Chemical quality and sensory profile of the Mediterranean farmed fish shi drum (Umbrina cirrosa) as affected by its dietary protein/fat levels

Figures & data

Table 1. Gross composition and fatty acid profile of the feeds fed to shi drum.

	DIET A (450/160)	DIET B (480/120)
Gross composition, g kg^−1
Moisture	72.8	85.5
Protein	448.9	478.0
Fat	163.4	123.6
Ash	85.0	76.9
NFE	302.7	321.5
Energy, kJ	185.2	174.9
P/E, mg kJ^−1	24.24	27.32
Fatty acids  composition, g kg^−1
14:0	29.2	31.7
16:0	137.8	147.3
16:1ω-9	34.2	34.4
17:0	5.20	5.40
18:0	12.1	13.6
18:1ω-9	400.1	364.0
18:1ω-7	36.2	32.1
18:2ω-6	205.1	216.0
18:3ω-3	18.2	27.1
20:1ω-9	19.2	17.2
20:2ω-9	4.70	4.20
20:5ω-3	42.6	48.6
22:1ω-9	7.90	10.2
22:5ω-3	5.10	4.90
22:6ω-3	42.1	42.8
SFA	184.5	198.1
MUFA	497.7	457.9
ω3-PUFA	108.0	123.5
ω6-PUFA	205.2	216.0

Table 2. Diet formulations of the two feeds fed to shi drum, g kg⁻¹.

Raw materials	DIET A (450/160)	DIET B (480/120)
Krill meal	27.2	27.1
Squid meal	27.2	27.1
Fish meal	326.0	340.5
Fish oil	122.2	81.6
Maize Gluten 60	163.0	162.3
Premix	3.30	3.2
Soya HP48, Non GMO	163.0	162.3
Vitamin C-35	5.4	5.4
Wheat	82.3	82.3
Wheat Gluten	80.5	108.2

Table 3. Sensory terms (descriptors) that were used for the shi drum Check-all-that-apply (CATA) sensory test.

Aroma	Flavour	Taste	Texture	Aftertaste
Boiled potato	Olive oil	Sweet	Fatty	Bitter
Butter	Metallic	Salty	Dry
Seaweed/iodine	Fish oil	Sour	Hard
Fishmeal	Butter	Bitter	Cohesive
Fish oil	Hay		Fibrous
Grass	Seafood		Soft
Cooked shrimp	Fatty		Elastic
Olive oil	Neutral		Sticky
	Fish oil		Juicy
	Spicy

Table 4. Somatic indexes, yields of shi drum (n = 27) and fillet proximate composition (n = 6) belonging to the two dietary groups.

	Group Α	Group Β
Body weight, g	575.8 ± 155.6	631.1 ± 149.9
Condition index	1.44 ± 0.28	1.32 ± 0.23
Dressing yield, % body weight	92.6 ± 4.39	92.1 ± 1.52
Visceral fat, % of bw	0.23 ± 0.20	0.24 ± 0.24
Peritoneal fat, % of bw	0.84 ± 0.46	0.90 ± 0.51
Hepatosomatic index (HSI	1.43 ± 0.28^b	1.26 ± 0.25^a
Gonadosomatic index (GSI)	0.54 ± 0.45	0.72 ± 0.80
Filleting yield, % of bw	32.6 ± 1.50	31.5 ± 3.73
Moisture, g kg^−1	750.0 ± 7.50	749.0 ± 8.90
Fat, g kg^−1	35.1 ± 4.10	39.3 ± 5.90
Protein, g kg^−1	199.0 ± 3.00	201.0 ± 1.50
Ash, g kg^−1	13.3 ± 0.10	13.4 ± 0.10

Values are given as mean ± standard deviation. Statistically significant differences (p < .05) are denoted by different letters (a,b).

Table 5. Fatty acid composition (in g kg⁻¹ fillet) of the two shi drum dietary groups (n = 6).

	Group Α	Group Β
14:0	0.95 ± 0.14	1.07 ± 0.10
15:0	0.10 ± 0.01	0.11 ± 0.01
16:0	5.59 ± 0.44^a	6.75 ± 0.22^b
16:1ω-7	0.10 ± 0.00^a	0.14 ± 0.02^b
16:1ω-9	1.29 ± 0.13^a	1.56 ± 0.15^b
16:3ω-3	0.14 ± 0.02	0.15 ± 0.03
17:0	0.10 ± 0.01	0.11 ± 0.02
17:1ω-9	0.12 ± 0.03	0.12 ± 0.01
18:0	1.26 ± 0.05^a	1.45 ± 0.02^b
18:1ω-9	11.01 ± 0.04	13.04 ± 1.78
18:1ω-7	1.33 ± 0.21	1.19 ± 0.11
18:2ω-6	6.22 ± 0.32	7.13 ± 1.00
18:3ω-3	1.09 ± 0.10	1.21 ± 0.17
20:1ω-9	0.89 ± 0.11	0.94 ± 0.15
20:2ω-9	0.24 ± 0.03	0.26 ± 0.04
20:4ω-6	0.31 ± 0.01	0.29 ± 0.02
20:3ω-3	0.10 ± 0.01	0.07 ± 0.01
20:4ω-3	0.22 ± 0.01	0.24 ± 0.02
20:5ω-3	1.33 ± 0.09	1.41 ± 0.15
22:0	0.39 ± 0.04	0.39 ± 0.07
22:1ω-9	0.17 ± 0.01	0.17 ± 0.02
22:5ω-3	0.68 ± 0.11	0.72 ± 0.03
22:6ω-3	2.90 ± 0.23	2.66 ± 0.32
SFA	8.40 ± 0.71^a	9.88 ± 0.41^b
MUFA	16.3 ± 1.02	18.7 ± 2.43
ω3-PUFA	6.48 ± 0.54	6.49 ± 0.75
ω6-PUFA	6.54 ± 0.32	7.43 ± 1.03

Statistically significant differences (p < .05) are denoted by different letters (a,b).

Table 6. Fillet volatile compounds and volatile compound classes, expressed as μg kg⁻¹ fresh tissue weight, of the two shi drum dietary groups ± standard deviation (n = 6).

Compound	Rt, min	Charact. Ions, m/z	Group A	Group B
2-Chloro-2-methyl- Butane	2.501	77,66,55	0.98 ± 0.17	0.91 ± 0.09
3-Methyl-2-Butanone	2.604	43,86	2.85 ± 0.49^b	0.28 ± 0.17^a
Propanoic acid	2.635	45,74	0.16 ± 0.11^b	tr. ^a
1-Penten-3ol	2.708	57,41,39	0.65 ± 0.07^b	0.47 ± 0.10^a
3-Penten-2ol	2.744	71,43,41	0.42 ± 0.10	0.35 ± 012
2,3-Pentanedione	2.903	43,57,100	0.28 ± 0.04	0.21 ± 0.04
2-Ethyl-furan	2.836	81, 53,110	0.21 ± 0.05	0.18 ± 0.03
3-Hydroxy-2-butanone	3.097	45,43,88	6.13 ± 0.08^b	4.58 ± 0.22^a
cis-2-Pentenal	3.760	55,83,84	0.14 ± 0.01	0.17 ± 0.08
Toluene	3.821	91,92,65	1.09 ± 0.35	0.88 ± 0.28
Octane	4.448	43,85,57	0.12 ± 0.01	0.13 ± 0.02
Hexanal	4.606	44,56,41	1.16 ± 0.22^b	0.09 ± 0.11^a
3-Pentanol	4.655	59,107,45	0.12 ± 0.01	0.09 ± 0.01
2-hexanol	4.740	45,41	0.12 ± 0.01	0.13 ± 0.01
p-Xylene	6.522	91,106,105	1.14 ± 0.06^b	0.84 ± 0.07^a
o-Xylene	9.345	91,106,105	0.02 ± 0.00^b	0.01 ± 0.00^a
2-Heptanone	7.520	43,58,71	0.09 ± 0.00^b	0.06 ± 0.00^a
1,2,3,4,5-pentamethyl-cyclopentane	7.544	84,57,69	0.30 ± 0.10	0.24 ± 0.08
trans-4-heptenal	7.824	41,55,68	0.12 ± 0.02^b	0.05 ± 0.00^a
Heptanal	7.897	70,44,43	0.31 ± 0.05^b	0.18 ± 0.01^a
1,2,3,4,5-Pentamethyl-cyclopentene	8.451	123,81,138	0.61 ± 0.15^b	0.47 ± 0.08^a
3,3,5,5-Tetramethyl-cyclopentene	9.448	106,67,81	0.40 ± 0.05	0.38 ± 0.08
4-Methyl-1-heptene	10.014	70,43,41	0.33 ± 0.11	0.32 ± 0.05
2-Furan-carboxaldehyde	10.051	110,109,53	0.53 ± 0.18^b	0.25 ± 0.10^a
Benzaldehyde	10.458	106,105,77	0.20 ± 0.06^a	0.34 ± 0.04^b
2,3-octanedione	12.034	43,71,99	0.041 ± 0.000^a	0.018 ± 0.000^b
Octanal	12.947	43,41,57	0.14 ± 0.00^a	0.16 ± 0.01^b
trans,trans-2,4-Heptadienal	13.394	81,110,53	0.10 ± 0.02	0.07 ± 0.04
Benzeneacetaldehyde	15.149	91,92,120	0.39 ± 0.06^b	0.18 ± 0.05^a
Unknown hydrocarbon	16.116	43,57,71	tr.^a	0.21 ± 0.00^b
2-E-octenal	16.183	41,55,70	0.002 ± 0.000^a	0.012 ± 0.000^b
Nonanal	19.134	57,41,56	0.53 ± 0.10^a	0.64 ± 0.03^b
2-E-nonenal	22.705	41,43,83	0.004 ± 0.000^a	0.010 ± 0.000^b
1-Dodecene	24.834	41,43,83	0.26 ± 0.10	0.22 ± 0.05
Dodecane	25.394	57,43,71	0.09 ± 0.00^b	tr.^a
Decanal	25.746	57,43,41	0.19 ± 0.10^a	0.50 ± 0.13^b
1-Tetradecene	34.604	55,41,43	0.23 ± 0.05	0.21 ± 0.02
Tetradecane	36.151	57,43,71	0.09 ± 0.03	0.12 ± 0.10
2,6 Bis (1,1,dimethylethyl)-cyclohexadiene-1,4dione	34.945	177,220,135	0.19 ± 0.07	0.11 ± 0.13
Unknown	36.539	161,203,218	1.25 ± 0.27^b	0.26 ± 0.14^a
Unknown	37.701	57,135,234	0.21 ± 0.12	0.15 ± 0.18
Unknown H/C	38.723	71,43,56	0.40 ± 0. 32^a	1.91 ± 0.38^b
Heptadecane	40.274	57,43,71	1.51 ± 0.81^a	2.77 ± 0.49^b
Octadecane	41.673	57,71,43	014 ± 0.30	0.28 ± 0.19
Hexadecanal	41.910	57,43,82	0.08 ± 0.05^a	0.39 ± 0.19^b
Unknown aldehyde	42.227	69,41,81	0.19 ± 0.15	0.09 ± 0.10
9-Nonadecene	42.671	55,83,97	0.06 ± 0.01^a	0.14 ± 0.05^b
Nonadecane	42.963	57,71,43	0.13 ± 0.07^a	0.26 ± 0.08^b
13 Octadecenal	44.058	55,69,67	0.08 ± 0.08^a	0.31 ± 0.12^b
Unknown aldehyde	44.307	57,82,96	0.05 ± 0.08^a	0.27 ± 0.10^b
Unknown H/C	45.062	57, 43, 71	0.22 ± 0.14	0.25 ± 0. 07
Unknown H/C	45.317	57, 71,43	0.26 ± 0.20	0.14 ± 0.32
Unknown H/C	46.771	57,43,41	0.40 ± 0.11^b	0.18 ± 0.10^a
Squalene	46.893	69,81,41	0.07 ± 0.02^a	0.37 ± 0.11^b
Alcohols			1.39 ± 0.21	1.10 ± 0.35
Aldehydes			4.67 ± 0.13^b	4.22 ± 0.29^a
Ketones			9.91 ± 2.17^b	5.61 ± 1.79^a
Furans			0.29 ± 0.06	0.26 ± 0.08
Amines			0.29 ± 0.05	0.23 ± 0.04
Pyrazines			0.01 ± 0.01	0.01 ± 0.01
Pyrrols			tr.^a	0.06 ± 0.03^b
Esters			0.17 ± 0.01^a	0.25 ± 0.03^b
Hydrocarbons			11.1 ± 3.34	11.5 ± 1.11
Thio-compounds			0.01 ± 0.01	0.01 ± 0.01
Acids			0.16 ± 0.05^b	tr.^a
Total			31.1 ± 4.38	27.9 ± 2.34

The retention times (Rt) and characteristic ions for each volatile compound are also provided. Statistically significant differences (p < .05) are denoted by different letters (a,b). tr: traces (< 0.01 μg kg⁻¹ fresh weight).

Table 7. Frequency of positive CATA answers, for descriptive terms in which the two shi drum groups differed significantly (p < .05) or showed a tendency for difference (p < .10), along with their level of significance; the CATA test was performed using 36 subjects.

Descriptive terms	PositiveanswersGroup Α	PositiveanswersGroup Β	Level ofsignificance
Seaweed/iodine aroma	0	4	p=.046
Fish oil aroma	10	2	p=.021
Seafood flavour	0	6	p=.014
Hay flavour	4	0	p=.046
Sweet taste	6	14	p=.021
Elastic texture	8	2	p=.014
Hard texture	4	0	p=.046
Dry texture	20	12	p=.074
Bitter aftertaste	8	2	p=.014