A practical quality index method (QIM) developed for aquacultured rainbow trout (Oncorhynchus mykiss)

Figures & data

Table 1. The QIM scheme developed for rainbow trout (Oncorhynchus mykiss) by ^[29].

	Quality parameters	Points
Skin	Color/appearance	0–2
	Mucus	0–1
	Odor	0–2
	Texture	0–2
Eyes	Pupils	0–2
	Form	0–2
Gills	Color/appearance	0–2
	Mucus	0–2
	Odor	0–3
Abdomen	Blood in abdomen	0–1
	Odor	0–2
Quality Index Total		0–21

Table 2. QIM scheme developed for Atlantic salmon (Salmo salar) by ^[13].

Quality parameters	Description	Points
Skin
Color/appearance	Pearl-shiny all over the skin	0
	The head is still pear-shiny, but the rest less perhaps yellow	1
Mucus	Clear and not clotted	0
	Milky and clotted	1
	Yellow and clotted	2
Odor	Fresh seaweed, cucumber	0
	Neutral to metal, dry grass, corn	1
	Sour	2
	Rotten	3
Eyes
Pupils	Clear and black, metal shiny	0
	Dark, gray	1
	Mat, grAy	2
Form	Flat	0
	Little sunken	1
	Sunken	2
Abdomen
Blood in abdomen	Blood light red/not present	0
	Blood more brown	1
Odor	Neutral	0
	Corn	1
	Sour	2
	Rotten/rotten kale	3
Gills
Color/appearance	Red/dark brown	0
	Light red/brown	1
	Gray-brown, gray, green	2
Mucus	Transparent	0
	Yellow clotted	1
	Brown	2
Odor	Fresh, seaweed	0
	Metal	1
	Sour	2
	Rotten	3
Texture
Elasticity	Finger mark disappears immediately	0
	Finger leaves mark over 3 s	1
Quality Index Total 22

Table 3. Final developed QIM scheme for whole (ungutted) rainbow trout samples.

Parameter	Changes	Description	Points
Skin	Brightness	Bright	0
		Faded	1
		Mate	2
Mucus	Clarity	Clear	0
		White/high viscosity	1
		Gray/blackish/low viscosity	2
Elasticity	Fingerprints	Elastic	0
		Fingerprints < 3 s	1
		Fingerprints ≥3 s	2
Belly	Softness	Rough	0
		Started to be soft	1
		Soft	2
	Color	White	0
		Locally yellow/brown	1
Odor of whole fish	Fresh/rotten	Fresh/characteristic	0
		Neutral	1
		Soil/metallic/rotten	2
Eyes	Clarity	Clear	0
		Locally opaque	1
		Mate	2
	Shape	Convex	0
		Flat	1
		Concave	2
Gills	Color	Red/pinkish	0
		Mate/locally red	1
		Dark red/yellowish	2
	Odor	Characteristic/soil	0
		Neutral/metallic	1
		Rotten/metallic/sour	2
	Mucus	Clear/liquid	0
		Red/pinkish	1
		Dark red/dense/yellowish	2
Peritoneum	Status	Attached/firm	0
		Locally separated	1
		Separated	2
Inner organs	Status	Whole	0
		Locally fractured	1
		Liquid accumulation/fractured	2
	Odor	Characteristic/soil	0
		Metallic	1
		Rotten/sour/metallic	2
Fins	Status	Firm rays	0
		Locally fractured	1
		Fractured	2
Rigor mortis		In rigor	0
		Postrigor	1
Quality Index		Total	30

Table 4. Final developed QIM scheme for gutted rainbow trout samples.

Parameter	Changes	Description	Points
Skin	Brightness	Bright	0
		Faded	1
		Mate	2
Mucus	Clarity	Clear	0
		White/high viscosity	1
		Grey/blackish/low viscosity	2
Elasticity	Fingerprints	Elastic	0
		Fingerprints < 3 s	1
		Fingerprints ≥ 3 s	2
Odor of whole fish	Fresh/rotten	Fresh/characteristic	0
		Neutral	1
		Soil/metallic/rotten	2
Eyes	Clarity	Clear	0
		Locally opaque	1
		Mate	2
	Shape	Convex	0
		Flat	1
		Concave	2
Odor of peritoneum	Fresh/rotten	Characteristic/soil/fruity/neutral	0
		Slight metallic/sourish	1
Fins	Status	Firm rays	0
		Locally fractured	1
		Fractured	2
Quality Index		Total	15

Figure 1. QIM scores obtained from the draft scheme for whole rainbow trout.

Figure 2. QIM scores obtained from the draft scheme for gutted rainbow trout.

Figure 3. QIM scores obtained from the final scheme for whole rainbow trout.

Figure 4. QIM scores obtained from the final scheme for gutted rainbow trout.

Green-Petersen, D. M. B.; Sensory Quality of Seafood – in the Chain from Catch to Consumption (PhD Thesis). 2010, Copenhagen, Denmark: University of Denmark;.

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Sveinsdottir, K.; Hyldig, G.; Martinsdottir, E.; Jorgensen, B.; Kristbergsson, K. Quality Index Method (QIM) Scheme Developed for Farmed Atlantic Salmon (Salmo Salar). Food Quality Pref 2003, 14, 237–245. DOI:10.1016/S0950-3293(02)00081-2.

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