Table 2. Key Odorants Identified in Post-Fermentation Products from Sour and Sweet Whey from the Bioreactor Culture.

				concentration (μg/kg)d			OAVf
Compounda	Odorb	IR-DB 5c	IR-waxc	sour whey	sweet whey	OT in water (μg/kg)e	sour whey	sweet whey
2,3-butanedione	buttery	670	991	550 ± 11	610 ± 12	15	37	41
acetic acid	vinegar	691	1445	250,120 ± 128	5126 ± 89	99,000	2.5	<1
3-methylbutanal	malty	695	948	45 ± 2	0.8 ± 0.05	0.5	90	1.6
3-methyl-1-butanol	fruity	719	1204	121,511 ± 498	1546 ± 57	980	131	1.6
butanoic acid	cheesy	836	1620	18,523 ± 212	17,450 ± 400	1000	18	17
3-(methylthio)-propanal	boiled potato	908	1458	51 ± 0.8	48 ± 0.7	0.43	119	112
dimethyl trisulfide	cabbage	985	1377	7 ± 0.05	6.8 ± 0.05	0.099	71	69
phenylacetaldehyde	honey	1080	1644	12,040 ± 131	7105 ± 95	4	3010	1776
2-phenylethanol	rosy	1124	1920	7090 ± 91	4125 ± 52	240	29	17
phenylacetic acid	honey	1260	2568	1725 ± 32	3218 ± 38	1000	1.7	3.2

^aCompounds identified by comparison with reference compounds on the basis of the following criteria: retention index (RI), mass spectra obtained by MS (EI), and odor quality at the sniffing port.

^bOdor perceived at the sniffing port.

^cRetention indices on BD-5 and SUPELCOWAX 10 columns.

^dMean of triplicates ± standard deviations.

^eOT: odor thresholds in water.⁴⁴

^fOAV: odor activity values calculated by dividing the concentration of an analyte by its odor threshold value.