Preparation and characterization of protein isolate from Yellowfin tuna Thunnus albacares roe by isoelectric solubilization/precipitation process

Table 4 Total amino acid (g/100 g protein) composition of FDC, RAIs and RPIs prepared by ISP process and positive controls

Amino acid	FDC	RAI-11	RAI-12	RPI-1	RPI-2	RPI-3	RPI-4	Casein	Hb
Protein content (%)^a	81.6d	87.2c	82.8d	89.9b	86.9c	90.1b	89.5b	89.1b	96.3a
Asp	8.7d	8.9cd	8.8cd	9.3b	9.1bc	9.3b	9.2b	8.2e	11.2a
Thr^b	5.0e	5.1ab	5.0d	5.1abc	5.1ab	5.1a	5.0cd	3.9g	4.7f
Ser	5.6a	5.3c	5.4b	5.2cd	5.2d	5.4b	5.0e	4.0g	4.4f
Glu	13.1d	13.8b	13.7c	12.7e	12.4h	12.4g	12.5f	22.1a	9.3i
Pro^c	6.1c	7.7b	7.9b	5.7d	5.1e	4.7g	4.9ef	10.0a	4.0de
Gly^c	4.9c	6.0b	6.4a	4.5ef	4.2f	4.3ef	4.3ef	2.4g	4.6de
Ala^c	6.6c	6.1d	6.2d	6.7bc	6.9b	6.8b	6.8bc	3.8e	9.0a
Cys	0.7b	0.8b	1.1a	0.8b	0.9b	0.3d	0.2d	0.5c	0.1d
Val^bc	6.3d	6.7c	6.3cd	6.5cd	6.5cd	6.6c	6.6cd	7.3b	10.2a
Met^bc	2.9c	2.5d	2.5d	2.9b	3.0b	3.1a	3.1a	1.3e	0.0f
Ile^bc	5.4d	4.9e	4.5f	5.8c	6.2ab	6.1b	6.3a	5.7c	0.8g
Leu^bc	8.6f	8.0g	7.5h	8.8e	9.3c	9.3bc	9.4b	9.1d	13.3a
Tyr	3.4a	2.6c	3.4a	3.2b	3.1b	3.4a	3.2b	1.2d	0.3e
Phe^bc	4.4h	4.6f	4.3i	4.5g	4.7e	4.8d	4.9c	5.0b	7.6a
His^b	3.4b	3.2c	3.1c	3.2c	3.1c	3.1c	3.2c	2.9d	6.4a
Lys^b	8.5c	7.6e	7.3f	8.5c	8.9b	8.8b	8.9b	8.3d	10.3a
Arg^b	6.6a	6.4a	6.6a	6.6a	6.4a	6.4a	6.5a	4.4b	3.8c
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TAA	100.2	100.2	100.0	100.0	100.1	99.9	100.0	100.1	100.0
EAA	51.1	49.0	47.1	51.9	53.2	53.3	53.9	47.9	57.1
EAA/NEAA	1.04	0.96	0.89	1.08	1.14	1.14	1.17	0.92	1.33
Hydrophobic amino acid	45.2	46.5	45.6	45.4	45.9	45.7	46.3	44.6	49.5

TAA total amino acid, EAA essential amino acids, NEAA non essential amino acids
FDC freeze-dried concentrate; RAI-11 and RAI-12, roe alkaline insolubles after alkaline solubilization at pH 11 or 12 respectively. RPI-1 and RPI-2, roe protein isolate adjusting at pH 4.5 and 5.5, respectively, after alkaline solubilization at pH 11; RPI-3 and RPI-4, roe protein isolate adjusting at pH 4.5 and 5.5, respectively, after alkaline solubilization at pH 12; Hb hemoglobin
Values are means ± standard deviation of duplicate determinations
Means with different letters within the same row are significantly different at p < 0.05 by Duncan’s multiple range test
^aBased on dry weight
^bEssential amino acids for infant
^cHydrophobic amino acids

ISSN: 2234-1757