. 2020 Sep 29;9(10):1377. doi: 10.3390/foods9101377

Table 2.

Free amino acid content of raw and canned European eels packed in olive oil or spiced olive oil throughout the different steps of the canning process and after 2 and 12 months of storage (expressed as mg/100 g muscle).

	Raw	Frying (in Olive Oil)	Sterilization		Storage 2 Months		Storage 12 Months
	Raw	Frying (in Olive Oil)	Olive Oil	Spiced Olive Oil	Olive Oil	Spiced Olive Oil	Olive Oil	Spiced Olive Oil
*NON-ESSENTIAL AMINO ACIDS*
Aspartic acid	14.24 ± 0.54 ^a	11.97 ± 2.54 ^a	37.49 ± 2.01 ^b	39.39 ± 5.66 ^b	29.80 ± 1.11 ^c	32.33 ± 1.38 ^c	32.26 ± 0.40 ^c	23.96 ± 0.43 ^d
Glutamic acid	21.60 ± 1.75 ^a,b	23.21 ± 0.95 ^a,b	21.35 ± 0.46 ^a,c	22.79 ± 4.38 ^a,b	20.62 ± 1.38 ^a,c,d	24.02 ± 0.36 ^b	18.79 ± 0.20 ^c,d	17.80 ± 1.26 ^d
Hydroxyproline	0.86 ± 0.04 ^a	0.82 ± 0.19 ^a	0.84 ± 0.07 ^a	0.85 ± 0.20 ^a	0.81 ± 0.03 ^a	0.90 ± 0.04 ^a	1.32 ± 0.14 ^b	1.77 ± 0.24 ^c
Serine	3.81 ± 0.03 ^a	3.33 ± 0.23 ^a	2.26 ± 0.27 ^b,c	2.69 ± 0.33 ^b	1.98 ± 0.01 ^c	3.38 ± 0.19 ^a	2.19 ± 0.15 ^b,c	2.31 ± 0.32 ^b,c
Glycine	50.24 ± 2.29 ^a	35.82 ± 3.40 ^b	48.26 ± 1.24 ^a	54.17 ± 6.91 ^a	37.33 ± 2.20 ^b	50.08 ± 5.24 ^a	29.85 ± 2.48 ^c	33.74 ± 2.34 ^b
Arginine	80.58 ± 6.07 ^a	100.67 ± 6.97 ^b	115.08 ± 7.07 ^c	130.44 ± 3.88 ^d	137.07 ± 16.04 ^d	143.58 ± 2.32 ^d	319.70 ± 5.93 ^e	247.61 ± 11.62 ^f
Alanine	12.37 ± 1.13 ^a	14.29 ± 0.92 ^b	13.90 ± 0.50 ^a,b	18.74 ± 0.26 ^c	13.58 ± 1.36 ^a,b	17.78 ± 1.02 ^c	13.57 ± 1.12 ^a,b	17.84 ± 0.07 ^c
Proline	2.68 ± 0.28 ^a	5.99 ± 0.52 ^c,d	5.31 ± 0.30 ^b,c	4.82 ± 0.19 ^b	5.52 ± 0.56 ^b,c	6.81 ± 0.67 ^e	5.66 ± 0.32 ^b,c	6.46 ± 0.57 ^d,e
Tyrosine	5.98 ± 0.32 ^a	10.29 ± 0.94 ^c	10.54 ± 0.30 ^c	9.73 ± 0.26 ^c	8.40 ± 0.11 ^b	9.98 ± 0.20 ^c	8.55 ± 0.38 ^b	10.78 ± 0.35 ^c
Taurine	91.63 ± 6.62 ^a	119.00 ± 14.70 ^b	103.84 ± 6.23 ^a,b	100.06 ± 23.40 ^a,b	76.71 ± 11.62 ^c	100.57 ± 14.61 ^a,b	66.77 ± 6.73 ^c	60.23 ± 1.73 ^c
Ornithine	1.58 ± 0.08 ^a	0.33 ± 0.03 ^b	0.73 ± 0.12 ^c	0.48 ± 0.15 ^b,d	0.65 ± 0.03 ^c,d	0.61 ± 0.15 ^c,d	0.54 ± 0.06 ^d	0.43 ± 0.05 ^b,c
*Total non-essential amino acids (NEAA)*	286.31 ± 19.25 ^a	325.14 ± 21.72 ^a,b	346.70 ± 35.87 ^b	373.26 ± 20.80 ^b,d	332.48 ± 4.31 ^a,b	357.76 ± 30.75 ^b	499.09 ± 14.42 ^c	408.42 ± 28.36 ^d
*ESSENTIAL AMINO ACIDS*
Histidine	222.76 ± 6.99 ^a	225.23 ± 13.63 ^a,c	264.47 ± 3.01 ^b	270.09 ± 5.48 ^b	279.62 ± 4.74 ^b	259.97 ± 1.19 ^b,c	96.36 ± 8.98 ^c	139.64 ± 7.28 ^e
Threonine	9.07 ± 0.06 ^a	9.61 ± 1.42 ^a	13.85 ± 1.29 ^b	13.91 ± 0.15 ^b	14.12 ± 0.53 ^b	12.51 ± 0.39 ^b	12.71 ± 0.55 ^b	12.22 ± 1.08 ^b
Valine	1.73 ± 0.15 ^a	4.40 ± 0.71 ^b	10.81 ± 0.73 ^d	7.46 ± 0.48 ^c	6.64 ± 0.05 ^c	7.40 ± 0.35 ^c	26.73 ± 4.01 ^e	11.26 ± 1.47 ^d
Isoleucine	2.47 ± 0.32 ^a	4.36 ± 0.50 ^b,c,e	3.91 ± 0.47 ^b,c,d	3.77 ± 0.19 ^b,d	3.09 ± 0.02 ^a,d	4.65 ± 0.41 ^c,e	3.90 ± 0.36 ^c,b,d	4.68 ± 0.63 ^e
Leucine	4.08 ± 0.32 ^a	6.20 ± 0.59 ^b	6.83 ± 0.33 ^b,c	6.70 ± 0.55 ^b	4.27 ± 0.02 ^a	7.67 ± 0.01 ^c	4.77 ± 0.08 ^a	6.05 ± 0.10 ^b
Phenylalanine	4.83 ± 1.18 ^a,b,c	5.36 ± 0.94 ^c	3.84 ± 0.98 ^a,b	5.36 ± 1.06 ^c,d	3.69 ± 0.24 ^a,b	6.60 ± 0.28 ^d	3.59 ± 0.10 ^a	5.11 ± 0.52 ^b,c
Lysine	4.48 ± 0.52 ^a	23.33 ± 2.53 ^b	23.32 ± 2.70 ^b	24.89 ± 1.35 ^b,d	22.55 ± 2.15 ^b	28.35 ± 1.36 ^d	16.79 ± 0.85 ^c	17.17 ± 0.72 ^c
Tryptophan	5.24 ± 0.17 ^a	6.90 ± 0.38 ^b	7.06 ± 0.43 ^b	7.15 ± 1.06 ^b	6.91 ± 0.17 ^b	7.48 ± 0.66 ^b	7.77 ± 0.17 ^b	6.95 ± 1.00 ^b
*Total essential amino acids (EAA)*	255.53 ± 6.59 ^a	288.41 ± 17.03 ^b	335.50 ± 0.58 ^c	326.25 ± 13.43 ^c	340.90 ± 7.44 ^c	316.30 ± 12.03 ^c	174.83 ± 3.23 ^d	186.71 ± 8.21 ^d
*EAA/NEAA ratio*	0.90 ± 0.08 ^a	0.95 ± 0.17 ^a	0.94 ± 0.04 ^a	0.94 ± 0.13 ^a	1.03 ± 0.04 ^a	0.90 ± 0.20 ^a	0.35 ± 0.04 ^b	0.44 ± 0.03 ^b
*Total free amino acids*	541.83 ± 12.66 ^a	601.49 ± 25.99 ^b	702.91 ± 0.71 ^c	699.52 ± 7.37 ^c	673.38 ± 3.13 ^c,d	713.84 ± 10.36 ^c	661.21 ± 36.39 ^d	611.12 ± 0.45 ^b

^a–f Mean values of at least three determinations ± standard deviation with different superscripts in the same row were significantly different (p < 0.05).