Sensory Properties and Chemical Composition of Fish Solubles Obtained from Upcycling of Fish Filleting Side Streams

Figures & data

Table 1. Attributes and description of the sensory attributes evaluated by the sensory panel. Descriptions are based on the Norwegian standard NS-ISO 5492.

Attribute	Description
Smells
Total intensity of smell	The intensity of all different smell present in the sample
Sourness smell	Organoleptic attribute of pure substances or mixtures which produces the sour sensation
Trimethylamine smell	The smell of TMA, ammonia, and a sharp sensation
Pungent smell	Describes a product causing a sharp sensation of the nasal mucous membrane
Sour/Fermented smell	A fermented and unpleasant sour smell related to a complex sensation generally due to the presence of organic acids.
Fish smell	The smell of white fish (i.e. cod, pollock, haddock, redfish)
Process smell	The smell related to a burned, mechanical and exhaust like smell
Rancid smell	The intensity of all rancid smells (i.e. grass, hay, stearin, paint)
Tastes and flavor
Total flavor intensity	The intensity of all different flavors presents in the sample
Sour flavor	Organoleptic attribute of pure substances or mixtures which produces the sour sensation
Sweet taste	Describes the basic taste produced by diluted aqueous solutions of various substances such as sucrose
Salty taste	Describes the basic taste produced by diluted aqueous solutions of various substances such as sodium chloride
Acid taste	Describes the basic taste produced by diluted aqueous solutions of most acid substances (i.e citric acid)
Bitter taste	Describes the basic taste produced by diluted aqueous solutions of various substances such as quinine and caffeine
Umami taste	Describes the basic taste of umami
Trimethylamine flavor	The taste of TMA, ammonia and a sharp sensation
Pungent flavor	Describes a product causing a sharp sensation of the buccal mucous membrane
Sour/fermented flavor	A fermented and unpleasant sour flavor related to a complex sensation generally due to the presence of organic acids.
Fish flavor	The flavor of white fish (i.e. cod, pollock, haddock, redfish)
Process flavor	The flavor related to a burned, mechanical and exhaust like smell
Rancid flavor	The intensity of all rancid flavors (i.e. grass, hay, stearin, paint)
Fullness	Mechanical texture property related to the flow resistance, a rich sensation of the sample in the mouth
Astringent	A complex feeling, followed by contractions, dryness sensation, puckering of the skin or mucous membranes in the mouth
Aftertaste	Aftertaste after ½ minute without rinsing the mouth

Table 2. Chemical composition (g/kg dry matter), NaCl relative to ash (%), peptide size distribution (% of peptides) of fish solubles based on trimmings (Trim), heads, backbones, skin (HBS) and viscera from cod, haddock, saithe, and golden redfish.

	Cod			Haddock			Saithe			Redfish
	Trim	HBS	Viscera	Trim	HBS	Viscera	Trim	HBS	Viscera	Trim	HBS	Viscera
Protein (N × 5.3)^a	685	489	574	624	489	594	566	525	642	674	541	563
Ash	308	294	207	333	294	167	320	316	123	381	250	176
NaCl	54	194	107	75	200	71	52	189	54	43	185	97
NaCl/Ash	18%	68%	52%	23%	68%	43%	16%	60%	44%	11%	74%	55%
Peptide distribution
>20 kDa	9.6	10.1	2.6	4.4	8.7	0.6	1.1	10.5	0.3	0.4	15.9	0.4
20–15 kDa	1.6	2.4	1.0	1.2	1.9	0.5	0.5	3.3	0.3	0.2	4.5	0.4
15–10 kDa	1.8	3.1	2.3	2.1	2.2	2.0	0.7	4.1	0.8	0.3	5.8	1.2
10–8 kDa	0.8	1.6	2.0	1.6	1.1	2.2	0.4	2.0	0.8	0.2	3.7	1.0
8–6 kDa	0.8	1.7	3.8	2.4	1.3	3.9	0.5	2.1	1.8	0.3	4.1	1.8
6–4 kDa	0.7	1.7	6.8	3.1	1.4	7.2	0.6	2.3	4.8	0.4	4.1	3.5
4–2 kDa	0.6	2.1	10.7	4.3	1.7	14.4	0.7	2.5	12.0	0.6	4.3	7.3
2–1 kDa	0.3	1.2	7.4	2.9	0.8	12.1	0.4	1.3	13.4	0.4	2.3	6.6
1–0.5 kDa	0.4	1.0	4.9	2.5	0.8	8.6	0.6	0.9	10.9	0.4	1.5	5.7
0.5–0.2 kDa	17.6	3.0	5.4	16.4	5.6	7.0	19.2	3.1	9.0	4.1	2.7	9.1
<0.2 kDa	65.7	72.2	53.2	58.9	74.5	41.5	75.2	67.9	45.9	92.7	51.1	63.0

^aBased on Steinsholm et al. (2020).

Table 3. Levels of free amino acids and dipeptides (g/kg dry matter) in fish solubles based on trimmings (Trim), heads, backbones, skin (HBS), and viscera from cod, haddock, saithe, and golden redfish.

	Cod			Haddock			Saithe			Redfish
	Trim	HBS	Viscera	Trim	HBS	Viscera	Trim	HBS	Viscera	Trim	HBS	Viscera
Protein-AA
Aspartic acid	<1	<1	10	<1	<1	12	<1	5	18	<1	5	12
Glutamic acid	15	12	24	8	12	17	16	16	19	5	5	12
Hydroksyproline	<1	<1	<1	<1	<1	<1	<1	<1	<1	<1	<1	<1
Serine	4	6	10	4	6	12	4	5	16	5	5	12
Asparagine	<1	<1	<1	<1	<1	2	<1	<1	<1	<1	<1	3
Glycine	8	6	7	8	6	10	12	11	12	10	10	9
Glutamine	8	12	72	8	12	36	8	11	51	<1	10	38
Histidine	<1	<1	<1	<1	<1	5	<1	<1	4	<1	<1	6
Threonine	4	06	7	4	6	12	4	5	14	<1	5	9
Alanine	12	12	14	8	12	17	12	11	21	5	10	18
Arginine	<1	<1	14	<1	6	21	<1	<1	21	<1	5	15
Proline	4	<1	7	<1	<1	7	04	5	9	5	5	9
Tyrosine	<1	<1	7	<1	<1	10	<1	<1	12	<1	<1	9
Valine	<1	<1	7	4	6	12	4	5	14	<1	5	12
Methionine	<1	<1	7	4	<1	10	<1	<1	12	<1	<1	9
Cysteine	<1	<1	<1	<1	<1	<1	<1	<1	<1	<1	<1	<1
Isoleucine	<1	<1	7	<1	<1	10	<1	<1	12	<1	<1	12
Leucine	<1	6	14	4	6	24	4	5	28	<1	5	21
Phenylalanine	<1	<1	7	<1	<1	10	<1	<1	14	<1	<1	9
Tryptophan	<1	<1	<1	<1	<1	2	<1	<1	4	<1	<1	3
Lysine	4	6	17	4	6	19	4	5	25	14	5	21
Sum free protein-AA	58	65	231	58	76	245	72	84	305	43	75	235
Non-protein AA
Creatinine*	8	<1	<1	8	<1	<1	4	<1	<1	10	<1	<1
β-alanine	8	6	3	4	6	<1	12	16	2	<1	<1	<1
Taurine	62	71	86	33	71	52	52	74	40	100	85	68
4-aminobutanoic acid	<1	<1	<1	<1	<1	<1	<1	<1	<1	<1	<1	<1
Citrulline	<1	<1	<1	<1	<1	2	<1	<1	2	<1	<1	<1
Carnosine*	<1	<1	<1	<1	<1	<1	<1	<1	<1	<1	<1	3
L-Ornithine	<1	<1	<1	<1	<1	<1	<1	<1	2	<1	<1	3
Anserine*	69	<1	<1	92	6	2	56	<1	<1	<1	<1	3
Sum non-protein AA	146	76	90	138	82	57	124	89	46	110	85	77

*dipeptides.

Table 4. Mean sensory intensity values of smells in fish solubles based on trimmings, heads, backbones, skin (HBS) and viscera from cod, haddock, saithe, and redfish. Different letters indicate statistical difference (p < .05) within each attribute based two-way mixed factorial model and Tukey’s post hoc test.

		Total smell	Sourness	TMA	Pungent	Fermented	Fish	Process	Rancid
Cod	Trimmings	4.5^e	1.9^ab	2.6^d	3.6^de	2.2^c	2.6^d	1.4^b	1.1^c
	HBS	6.5^abc	1.1^c	5.3^a	6.2^abc	4.2^ab	5.1^ab	2.2^ab	2.7^bc
	Viscera	6.8^ab	1.1^c	4.9^ab	6.7^a	5.1^a	4.1^abcd	2.0^ab	3.0^bc
Haddock	Trimmings	5.1^de	2.0^a	2.9^cd	3.3^e	2.2^c	2.9^d	1.5^b	1.2^c
	HBS	6.0^abcd	1.3^bc	4.6^ab	5.4^abcd	3.6^abc	3.9^abcd	1.9^ab	1.6^bc
	Viscera	6.6^abc	1.2^c	4.5^abc	5.9^abc	3.5^abc	3.9^abcd	2.5^ab	3.5^b
Saithe	Trimmings	5.4^cde	1.4^abc	3.4^bcd	4.4^cde	2.8^bc	3.1^cd	2.1^ab	1.3^c
	HBS	5.6^bcde	1.3^bc	3.9^abcd	5.2^abcde	3.6^abc	3.4^bcd	1.8^ab	1.5^c
	Viscera	6.1^abcd	1.1^c	4.2^abcd	5.1^abcde	2.6^bc	4.1^abcd	2.8^ab	2.9^bc
Redfish	Trimmings	6.9^a	1.0^c	4.2^abcd	6.7^ab	3.1^bc	5.4^a	3.1^a	5.9^a
	HBS	6.1^abcd	1.4^abc	4.6^ab	5.5^abc	2.8^bc	4.7^abc	1.8^ab	2.3^bc
	Viscera	5.7^abcde	1.3^bc	4.2^abcd	4.8^bcde	3.2^bc	4.0^abcd	2.0^ab	1.9^bc
p-value		<.001	<.001	<.001	<.001	<.001	<.001	0.017	<.001

Table 5. Mean sensory intensity values of taste and flavor in fish solubles based on trimmings, heads, backbones, skin (HBS) and viscera from cod, haddock, saithe, and redfish. Different letters indicate statistical difference (p < 0.05) within each attribute based two-way mixed factorial model and Tukey’s post hoc test.

		Total flavor intensity	Sour	Sweet	Salty	Acid	Bitter	Umami	TMA	Pungent	Sour/ Fermented	Fish	Process	Rancid	Fullness	Astringent	Aftertaste
Cod	Trimmings	5.1^c	1.8^abc	3.1	3.7^bc	2.5	3.3^c	4.5^ab	3.1^b	4.1^bc	1.6^c	3.2^b	1.3	1.2^c	4.2^a	3.4^bc	5.2
	HBS	6.3^ab	1.2^bc	2.9	4.4^ab	2.5	4.0^bc	3.3^c	5.1^a	6.0^ab	3.4^ab	4.8^ab	1.8	2.5^bc	4.0^ab	3.5^abc	6.0
	Viscera	6.9^a	1.0^c	3.0	3.4^c	2.7	5.6^a	3.6^bc	5.2^a	6.4^a	4.2^a	4.8^ab	2.5	2.7^bc	3.8^ab	4.2^ab	5.9
Haddock	Trimmings	5.6^bc	2.1^a	2.9	3.7^bc	2.8	3.7^c	4.6^a	3.3^b	3.5^c	2.0^bc	3.9^ab	1.4	1.2^c	4.1^ab	3.5^abc	5.2
	HBS	6.2^abc	1.2^bc	2.8	4.7^a	2.6	3.8^bc	3.7^abc	4.2^ab	5.5^ab	2.8^abc	3.7^b	2.2	1.6^bc	4.1^ab	3.1^c	5.4
	Viscera	6.2^abc	1.3^bc	2.8	3.4^c	2.6	4.4^abc	4.1^abc	4.7^ab	5.3^abc	2.9^abc	4.8^ab	1.9	2.8^bc	3.7^ab	3.8^abc	5.7
Saithe	Trimmings	5.5^bc	1.5^abc	2.8	3.3^c	2.4	3.4^c	4.0^abc	3.3^b	4.3^bc	2.1^bc	3.3^b	1.7	1.5^bc	3.7^ab	3.4^bc	5.3
	HBS	6.0^abc	1.2^bc	2.7	3.9^abc	2.4	3.6^c	3.4^c	4.5^ab	5.7^ab	3.1^abc	3.9^ab	1.6	1.6^bc	3.7^ab	3.4^bc	5.4
	Viscera	6.2^abc	1.4^bc	2.7	3.2^c	2.8	5.1^ab	3.5^bc	4.3^ab	4.8^abc	2.1^bc	4.3^ab	2.1	2.1^bc	3.4^b	4.4^a	5.6
Redfish	Trimmings	6.6^ab	1.1^c	2.8	3.6^bc	2.8	3.9^bc	3.8^abc	4.6^ab	6.4^a	2.6^abc	5.5^a	2.5	4.9^a	3.8^ab	3.9^abc	5.8
	HBS	5.7^bc	1.4^bc	2.9	4.1^abc	2.3	3.6^c	3.9^abc	4.2^ab	4.9^abc	2.3^bc	4.3^ab	1.4	2.2^bc	3.8^ab	3.4^abc	5.4
	Viscera	6.0^abc	1.4^bc	2.7	3.4^c	2.8	4.7^abc	3.6^bc	4.2^ab	4.6^abc	2.3^bc	4.2^ab	1.6	1.5^bc	3.6^ab	3.9^abc	5.3
p-value		<.001	<.001	.8	<.001	.004	<.001	<.001	<.001	<.001	<.001	<.001	.03	<.001	.02	.001	.2

Figure 1. Mean intensity of smell sensory attributes for cod, haddock, saithe, and golden redfish (a) and trimmings, head-backbone-skin (HBS) and viscera (b). Different letters for each parameter within each attribute indicate significant differences (p < 0.05) based on ANOVA and Tukey’s post hoc test.

Figure 2. Mean intensity of taste and flavour sensory attributes for cod, haddock, saithe, and golden redfish (a) and trimmings, head-backbone-skin (HBS) and viscera (b). Different letters for each parameter within each attribute indicate significant differences (p < 0.05) based on ANOVA and Tukey’s post hoc test.

Figure 3. (a) Principal component analysis loading plot based on NaCl (black; Table 2), peptide molecular weight distribution (red; Table 2) distribution of free amino acids (blue; Table 3) and sensory attributes (green; Tables 4 and 5). The two ellipses represent 50% and 100% of explained variance. (b) Principal component analysis score plot showing similarities and differences between the fish solubles based on cod, haddock, saithe and redfish trimmings, head-backbone-skin (HBS), and viscera.

Steinsholm S, Oterhals Å, Underhaug J, Måge I, Malmendal A, Aspevik T. 2020. Sensory assessment of fish and chicken protein hydrolysates. Evaluation of NMR metabolomics profiling as a new prediction tool. J Agr Food Chem. 68(12):3881–90.

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