Table 6

	Ripening
	0	5	10	15	20
Phosphoserine	0.76 ± 0.02^d1)	1.26 ± 0.03^a	0.97 ± 0.02^b	0.41 ± 0.01^e	0.81 ± 0.02^c
Taurine	65.65 ± 1.46^a	61.00 ± 1.22^b	54.19 ± 1.15^c	41.35 ± 1.30^d	31.28 ± 0.62^e
Phosphoethanolamine	0.63 ± 0.01^d	3.70 ± 0.08^c	4.79 ± 0.06^a^b	4.92 ± 0.11^a	4.67 ± 0.11^b
Urea	1041.08 ± 26.11^a	237.46 ± 7.50^b	31.64 ± 0.76^c	22.34 ± 0.51^c	19.63 ± 0.52^c
Aspartic acid	12.85 ± 0.36^a	9.12 ± 0.18^b	7.19 ± 0.21^c	5.09 ± 0.11^d	1.34 ± 0.03^e
Threonine	24.12 ± 0.50^a	11.31 ± 0.28^b	3.61 ± 0.10^c	0.46 ± 0.01^d	0.39 ± 0.01^d
serine	31.99 ± 0.85^a	22.19 ± 0.62^b	11.82 ± 0.26^c	2.78 ± 0.06^d	0.56 ± 0.01^e
Asparagine	0.60 ± 0.01	2)	-	-	-
Glutamic acid	11.35 ± 0.24^a	9.52 ± 0.23^b	3.48 ± 0.11^c	1.48 ± 0.03^d	1.69 ± 0.04^d
Sarcocine	230.44 ± 7.33^a	195.60 ± 4.53^b	164.14 ± 3.76^c	168.69 ± 3.65^c	154.09 ± 3.86^d
?-aminoadipic acid	3.28 ± 0.07^b	3.80 ± 0.09^a	3.17 ± 0.10^b	2.64 ± 0.06^c	1.79 ± 0.04^d
Proline	17.23 ± 0.42^a	9.44 ± 0.19^c	10.75 ± 0.28^b	9.23 ± 0.21^c	7.88 ± 0.15^d
Glycine	27.89 ± 0.64^a	24.32 ± 0.65^b	24.16 ± 0.50^b	22.78 ± 0.54^c	19.59 ± 0.22^d
Alanine	23.73 ± 0.47^b	24.79 ± 0.57^b	31.68 ± 0.89^a	31.51 ± 0.83^a	20.22 ± 0.21^c
Citrulline	3.20 ± 0.07^c	3.64 ± 0.10^a	3.09 ± 0.08^c	3.44 ± 0.04^b	2.82 ± 0.06^d
?-aminobutyric acid	0.30 ± 0.01^d	0.31 ± 0.01^d	0.36 ± 0.01^c	0.42 ± 0.01^b	0.44 ± 0.01^a
Valine	5.65 ± 0.12^a	4.78 ± 0.11^b	5.56 ± 0.12^a	5.59 ± 0.13^a	3.50 ± 0.10^c
Cystine	0.00 ± 0.00e	0.43 ± 0.01^c	0.34 ± 0.01^d	0.67 ± 0.01^b	0.90 ± 0.03^a
Methionine	4.29 ± 0.10^a	2.53 ± 0.07^b	2.32 ± 0.05^c	1.02 ± 0.03^d	0.25 ± 0.01^e
Isoleucine	3.47 ± 0.08^a	2.27 ± 0.05^b	2.33 ± 0.05^b	1.56 ± 0.03^c	0.59 ± 0.02^d
Leucine	6.41 ± 0.15^a	4.38 ± 0.05^b	4.42 ± 0.09^b	3.67 ± 0.10^c	1.19 ± 0.03^d
Tyrosine	3.02 ± 0.08^a	2.33 ± 0.05^c	2.87 ± 0.08^b	1.69 ± 0.03^d	-
phenylalanine	3.44 ± 0.08^a	3.40 ± 0.09^a^b	3.29 ± 0.07^b	2.97 ± 0.05^c	-
?-alanine	32.62 ± 0.62^a	26.71 ± 0.56^b	21.46 ± 0.36^c^d	22.20 ± 0.47^c	20.96 ± 0.38^d
?-amino-n-butyric acid	0.22 ± 0.00^c	0.45 ± 0.01^b	0.44 ± 0.01^b	0.52 ± 0.01^a	0.10 ± 0.00^d
Histidine	4.53 ± 0.05^a	3.36 ± 0.11^b	3.42 ± 0.10^b	3.15 ± 0.07^c	1.28 ± 0.02^d
1-methylhistidine	0.21 ± 0.00	-	-	-	-
Carnosine	0.68 ± 0.02^b	0.72 ± 0.02^a	0.36 ± 0.01^c	0.26 ± 0.01^d	0.25 ± 0.01^d
Anserine	0.14 ± 0.00^b	0.11 ± 0.00^c	0.18 ± 0.00^a	0.11 ± 0.00^c	0.05 ± 0.00^d
Ornitine	3.99 ± 0.12^c	4.53 ± 0.09^b	4.93 ± 0.14^a	4.10 ± 0.12^c	2.50 ± 0.05^d
Lysine	11.96 ± 0.24^a	9.95 ± 0.23^b	9.27 ± 0.21^c	7.31 ± 0.15^d	2.99 ± 0.03^e
Ethanolamine	3.16 ± 0.07^b	2.52 ± 0.08^c	1.65 ± 0.04^d	0.76 ± 0.02^e	4.11 ± 0.08^a
Arginine	3.23 ± 0.09^a	2.56 ± 0.06^b	2.14 ± 0.07^d	2.32 ± 0.07^c	1.52 ± 0.03^e
Ammomia	53.28 ± 2.54^e	1133.72 ±22.12^d	1269.45 ± 27.32^c	1307.02 ± 20.22^b	1449.96 ± 33.59^a
Total	1582.11 ± 34.50^a	688.48 ± 16.15^b	420.04 ± 9.00^c	375.41 ± 8.42^d	307.50 ± 8.54^e

1) Values are means ± SD (n = 3). Values with different superscripts in the same row are significantly different at P<0.05 by Duncan's multiple range test.
2) Not detected.

Table 6: Free amino acid contents of skate during different ripening periods (mg/100 g).