Physicochemical changes of pepsin-solubilized and insoluble collagen in jumbo squid (Dosidicus gigas) muscle after cooking process

Figures & data

Figure 3. FTIR spectrum analysis of PSC extracted from fresh and cooked jumbo squid (Dosidicus gigas) muscle. (a) Fins; (b) arms; and (c) mantle.

Table 1. Changes in collagen solubility (mg/100 g muscle) of fresh muscle (mantle, fins and arms) of jumbo squid (Dosidicus gigas) subjected to a cooking process.

	*CT		**PSC		**IC
Anatomical region	Fresh	Cooked	Fresh	Cooked	Fresh	Cooked
Fins	550.0^bB	700^aB	17.85^aB	8.31^aC	456^aA	2.17^bB
Mantle	530^bB	200^aC	17.67^aB	18.40^aB	175.31^aB	15.70^bA
Arms	1520^aA	1050^bA	361.68^aA	130.05^bA	261.3^aC	41.34^bA

Results represent an average of three determinations.

*Protein content was calculated by micro-Kjeldahl method.

**Collagen content was obtained by multiplying the hydroxyproline content times by a factor 7.14 (Ando y col., 2006).

Different capital letters in the same column indicate significant differences (p < 0.05).

Different lowercase letters in the same line indicate significant differences (p < 0.05).

Figure 1. SDS–polyacrylamide gel electrophoresis of PSC extracted from fresh and cooked jumbo squid (Dosidicus gigas) muscle. (A) Molecular weight markers, kDa; (B) PSC from fresh fins; (C) PSC from cooked fins; (D) PSC from fresh mantle; (E) PSC from cooked mantle; (F) PSC from fresh arms; and (G) PSC from cooked arms.

Figure 2. OFFGEL-electrophoresis fractionation of PSC extracted from fish and cooked jumbo squid (Dosidicus gigas) muscle.

Table 2a. Amino-acid profile (residues/1000 amino-acid residues) of PSC extracted from fresh and cooked muscle of jumbo squid (Dosidicus gigas).

	Fins		Mantle		Arms
Amino acids	Fresh	Cooked	Fresh	Cooked	Fresh	Cooked
Asp	98	109	65	113	75	126
Arg	79	68	66	73	71	88
Ala	78	76	80	80	86	ND
Cys	35	ND	37	ND	35	ND
Glu	63	115	85	128	94	141
Gly	276	61	181	58	209	30
His	ND	23	ND	ND	ND	ND
Hyp	73	38	74	50	51	41
Ile	ND	63	32	65	30	73
Leu	33	65	26	69	28	ND
Lys	48	75	39	84	39	93
Met	34	33	30	ND	29	48
Phe	ND	36	4	38	ND	42
Pro	139	68	144	76	125	113
Ser	53	62	45	61	47	75
Thr	ND	65	70	66	78	81
Tyr	ND	ND	ND	ND	ND	ND
Val	ND	44	24	41	ND	47

Results represent an average of three determinations. Standard deviations were in all cases lower than 5%.

PSC: pepsin-solubilizated collagen; ND: not detected.

Table 2b. Amino-acid profile (residues/1000 amino-acid residues) of IC extracted from fresh and cooked muscle of jumbo squid (Dosidicus gigas).

	Fins		Mantle		Arms
Amino acids	Fresh	Cooked	Fresh	Cooked	Fresh	Cooked
Asp	79	83	83	112		110
Arg	64	ND	69	72	72	76
Ala	78	125	81	84	77	86
Cys	36	51	40	ND	45	ND
Glu	73	54	80	104	70	104
Gly	198	67	221	69	219	71
His	ND	26	17	ND	ND	ND
Hyp	95	28	47	43	84	22
Ile	ND	67	31	72	ND	77
Leu	24	38	25	53	29	52
Lys	50	87	49	110	67	106
Met	37	54	36	61	46	62
Phe	ND	34	ND	ND	ND	ND
Pro	124	139	48	85	79	97
Ser	42	54	46	60	51	62
Thr	98	66	126	75	79	77
Tyr	ND	ND	ND	ND	ND	ND
Val	ND	27	ND	ND	ND	ND

Results represent an average of three determinations. Standard deviations were in all cases lower than 5%.

IC: insoluble collagen; ND: not detected.

Table 3. Pyridinoline content (mmol/mol collagen*) in connective tissue extracted from fresh and cooked muscle (fins, mantle, and arms) of jumbo squid (Dosidicus gigas).

Anatomic region	Fresh muscle	Cooked muscle
Fins	6.59 ± 1.41^aA	3.95 ± 0.56^bA
Mantle	1.88 ± 0.24^aB	0.68 ± 0.03 ^bC
Arms	5.73 ± 0.32 ^aA	1.05 ± 0.19 ^bB

Results represent an average of three determinations.

Different capital letters in the same column indicate significant differences (p < 0.05).

Different lowercase letters in the same line indicate significant differences (p < 0.05).

*Collagen content was obtained by multiplying the hydroxyproline content in CT times by a factor 7.14 (Ando et al., 2006).

Table 4. Denaturation temperatures (DT) and enthalpies (ΔH) of PSC and IC extracted fresh and cooked muscle of jumbo squid (Dosidicus gigas).

	PSC (DT-°C/ΔH-Jg^−1)		IC (DT-°C/ΔH-Jg^−1)
Anatomical region	Fresh	Cooked	Fresh	Cooked
Fins	110/3.94	82.86/16.12	114.41/4.51	91.85/5.75
Mantle	107.39/16.57	75.96/1.98	107.17/20.58	87.35/2.78
Arms	84.67/6.68	76.30/5.83	116.04/6.01	84.51/6.46