Table 1.

Compounds involved in secondary aroma, classes of volatile aroma, main representative, desirable concentration, sensorial properties and producer microorganisms.

Aromatic Class	Main Compounds	Desirable Concentration	Sensorial Properties	Producer Organism	Ref.
Fatty acids	Acetic acid, pentanoic acid, hexanoic acid, octanoic acid, decanoic acid, 9-Decenoic acid, 3-methylbutanoic acid, sobutyric acid	200–700 mg/L	In excessive amount: rancid, greasy, and cheesy notes	S. cerevisiae, P. fermentas, C. zemplinina, H. guilliermondii, H. vineae, H. uvarum	[3,19,31]
Higher alcohols	1-Propanol-isobutanol, isoamyl alcohol, 2-Phenylethanol, tyrosol, tryptophol, 2-methylbutanol-1, 3-methyl-1-butanol-1	<300 mg/L	Floral, honey, and fruity notes (<300 mg/L). Pungent aroma (>400 mg/L)	S. cerevisiae, C. zemplinin, H. uvarum, H. osmophila, H. guilliermondii, P. anomala, P. membranifaciens	[2,3,5,8,19]
Esters	Ethyl hexanoate, ethyl octanoate, ethyl decanoate, ethyl acetate, isobutyl acetate, amyl acetate, hexyl acetate, 2PA, isoamyl acetate	150–200 mg/L	Fruity aroma, including banana or apple, honey, and floral tones	S. cerevisiae, Candida, Hansenula, Pichia	[2,3,7,19]
Phenolics	4-Vinyl guajacol, 4-Vinylphenol	-	Sweet vanillin aroma	LAB	[1,7,31]