Table 3.

Volatile compounds identified in pineapple breads (conventionally processed, CPb; fully frozen, Fpb and partially baked, Ppb).

Number	Odourant a	Odour quality b	FD	Retention index DB-5	Previously identified in bread c
1	Ethyl acetate	Pineapple-like	32	628	2, 4
2	Propanoic acid	Rancid	32	668	4, 7
3	Methyl-2-methylpropionate	Fruity, sweet	4	687	9
4	2,3-Pentanedione	Buttery	16	710	1, 4, 5 & 10
5	Ethyl propionate	Fruity	64	713
6	Butanoic acid	sour	2	718	4, 5
7	3-Hydroxy-2-butanone	Buttery	64	720	2, 3
8	Ethyl-2-methyl propionate	Sweet-fruity	4	754	4, 6, 9
9	2-/3Methyl-1-butanol	Malty	128	769	2, 3, 4
10	1-Hexen-3-one	Green	2	774	1, 4, 10
11	Hexanal	Green, tallow	32	787	1,2, 3, 7
12	2,3-Butanediol	Fruity, onion	8	802	1, 2
13	Furfural	Bread-like	64	826	1, 2, 3
14	2-Methyl butanoic acid	Sweaty	16	831	1, 4
15	Ethyl-2-methyl butanoate	Fruity	8	838	9
16	Furfuryl alcohol	Burnt	16	863
17	Methyl ethanoate	Fruity	32	864	4
18	(Z)-4-Heptenal	Biscuit-like, sweet	16	894	1, 4, 5, 6, 7, 10
19	Methional	cooked-potato	4	919	4, 5, 6, 7, 10
20	2-Acetyl-1-pyrroline d	Popcorn-like	16	922	4, 5, 6, 10
21	Benzaldehyde	Almond-like	64	936	4,7
22	Ethanol	Alcoholic	32	945	3, 6,
23	Hexanoic acid	Sweaty	32	961	1, 3, 4
24	1-Octen-3-one	Mushroom-like	4	970	1, 4, 5, 10
25	(Z)-1,5-Octadien-3-one	Geranium-like	2	987	4, 5, 7, 9
26	Ethyl hexanoate	Fruity (apple)	8	1002	1, 2, 9
27	Octanal	Soapy, fatty	4	1006	1, 4, 9
28	4-Hydroxybutanoic acid	Sweaty	16	1018
29	Acetylpyrazine	Toasty	4	1030	1, 4, 7, 10
30	Phenylacetaldehyde	Honey-like	16	1042	2, 4, 5, 7
31	Tetrahydro-6-methyl-2 H-pyran-2-one	Coconut	2	1050	1,2
32	4-Methoxy-2,5-dimethyl-3 (2 H)-furanone	Caramel-like	16	1057	9
33	(E)-2-Octenal	Nutty, fatty	8	1062	1, 4, 5, 6, 7
34	4-Hydroxy-2,5-dimethyl-3(2 H)-furanone	Sweet, caramel	32	1022	2, 4, 9
35	2-Ethyl-3,5-dimethylpyrazine	Roasty	4	1080	4, 5, 7, 10
36	Linalool	Flowery	4	1092	1, 2
37	2-acetyl-2-thiazoline	Roasty	8	1108	4
38	2-Phenylethanol	Honey	128	1136	1, 2, 3, 4, 10
39	2-Propionyl-2-thiazole	Roasty	2	1125	4, 10
40	2,3-Dihydroxy-6-methyl-4 H-pyran-4-one	Caramel-sweet	64	1141	8
41	2,3-Diethyl-5-methylpyrazine	Earthy	4	1157	4, 7, 10
42	(E)-2-Nonenal	Fatty, green	4	1164	4, 5, 6, 7
43	Ethyl octanoate	Fruity, fatty	32	1201	1, 5
44	(E,E)-2,4-Nonadienal	Fatty	2	1220	1, 4, 5, 6
45	2-Methylpropanoic acid	Buttery, rancid	32	1221	4
46	Ethyl phenyl acetate	Fruity, sweet	8	1253	1
47	Y-Octalactone	Coconut-like	16	1261	1, 9
48	Decanol	Fatty	4	1269	1
49	2-Phenylacetic acid	Honey	8	1270	4
50	Benzoic acid	Sweaty	32	1287
51	δ-Octalactone	Coconut-like	2	1288	1, 2, 9
52	Butyrolactone	Caramel, sweet	4	1299	2
53	4-Vinylguaiacol	Curry, clove	4	1310	1, 10
54	(E,E)-2,4-Decadienal	Fatty	32	1313	1, 4, 5, 6
55	α-Copaene	Wood	2	1393	1
56	β-Damascenone	Sweet, fruity	8	1393	1, 4, 7, 9
57	Vanillin	Vanilla-like	16	1410	1, 4, 9
58	Y-Decalactone	Fruity, peach-like	4	1473	9
59	Ethyl octadecanoate	Flowery	4	2205	1

^a The compounds were identified by comparing them with reference substances on the basis of the following criteria: retention index on DB-5 as given in the table, mass spectra obtained by MS (EI), and odour quality as well as odour intensity perceived at the sniffing port. ^b Odour quality perceived at the sniffing port. ^c Reported in the literature as volatile compounds of bread in: ¹ Adams [18]; ² Elss et al. [19]; ³ Jensen et al. [20]; ⁴ Pozo-Bayon et al. [1]; ⁵ Rychlik & Grosch [8]; ⁶ Schieberle & Grosch [5]; ⁷ Schieberle & Grosch [21]; ⁸ Silva et al. [22]; ⁹ Tokitomo et al. [23]; ¹⁰ Zehentbauer & Grosch [24]. ^d The MS signal was too weak. The compound was later characterized by co-injection with reference compounds.