Note: Descriptions are shown in the official language in which they were submitted.
X253387
The invention relates to the use of an edible flat collagen sheet in
the production of smoked foodstuffs, especially smoked fish products.
In the preparation of smoked foodstuffs, especially fish products,
which consist of relatively large portions or pieces of a whole fish, such as,
for example, salmon sides, there arises the problem that the cut surfaces
along which the pieces have been separated or sub-divided from the whole, must
be protected from contamination by dirt, dust and bacteria. These cut
surfaces are as a rule the cut surfaces of muscle, that is to say, the flesh
and muscle fibres are exposed without the protection of the natural skin. In
addition, when cutting through muscle tissue, the result is frequently a
rather rough cut surface from which the cut muscle fibres project, and after
drying and smoking this looks unattractive. This rough cut surface
disadvantage occurs especially in the production of smoked salmon sides. In
the production of smoked salmon sides, the salmons are halved in the
longitudinal direction, boned, mildly salted and smoked. Subsequently, the
halves are cut into slices or are vacuum-packed Whole. Hitherto, in order to
avoid the unattractive appearance of the rough cut surfaces from which the cut
muscle fibres project When producing smoked salmon sides, the cut surfaces
waro coverod, before being smoked, with so-called gold-beater's skin in order
Eo obEain a sealed surface again. Gold-beater's skins are obtained fCOm
bovine cenum, the so-called "Blind" from the outside of which a thin membrane
(Serosa) can be removed. For use in salmon smoking these gold-beater's skins,
which are supplied prQServed in salt, are washed thoroughly with slightly
chlorinated or ozonised water to remove the salt and unpleasant smell and
taste. They are then placed on the salmon halves, the surface is smoothed
with a knife and all the air bubbles underneath are removed. The overhanging
portion of the gold-beater's skin is wrapped around the skin side of the
ealm;on half and applied smoothly there. After smoking, the salmon sides ace
cut into slices and packed. They can thon be stored at from 0°C to
4°C for
approximately 4 weeks. Covering tho salmon silos with gold-beater's skins has
various shortcomings, however. The skins are of different sizes so that'tho
degree of utilization thereof depends very much on the skill of the worker.
In spite of careful preliminary treatment they often have an unpleasant
smell. Also, after storage in salt they still contain germinable spores of
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micro-organisms detrimental to the Foodstuffs and thus they impair the storage
quality of goods produced with them.
To solve the problems described shove - to cover cut muscle surfaces
for effective protection against contamination, to smooth surfaces that have
been roughened by cutting or boning operations, to reduce the adhesion to the
contents of the package of casings used only temporarily during preparation -
it is proposed in accordance with the invention that edible artificial flat
collagen sheets be used. These are made by transformation of natural collagen
raw material.
Such edible artificial flat collagen sheets are already known. They
are described, inter al , in DB-PS 642 922. Such collagen sheets may be
manufactured on a sheet-casting machine (D8-PS 842 825 and US-PS 2 747 226).
These collagen sheets are used for a wide variety of purposes. They are
frequently used, for example, as intermediates for the manufacture of surgical
sewing threads (US-PS 2 747 228 and US-PS 3 014 024). They ~Y also be use8
as a casing for foodstuffs (DE-PS 19 45 527) and also for wrapping meat
products (U5-PS 3 Q14 024). The collagen Can be pretreated in various ways
for adaptation to the desired use. For example, DS-PS 17 67 613 and 19 60 935
provide an enzyme treatment for the starting material in order to make the
collagen sheet soluble in hot water. such a sheet is used for packing
foot~stufF portions that are prepared in hot water. The unopened pack is
placed in hot water Where the sheet dissolves and the content of the pack is
thereby released. In US-PS 3 664 849, a moisture-resistant sheet of
enzyme-treated collagen is described for the manufacture of a meat snack
product.
The use of an edible flat collagen sheet to solve the above-described
prot~lems in the preparation of smoked fish products is, however, not to be
found in the prior art.
The subject of the invention is the use of edible flat artificial
col7.agen sheets to solve the above-described problems in the case of smoked
f ist~ products .
These collagen sheets are obtained from the corium of bovine hides.
The outer, so-called grain layer for the manufacture of leather is removed
from the bovine hide in a uniform thickness of from 2 to 4 mm depending on the
int~:nded use. The remaining inner part, the so-called, fleshing, is cleaned
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by acraping off meat, fat and loose connective tissue and consists ultimately
of ithe actual subcutaneous connective tissue, the corium. This is a close
network of collagen fibres that may be more than 1 cm thick. By chemical and
mechanical degradation the collagen fibres of the corium are converted into
the form of a pourable aqueous mass and plasticisers and cross-linking agents
are added. The collagen fibre mass is then cast in uniform thickness onto a
suitable conveyor belt that is guided through a drying tunnel, and is thus
dried. For use, the collagen sheets are produced in rolls 30 m long and
approximately 18 - 36 cm wide, even up to 57 cm (the thickness of the collagen
sheet ranges from 10 - 50 cm, preferably from 15 - 25 cm. The rolls are
soaked in water and cut to correspond to the size of the salmon and applied to
the cut section of the salmon halves.
In the preparation of foodstuffs that are further processed in
compact (dressed and/or smoked) form, the piece of fish is, after curing,
wrapped up in the edible flat collagen sheet and then introduced into a
tubular elastic net vWhich is closed at both ends with a clip or string.
Subsequently, in any desired sequence, the fish is mildly smoked and dressed,
usually hanging or lying on wire grids, in the smoking and cooking chamber.
Surprisingly, the collagen sheet does not stick to the net. The latter can
easily be removed after cooling by cutting it parallel to a longitudinal
thread. Owing to the inherent elastic tension the net then springs away from
the fish. Between the sheet and fish, on the other hand, there is an intimate
bond.
By comparison with the hitherto used gold-beater's skins, the use
according to the invention of edible collagen sheets has numerous advantages.
Firstly the demand for edible collagen sheets in the quantities conceivable
for the purposes already known and for the purposes according to the invention
can be met without any difficulty. By contrast, the supply of gold-beater's
skins is limited by the number of bovine slaughters in abattoirs with
integrated gut commercialization. After the chemical degradation, the
collagen mass is practically germ-free. Therefore, the collagen sheet has on
its surface no more microbes than other factory-fresh articles and therefore
requires no preliminary cleaning treatment. By contrast, owing to the
manufacturing conditions, gold-beater's skins are contaminated with bacteria
and resistant spores, as a result of which the storage quality of products
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made therefrom is reduced. The collagen sheet is neutral as regards smell and
taste. Used in accordance with the invention it is frequently not even
noticed by the consumer.
In addition, collagen sheets always have the same thickness and
strength, whereas gold beater's skins often have thin areas and must therefore
be processed very carefully. The collagen sheets are simpler to handle
because they are cut from a roll and consequently they are always of optimal
size in relation to the piece of fish to be processed. In the case of gold-
bea.ter's skins, there are always limitations imposed by the naturally
determined sizes of the individual pieces. Consequently, there is
substantially less waste in the case of collagen sheets. Also, the edible
artificial collagen sheets are cheaper than gold-beater's skins.
The edible flat artificial collagen sheets used in accordance with
the: invention may advantageously be coloured with dyes that are suitable for
foodstuffs, thus extending their field of application. For this purpose
pigments, such as titanium dioxide, iron oxides from yellow through red to
brown and black, are equally as suitable as natural substances, such as, for
example, annatto, curcuma or lactoflavin, and artificial dyestuffs such as
carazael, erythrosin or amaranth.
A further advantage as regards industrial processing is achieved in
accordance with a preferred embodiment of the invention when the edible
collagen sheets, instead of being used wet, that is to say soaked in water, as
wa:: customary also in the case of gold-beater's skins, are applied dry. For
th3.s mode of application the collagen sheet is coated with edible oil. The
additional advantage of this special mode of application resides in the fact
that the tear-resistance of the collagen sheet then dry is considerably higher
than its tear-resistance when wet, as the following table shows:
collagen sheet kg wet dry
tear-resistance longitud- p:26 0.8
finally
2 cm strips .~ transversely 0.26 i.5
_ p _
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The oils used for coating must not become rancid. There therefore
come into consideration only highly saturated fatty acids with the lowest
iodine numbers as components of triglycerides, but also mixtures of mono-, di-
and/or tri-glycerides. The oils advantageously incorporate anti-oxidants, for
example, ascorbates, tocopherols, gallates, butylated hydroxyanisole (BHA)
and/or butylated hydroxy toluene (BHT). In addition to the better
tear-resistance when dry, a further advantage of the oil-coated collagen sheet
is that when being handled, for example on packing tables, they slide better
than wet sheets. The oil coating is obviously not limited to colourless
sheets. In the case of especially deeply dyed sheets, for example sheets that
have been dyed black, here is also the further advantage that the goods packed
therein are given the desired sheen by the oil.
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