Fish welfare: Current issues in aquaculture

Pattern recognition

Colour is the first quality attribute of food evaluated by consumers, and is therefore an important component of food quality relevant to market acceptance. Rapid and objective measurement of food colour is required in quality control for the commercial grading of products. Computer vision is a promising technique currently investigated for food colour measurement, especially with the ability of providing a detailed characterization of colour uniformity at pixel-based level. This paper reviews the fundamentals and applications of computer vision for food colour measurement. Introduction of colour space and traditional colour measurements is also given. At last, advantages and disadvantages of computer vision for colour measurement are analyzed and its future trends are proposed.

Colour measurements by computer vision for food quality control – A review

Mobile single-sided NMR

Modification of the Plasma Cortisol Response to Stress in Rainbow Trout by Selective Breeding

Salmon slaughtered by standard routines (control) or stressed by confinement for 10 min before stunning and then stored at 0.4 or 3.3°C for 9 days were compared. Handling stress led to lower muscle phosphocreatine (p<0.001), adenosine-5′-triphosphate (p<0.05) and shorter pre-rigor period. Storage temperature affected external quality index, white muscle pH and K-value (degradation products of ATP). Stress produced a softer fillet (p<0.001). A lower breaking strength (p<0.01) was found in fish stored at 0.4°C. Sensory tests distinguished the control/stress groups within the 0.4°C chilling regime and the 0.4°C/3.3°C chilling groups within the control regime. Stress caused a lower score for texture (p<0.05) both at 0.4 and 3.3°C and for odor at 3.3°C in a descriptive sensory test. No detectable effects of stress or storage temperature were found on flavor or color.

Handling Stress and Storage Temperature Affect Meat Quality of Farmed-raised Atlantic Salmon (Salmo Salar)

The changes in skin and fillet color of anesthetized and exhausted Atlantic salmon were determined immediately after killing, during rigor mortis, and after ice storage for 7 d. Skin color (CIE L*, a*, b*, and related values) was determined by a Minolta Chroma Meter. Roche SalmoFan Lineal and Roche Color Card values were determined by a computer vision method and a sensory panel. Before color assessment, the stress levels of the 2 fish groups were characterized in terms of white muscle parameters (pH, rigor mortis, and core temperature). The results showed that perimortem handling stress initially significantly affected several color parameters of skin and fillets. Significant transient fillet color changes also occurred in the prerigor phase and during the development of rigor mortis. Our results suggested that fillet color was affected by postmortem glycolysis (pH drop, particularly in anesthetized fillets), then by onset and development of rigor mortis. The color change patterns during storage were different for the 2 groups of fish. The computer vision method was considered suitable for automated (online) quality control and grading of salmonid fillets according to color.

Atlantic salmon skin and fillet color changes effected by perimortem handling stress, rigor mortis, and ice storage.

Influence of brine concentration on Atlantic salmon fillet salting

A comparative study of brine salting of Atlantic cod (Gadus morhua) and Atlantic salmon (Salmo salar)

The effect of different Atlantic salmon raw materials (prerigor, postrigor and frozen/thawed) on water mobility and salt uptake after brine salting was investigated by using LF 1H NMR T2 relaxation,1H and 23Na MRI and light microscopy. Distributed exponential analysis of the T2 relaxation data revealed two main water pools in all raw materials, T21 and T22, with relaxation times in the range of 20-100 ms and 100-300 ms, respectively. Raw material differences were reflected in the T2 relaxation data. Light microscopy demonstrated structural differences between unsalted and salted raw materials. For prerigor fillets, salting induced a decrease in T21 population coupled with a more open microstructure compared to unsalted fillets, whereas for frozen/thawed fillets, an increase in T21 population coupled with salt-induced swelling of myofibers was observed. The result implies that the T21 population was directly affected by the density of the muscle myofiber lattice. MR imaging revealed significant differences in salt uptake between raw materials, prerigor salted fillets gained least salt (1.3-1.6% NaCl), whereas the frozen/thawed fillets gained most salt (2.7-2.9% NaCl), and obtained the most even salt distribution due to the more open microstructure. This study demonstrates the advantage of LF NMR T2 relaxation and 1H and 23Na MRI as effective tools for understanding of the relationship between the microstructure of fish muscle, its water mobility and its salt uptake.

Water and salt distribution in Atlantic salmon (Salmo salar) studied by low-field 1H NMR, 1H and 23Na MRI and light microscopy: effects of raw material quality and brine salting.

Ulf Erikson

Papers

Handling Stress and Storage Temperature Affect Meat Quality of Farmed-raised Atlantic Salmon (Salmo Salar)

Atlantic salmon skin and fillet color changes effected by perimortem handling stress, rigor mortis, and ice storage.

Influence of brine concentration on Atlantic salmon fillet salting

A comparative study of brine salting of Atlantic cod (Gadus morhua) and Atlantic salmon (Salmo salar)

Water and salt distribution in Atlantic salmon (Salmo salar) studied by low-field 1H NMR, 1H and 23Na MRI and light microscopy: effects of raw material quality and brine salting.