Monitoring oxidative stability and changes in key volatile compounds in edible oils during ambient storage through HS-SPME/GC–MS

Figures & data

Table 1. Quality indices and fatty acid compositions of edible oils (mean ±SD, n = 3).

Oil sample	PV(meq/kg)	AV(mg/g)	SV (mg/g)	IV (g/100g)	Fatty acid composition (relative %)
					Palmitic	Stearic	Oleic	Linoleic	Linolenic
Rapeseed oil	-	-	175.12 ± 0.1	113.71 ± 0.01	4.34 ± 0.00	2.03 ± 0.00	67.18 ± 0.01	20.56 ± 0.01	5.90 ± 0.00
Peanut oil	-	-	187.03 ± 0.1	105.51 ± 0.05	11.08 ± 0.01	3.95 ± 0.01	42.57 ± 0.01	37.16 ± 0.01	0.00 ± 0.00
Soybean oil	-	-	191.22 ± 0.3	137.53 ± 0.01	10.63 ± 0.01	4.08 ± 0.00	24.47 ± 0.01	54.92 ± 0.01	5.90 ± 0.01
Linseed oil	-	-	195.02 ± 0.2	178.38 ± 0.05	5.08 ± 0.01	3.20 ± 0.00	30.98 ± 0.01	16.87 ± 0.01	43.88 ± 0.01

“ –” means less than detection limit

Table 2. Comparison of the time when edible oils reached different PVs (mean ± SD, n = 3).

Oil sample	Oxidation time (days)
	3 meq/kg	20 meq/kg	40 meq/kg	60(meq/kg	80 meq/kg	100 meq/kg
Rapeseed oil	2 ± 0.20	45.75 ± 0.20	90.5 ± 0.20	125 ± 0.20	150.5 ± 0.10	170.5 ± 0.30
Peanut oil	1.5 ± 0.10	25.5 ± 0.10	58 ± 0.10	85 ± 0.10	105.5 ± 0.20	119.25 ± 0.20
Soybean oil	1 ± 0.10	17.5 ± 0.10	36 ± 0.10	53 ± 0.10	67 ± 0.10	78.5 ± 0.10
Linseed oil	0.5 ± 0. 05	7.50 ± 0.10	15 ± 0.10	21 ± 0.10	26 ± 0.10	30.25 ± 0.10

Table 3. Changes in key volatile compounds in rapeseed oil during ambient storage (mean ± SD, n = 3).

Volatile compounds	Relative peak area (%)
	3 meq/kg	20 meq/kg	40 meq/kg	60 meq/kg	80 meq/kg	100 meq/kg
Pentanal	0.15 ± 0.008	0.28 ± 0.01	0.63 ± 0.03	0.93 ± 0.04	1.74 ± 0.07	1.07 ± 0.04
Hexanal	1.34 ± 0.06	4.4 ± 0.2	7.07 ± 0.3	7.33 ± 0.3	7.63 ± 0.3	9.74 ± 0.4
Heptanal	0.1 ± 0.006	0.24 ± 0.012	0.45 ± 0.02	0.69 ± 0.03	0.91 ± 0.04	1.11 ± 0.05
Octanal	0.97 ± 0.04	1.26 ± 0.05	2.44 ± 0.1	1.99 ± 0.05	1.65 ± 0.07	1.41 ± 0.06
Nonanal	3.1 ± 0.1	6.55 ± 0.3	11.94 ± 0.5	6.5 ± 0.3	2.32 ± 0.1	3.02 ± 0.2
Decanal	0.19 ± 0.006	0.56 ± 0.02	1.31 ± 0.05	1.06 ± 0.05	0.65 ± 0.03	0.3 ± 0.01
2-Butenal	0.1 ± 0.004	0.32 ± 0.015	0.56 ± 0.02	0.78 ± 0.03	1.02 ± 0.04	2.48 ± 0.1
(E)-2-pentenal	0.5 ± 0.002	0.86 ± 0.04	1.35 ± 0.07	2.43 ± 0.11	3.43 ± 0.13	1.21 ± 0.05
(E)-2-heptenal	0.56 ± 0.03	0.87 ± 0.04	1.45 ± 0.07	2.06 ± 0.1	2.34 ± 0.11	2.41 ± 0.11
E-2-decenal	0.02 ± 0.001	0.04 ± 0.002	0.08 ± 0.004	0.11 ± 0.005	0.13 ± 0.005	0.15 ± 0.006
(E,E)-2,4 -Heptadienal	0.1 ± 0.005	0.15 ± 0.006	0.42 ± 0.02	0.51 ± 0.02	0.71 ± 0.034	0.84 ± 0.04
Benzaldehyde	0.92 ± 0.045	1.12 ± 0.06	1.12 ± 0.06	0.71 ± 0.034	nd	nd
1-Pentanol	nd	nd	0.25 ± 0.01	0.33 ± 0.012	0.38 ± 0.015	0.41 ± 0.02
1-Octanol	0.1 ± 0.005	0.13 ± 0.006	0.15 ± 0.006	0.17 ± 0.007	0.19 ± 0.008	0.21 ± 0.01
Acetic acid	nd	2.3 ± 0.1	3.26 ± 0.14	3.01 ± 0.14	2.73 ± 0.12	2.62 ± 0.13
Hexanoic acid	0.16 ± 0.008	2.62 ± 0.12	1.67 ± 0.08	0.78 ± 0.035	0.32 ± 0.015	0.28 ± 0.014
Nonanoic acid	0.29 ± 0.014	0.48 ± 0.02	1.1 ± 0.05	0.95 ± 0.04	0.87 ± 0.04	0.86 ± 0.04
Dodecane	0.88 ± 0.04	2.13 ± 0.1	3.13 ± 0.12	1.12 ± 0.06	1.09 ± 0.05	1.41 ± 0.07
D-Limonene	0.72 ± 0.035	1.68 ± 0.08	1.17 ± 0.06	0.64 ± 0.03	1.48 ± 0.07	1.6 ± 0.08

nd, non-detectable

Table 4. Odour contribution of volatile components of four edible oil samples.

Key compounds	Odour threshold (ng/L)	ROAV				Sensory description
		Rapeseed oil	Peanut oil	Soybean oil	Linseed oil
Pentanal	38	1.53	1.13	11.54	1.96	Pungent, almond, malt
Hexanal	51	10.17	100	11.39	23.73	Grass, green, rancid, tallowy, fat
Heptanal	46	0.84	0.75	3.34	nd	Rancid, fatty, citrus
Octanal	9.3	40.37	26.73	41.24	42.82	Fatty, soapy, green, oily, fresh
Nonanal	12	100	85.48	100	100	Citrus, green, fatty, oily, soapy, tallowy, fruity
Decanal	4.3	17.1	nd	19.11	40.75	Floral, orange peel, soapy, tallowy, green, fresh
2-Butenal	350	0.11	nd	nd	0.61	Pungent
(E)-2-pentenal	1500	0.13	nd	nd	0.14	Strawberry, fruity, tomato, pungent, apple
(E)-2-heptenal	88	2.46	1.07	3.61	1.21	Fatty, soapy, almond, oily
(E)-2-octenal	20	nd	2.14	4.66	nd	Green, nutty, fatty, oily
E-2-decenal	3.2	2.42	2.68	10.27	nd	Tallowy, orange-like
(E,E)-2,4-heptadienal	38	1.02	nd	nd	2.80	Fatty
Benzaldehyde	186	1.91	3.82	1.80	2.65	Almond, burnt sugar
1-Pentanol	3590	nd	0.016	0.11	0.05	Balsamic
1-Hexanol	360	nd	nd	nd	0.5	Green, floral
1-Octanol	73	0.53	0.43	0.52	nd	Chemical, metallic, burnt
Acetic acid	1384	nd	0.12	nd	0.26	Sour
Hexanoic acid	3000	0.02	0.02	0.06	0.11	Sour, fatty, sweaty, cheese
Nonanoic acid	12	9.35	nd	10.96	nd	Green, fatty
Dodecane	5300	0.064	0.14	0.026	0.15	Gasoline-like
D-Limonene	718	0.38	0.57	0.2	1.06	Lemon, orange
2-Pentylfuran	181	nd	1.07	2.75	1.47	Butter, green beans

Mean values of odour thresholds in air^[36,39] sensory description referred to literature^[40,41]; nd, non-detectable. Only flavour components with ROAV ≥ 0.1 in one of the four edible oil samples are presented.

Table 5. Correlation analysis between PV and key volatile compounds.

Key volatile compounds	Correlation coefficient
	Rapeseed oil	Peanut oil	Soybean oil	Linseed oil
Pentanal	0.852*	0.970**	0.806	0.705
Hexanal	0.935**	0.969**	0.995**	0.688
Heptanal	0.935**	0.999**	0.993**	0.662
Octanal	0.281	0.362	0.472	0.567
Nonanal	−0.291	0.969**	0.981**	0.681
Decanal	0.053	0.000	−0.738	0.321
2-Butenal	0.898*	0.000	0.000	0.906*
(E)-2-Pentenal	0.598	0.000	0.000	0.972**
(E)-2-Heptenal	0.939**	0.557	0.985**	0.964**
(E)-2-Octenal	0.000	0.991**	0.997**	0.000
E-2-Decenal	0.992**	0.990**	0.990**	0.000
(E,E)-2,4–Heptadienal	0.991**	0.000	0.662	0.990**
Benzaldehyde	−0.867*	−0.901*	−0.496	−0.228
1-Pentanol	0.945**	0.914*	0.882*	0.997**
1-Hexanol	0.000	−0.007	0.000	0.403
1-Octanol	0.995**	0.982**	0.996**	0.000
Acetic acid	0.620	0.749	0.623	0.767
Hexanoic acid	−0.414	0.965**	0.962**	0.810
Nonanoic acid	0.662	0.984**	0.752	0.967**
Dodecane	−0.173	−0.817*	−0.524	0.029
D-Limonene	0.379	−0.797	−0.176	−0.396
2-Pentylfuran	0.000	−0.153	−0.493	−0.730

** Correlation is significant at 0.01 level; * Correlation is significant at 0.05 level.

Amoore, J. E.; Hautala, E. Odor as an Ald to Chemical Safety: Odor Thresholds Compared with Threshold Limit Values and Volatilities for 214 Industrial Chemicals in Air and Water Dilution. J. Appl. Toxicol. 1983, 3, 272–290. DOI: 10.1002/(ISSN)1099-1263.

 PubMed Web of Science ®Google Scholar

Van Gemert, L. J.; Nettenbreijer, A. H. Compilation of Odour Threshold Values in Air and Water. National Institute for Water Supply, Voorburg, Central Institute for Nutrition and Food, Research: Zeist, The Netherlands, 1977.

 Google Scholar

Petersen, K. D.; Kleeberg, K. K.; Jahreis, G.; Fritsche, J. Assessment of the Oxidative Stability of Conventional and High-Oleic Sunflower Oil by Means of Solid-Phase Microextraction-Gas Chromatography. Int. J. Food Sci. Nutr. 2012, 63, 160–169. DOI: 10.3109/09637486.2011.609158.

 PubMed Web of Science ®Google Scholar

Petersen, K. D.; Kleeberg, K. K.; Jahreis, G.; Busch-Stockfisch, M.; Fritsche, J. Comparison of Analytical and Sensory Lipid Oxidation Parameters in Conventional and High-Oleic Rapeseed Oil. Eur. J. Lipid Sci. Technol. 2012, 114, 1193–1203. DOI: 10.1002/ejlt.v114.10.

 Web of Science ®Google Scholar