Value added fish by-products - Nordic Innovation

Generally, the time dependent flow behaviour viscosity of the collected fish masses decreased
with temperature up to 70°C (Figure 3.3). The viscosity of the fillets was rather stable with
increasing temperature, up to approximately 50°C, but between 50-85°C the viscosity
increased. If these results are viewed with regard to known temperatures linked to protein
denaturation, than it can been seen that viscosity decreased around 45°C. Thorarinsdottir et al.
(2002) found that cod muscle proteins denatured in the temperature range 39-76°C according
to measurements with differential scanning calorimetry (DSC). Other studies have also shown
reduction in solubility at temperature below 30°C.
Figure 3.3. Time-dependent flow behaviour viscosity measured with Brabender® Viscograph E where samples were
heated from 30°C to 85°C. Measurements were performed on collected material from skinning machine (0.5-2 mm)
and from filleting machine (1mm). Minced fillet was also measured
The amount of collected material is highly variable, depending on the type of fish, quality,
time of year etc. The properties of the collected fish mass are also variable depending on
which part of the fish it comes from (e.g. from loin or tail). Mass balance on dry matter
collected from fresh versus thawed material showed that coarser sieve is needed for the
thawed material and more material is collected. The freezing of material before processing
had no negative effects on the physicochemical properties of the protein from the processing
water. This occurred in spite of lower solubility of the protein in processing water from
thawed material compared with processing water from fresh material. The fish mass collected
from processing water of thawed material had higher water holding capacity compared to
processing water of fresh material.
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Fillet
Skin. 0.5mm
Skin. 1 mm
Skin. 2mm
Filleting 1mm