Table 2. The production of volatile organic compounds of pork large intestine with different cooking times

Compound	RI¹⁾	Cooking time (min)				SEM	Aroma description	Odor threshold (ppm)	References
Compound	RI¹⁾	40	120	180	240	SEM	Aroma description	Odor threshold (ppm)	References
Propenal	82.91	100,844	55,455.89	80,005.78	163,801.27	46,970.212	Pungent	0.0036	Chemical book (2016)
Methyl formate	75.00	88,311.06	82,097.86	68,926.26	107,400.01	36,676.450	Pleasant	130	Chemical book (2016)
Methyl pentanoate	89.00	34,038.25^a	17,528.71^ab	23,371.84^ab	5,163.85^b	6,079.401	Fruity	0.0022	Chemical book (2016)
Ethene, 1,2-dichloro, [E]-	88.20	18,552	12,936	5,115.73	2,937.31	8,421.834	Pleasant	17	Chemical book (2016)
2-Pentanol	92.43	11,609.95^a	3,785.65^b	5,370.25^b	1,501.59^b	1,047.442	Alcoholic	0.29	Chemical book (2016)
Methanol	77.37	9,096.96^a	5,245.72^ab	6,332.87^ab	4,621.71^b	945.892	Pungent	100	NCBI (2019)
Dichloromethane	76.55	7,587.68	5,514.41	2,669.88	1,590.76	2,008.755	Sweet, pleasant	23.4	NCBI (2019)
Bromochloromethane	88.28	3,046.95^a	2,543.68^ab	2,004.01^ab	1,124.84^b	389.723	Sweet chloroform-like	2100	Ruth (1986)
Methyl isobutyrate	80.59	1,955.38^a	812.51^b	619.02^b	342.76^b	107.376	Fruity	0.0019	Nagata and Takeuchi (2003)
1-Propanol	61.50	1,476.33^a	622.26^b	490.33^b	372.70^b	91.29	Alcoholic	0.094	Chemical book (2016)

Means within the same row with different superscript differ significantly (p<0.05).
RI, relevance index indicating the percentage of matching probability based on the comparison of Kovats retention index of the detected compound and the Kovats retention indices of known compounds from the AroChemBase library.