	1.75 ± 0.07	—
	Nerolidol	—	—	2.17 ± 0.73	—
		Subtotal		177.54	125.65
Alkanes	4-Vinyl-2-methoxyphenol	Flower, bouquet, and fruit	Flower, bouquet, fruit	—	0.41 ± 0.02
	1,3-Di-tert-butylbenzene	—	—	18.4 ± 1.62	—
	Tridec-1-yne	—	—	2.86 ± 0.21	—
	β-Caryophyllene	Light clove fragrance	Flower	5.37 ± 1.24	224 ± 10.8
	Valencene	Citrus aroma	Fruit	5.77 ± 0.88	—
	2,4-Di-tert-butylphenol	—	—	6.87 ± 0.79	—
		Subtotal		39.27	224.41
Aldehyde and ketones	Nonanal	Watermelon aroma, sweet with beeswax flower	Fruit, flower	12.9 ± 1.25	0.61 ± 0.02
	trans-2-Nonenal	Watermelon and cucumber-like aroma	Fruit	16.8 ± 2.06	—
	trans,cis-2-6-Nonadienal	Watermelon-like aroma	Fruit	23.6 ± 2.18	—
	β-Cyclocitral	Fruit and flower	Fruit, flower	8.38 ± 1.38	—
	β-Jonone	Violet aroma	Flower	2.96 ± 0.63	—
	3-Hydroxy-2-oxobutane	Cream aroma	Oil	6.09 ± 1.24	—
		Subtotal		70.73	0.61
Acids	Acetic acid	—	—	—	6.72 ± 1.54
	Octanoate	Fruit	Fruit	2.38 ± 0.35	5.36 ± 2.08
	Decanoic acid	—	—	—	7.14 ± 0.96
		Subtotal		2.38	19.22

—, not detected or not found; a significant difference with data in the same line.