A Rapid and Accurate Extraction Procedure for Analysing Free Amino Acids in Meat Samples by GC-MS

Table 2

Amino acid content (mg per 100 g sample dry matter) extracted from fresh loin and dry-cured ham samples by using two extraction procedures, with stomacher () and mixer mill ().

	Fresh loin			Dry-cured ham			(fresh loin versus dry-cured ham)
Alanine	41.82 ± 15.38	52.43 ± 19.48	0.500	234.86 ± 31.25	307.04 ± 22.74	0.032		<0.001
Glycine	<LOQ.	<LOQ.	—	69.49 ± 11.51	113.69 ± 10.23	0.008	<0.001
Valine	11.20 ± 1.63	8.80 ± 3.04	0.295	177.39 ± 28.43	242.10 ± 5.44	0.018	<0.001
Leucine	12.22 ± 2.10	11.77 ± 2.06	0.806	181.12 ± 29.86	254.25 ± 4.47	0.014	<0.001
Isoleucine	11.30 ± 1.45	10.75 ± 1.81	0.705	130.22 ± 20.76	174.52 ± 2.58	0.021	<0.001
Proline	36.74 ± 1.12	29.64 ± 0.97	0.001	186.77 ± 24.13	244.28 ± 15.73	0.026	<0.001
Methionine	29.38 ± 2.94	30.26 ± 9.03	0.881	77.04 ± 11.38	99.87 ± 0.41	0.026	<0.001
Serine	30.40 ± 1.46	27.98 ± 1.41	0.108	156.65 ± 30.08	244.85 ± 21.07	0.014	<0.001
Threonine	32.84 ± 2.87	37.13 ± 10.87	0.545	293.38 ± 66.02	488.86 ± 31.09	0.010	<0.001
Phenylalanine	28.23 ± 0.96	27.48 ± 4.83	0.804	118.40 ± 20.92	172.00 ± 2.26	0.012	<0.001
Aspartic acid	43.67 ± 4.24	43.43 ± 6.56	0.960	201.95 ± 38.71	281.37 ± 11.33	0.027	<0.001
Hydroxyproline	n.d.	10.24 ± 2.34	0.002	17.45 ± 1.17	20.48 ± 2.01	0.087	<0.001
Cysteine	100.99 ± 22.64	103.71 ± 26.27	0.898	154.55 ± 29.13	206.79 ± 23.52	0.073	0.001
Glutamic acid	n.d.	42.28 ± 2.86	<0.001	352.89 ± 80.64	520.02 ± 11.65	0.024	<0.001
Asparagine	56.75 ± 1.06	44.28 ± 2.10	0.001	47.83 ± 2.29	37.09 ± 0.90	0.002	0.059
Lysine	69.53 ± 8.15	48.94 ± 3.35	0.016	356.36 ± 91.72	554.92 ± 109.00	0.073	<0.001
Glutamine	148.33 ± 21.24	153.93 ± 28.16	0.797	69.34 ± 1.12	54.27 ± 0.90	<0.001	<0.001
Arginine	n.d.	n.d.	—	130.22 ± 8.08	224.19 ± 4.81	<0.001	<0.001
Histidine	n.d.	n.d.	—	119.13 ± 5.96	145.60 ± 7.29	0.008	<0.001
Tyrosine	66.39 ± 12.21	46.71 ± 6.01	0.066	91.05 ± 12.70	119.52 ± 2.73	0.019	<0.001
Tryptophan	n.d.	n.d.	—	26.82 ± 7.49	207.58 ± 3.76	<0.001	—
Cystine	n.d.	n.d.	—	n.d.	n.d.	—	—

LOQ: limit of quantification.
n.d.: not detected.