2. Material and methods
2.1. Preparation of samples
Surimi from a cold-water fish species (Alaska Pollock)
and a temperate-water species (Pacific Whiting) was used
to prepare crab sticks. Table 1 shows the technical characteristics
of the two types of surimi as supplied by their manufacturers.
Samples were prepared at a pilot plant of a
Spanish firm that produces surimi and surimi seafood.
The sticks studied contained 55% surimi, 25–33% water,
2% egg white, 1.3% salt, ca. 1% vegetable oil and flavourings,
and 7%, 11% or 15% starch.
In order to avoid damaging the blender, frozen surimi
samples were allowed to thaw to a temperature never
exceeding 0 C. To this end, product blocks were stored
in a refrigerator overnight, subjected to an air-stream at
room temperature or placed on trays through which water
at 30 C was circulated. Then, the surimi was blended with
the ingredients in the previous proportions, the starch
being previously suspended in water to facilitate hydration.
The temperature was kept below 10 C throughout in order
to avoid denaturation of proteins and facilitate gel formation;
this was no problem in the test enclosure, which was a
factory room conditioned at ca. 8 C.
The next step involved extruding the raw surimi-ingredient
paste in the cooking roller, which was heated at 95–
98 C in order to ensure formation of a thermal gel. In this
way, a solid sheet 25 cm wide 1.2–1.5 cm thick was
obtained; immediately, the conveyor belt carrying the
extruded sheets entered a water vapour-saturated atmosphere
to prevent the paste from drying out.
Then, the sheets were allowed to cool to room temperature
and slit lengthwise by means of rollers, the bottom
portion being fringed as a result. Next, a mechanical system
was used to coil the sheets about their shorter side –