Table 2.

Different patterns found among several gluten-free breads (quinoa, teff, rice and wheat flours and corn and wheat starches) and wheat control bread in the release of volatile compounds to the oven (headspace) measured by PTR-ToF-MS during 40 min. of baking at 200 °C.

Origin Based on the PTR-ToF-MS Pattern of Release of Volatile Compounds to the Oven during Baking	Possible Volatile Compounds
Fermentation origin	3-methyl-1-butanol, 2-methyl-1-butanol, 1-pentanol, 2,3-butanedione, 3-methylbutanal, 2-methylbutanal, acetaldehyde, ethanol
Lipids oxidation origin	1-hexanol, hexanal, heptanal, 1-octen-3-ol, nonanal, 2,4-decadienal, 3-penten-2-ol
Esters origin	ethyl octanoate, ethyl hexanoate and hexyl acetate
Acids origin	hexanoic acid
Fermentation-Maillard high retention in bread origin	phenylethyl alcohol, phenylacetaldehyde, benzaldehyde, benzyl alcohol, 3-methyl-butanoic acid and 2-methyl-butanoic acid
Fermentation-Maillard low retention in bread origin	acetic acid, butanoic acid and acetoin
Early Maillard origin	1-methyl-pyrrol, limonene, 2,3-diethyl-5-methylpyrazine, 2-ethyl-3-methylpyrazine, 2-acetylpyrazine, 2,3-diethylpyrazine, 2,5-diethylpyrazine, 2,6-diethylpyrazine, 3-ethyl-2,5-dimethylpyrazine, 2-ethyl-3,5-dimethylpyrazine, 5-ethyl-2,3-dimethylpyrazine, 3-ethyl-2,6-dimethylpyrazine and 2-ethyl-3,6-dimethylpyrazine
Late Maillard origin	2-acetyl-1-pyrroline, 2-ethylpyrazine, 2,3-dimethylpyrazine, 2,5-dimethylpyrazine and 2,6-dimethylpyrazine
Caramelization-Maillard origin	furan, furfuryl alcohol, furfural, 5-methyl-2(5H)-furanone, 5-methyl-furfural, 2-methylfuran