Note: Descriptions are shown in the official language in which they were submitted.
2~.?~
IMPROVEMENTS IN AND RELATING TO PROTEIN PRODUCTS
The present invention relates to improvements in and relating to
protein products and in particular to the production of collagen
fibres and to the incoporation of collagen and collagen-containing
compositions into protein products.
According to the present invention there is provided a process of
producing collagen fibres which comprises, while maintaining the
temperature sufficiently low to prevent substantial conversion of
collagen to gelatin, comminuting tissues containing collagen,
drying the commLnuted product, and thereafter milling the dried
material.
Furthermore there is provided a process whereby the collagen fibre
thus produced is added to proteln products.
The tissues which may be used as starting material for the process
of the invention include, for example, animal tissues including
mammalian connective tissue, sinewsj dermis (split skin or corium
after removal of the outer skin layers from hide or head hide),
bird skins and connective tissue, reptile skins and connective
tissue, and fish skin~;and conne~ctive~tissue.~Other~sources of the
tlssues which may be used;in~accordance with the lnvention
comprise decalcificated bone dentlné,~and collagen-containing
tissues from the cardiovascular system, synovial membrane, viscera
:
subcotaneous membrane, fetal~dermis~, vitreous~humour,
intervertebral discs, basement membrane, lens capsule, kidney
glomeruli, placental membrane, and lung and muscle tissues.
Preferred tissues include mammalian connective tissues or sinews,
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~o~os~
-- 2 --
such as ligaments, cartilage and tendon, for example, 'Backstraps'
or 'Paddi wacks' from cattle. Other preferred sources of the
collagen used in the process of the invention are fish skins and
the dermis of animals whose skins are usually consumed as food
constituents, although bovine dermis is also a prefereed source
providing that its use is within the provisions of the prevailing
food regulations.
The collagen fibres produced according to the present invention
may also contain smaller quantities of other structural proteins,
such as elastin, reticulin, connectin and desmin, and also
mucopolysaccharides which are all naturally associated with
collagen in varylng amounts in tissues.
Preferably, residual 1esh and fats are manually or otherwise
removed, for example by scraping, tumble abrasion or by soaking in
salts such as sodium chloride or in enzyme preparations such as
papain. Soluble non-collagenous proteins and polysaccharides may
be removed, if desired, along with a fraction of the soluble
collagen, by soaking for example in a solution of sodium acetate,
sodium dihydrogen phosphate or potassium chloride. These
procedures may also serve to remove other soluble materials
present, such a glycans and~ saponified fats. ~Such soluble
materials may also be removed, if~desired~, by soakiDg in saturated
white lime solut~ion and thereafter removing excess calcium.
Reducing the pH value to or towards the isoelectric point (pH~.6)
for example to pH5.0, to provide enhanced storage stability in the
treated tissue material may be desirable following treatment with
salt solutions.
2CO~Q~;~
Animal tissues rich in collagen, such as those collected from
abattoirs may conveniently be used immediately or be stored by
freeezing9 for example at minus 20C., or by buffering, for
example in a solution of a weak acid, such as citric acid, or in
citric acid and sodium citrate, at for example pH5.0, or by
pickling, for example in a solution of sodium chloride and a
strong acid, such as hydrochloric acid or sulphuric acid. The
source of the tissues is conveniently bovine, but other
collagen-containing materials, for instance materials from pigs,
sheep, goats, game (including deer, eland and antelope), rabbit,
hare, kangaroo, dog, monkey, camel, buffalo, horse, birds such as
poultry (including chicken, duck, goose and turkey), pigeon and
game birds, reptiles (including turtles and snakes), fish
(including salmon, trout, eel, cod, herring, plaice, whiting,
halibut, turbot, ling, squid, tuna, sardines, swordfish, dogfish,
and shark), marlne mammals (includlng whales), amphibians
(lncluding frogs), or crustacea (including shellfish, crayfish,
lobster, crab, shrimps and prawns) may also be used as starting
materials in the process of the invention. If pork (for example
from pig achilles tendon) or chicken (or example from defeathered
skin or hen neck skin rich in collagen) or turkey ( for example
from leg sinews) or other collagen-containing tissues are used, it
is preferred that these have a low fat content. Where fat
contents are particularly high then fat rendering at low
temperatures (for example below 60C) mechanically screw pressing,
solvent extraction, with for example, hexane, and treatment with
lipase enzymes, such as fungal lipases~, may be advantageous.
It is preferred to carry out sample analyses of the cleaned
tissues in order to determine the protein (particularly the
collagen content), fat, moisture, calcium, ash, heavy metals, p~
value, and any microbiological contamination. This ls
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2~
particularly preferred when the fibrous collagen produced by the
process of the present invention is required to be of food grade
quality.
In accordance with the present invention, the tissue 0aterial is
comminuted, for example by being granulated, minced, cut, chopped,
or ground through a perforated plate, for example a 6mm perforated
plate. Conveniently, the material may be fed continuously into a
grinder to produce comminuted pieces, while ensuring that any
temperature rise during the comminuting process is kept to a
minimum. Comminuting tissues taken straight from a freezer, for
example tissues which have been maintained at a temperature of
minus 20C, are preferred. It has been found convenient, for
example, to arrange that the material is comminuted into pieces of
about five millimetres in diameter.
If desired, the comminuted product thu6 obtained may be
pasteurised or sterilised, or treated to retard microbial growth,
for instance by treatment for a short period with dry high
pressure steam, with hot fats or oils or with ultra-violet light
or ionising radiation. Precautions are preferably taken to ensure
that the minimum of moisture and heat transfe~r occure to the
~comminuted product during the pasteurisation or sterilisation. It
may be advantageous to carry out sample analysis of the
:
pasteurised or sterilised comminuted material after thorough
; sample mixing.
: : `::
The comminuted material may be dried by using any suitable
conventionaI drying or dehydrating means. Preferably the material
is peeaed to the drying stage with ~in~mum delay, and
20~5t'3
especially within a period not exceeding 24 hours. The drying may
be carried out by hot-air drying procedures such as in a tray
dryer or band drier, or drum drier, but other hot-air driers such
as tube driers, paddle or tumble driers or fluid bed driers may be
employed. Microwave driers, radio frequency driers, or infra-red
driers may also be used. Drying can also be carried out in vacuum
driers, extruders or in freeze driers, including for lnstance by
accelerated freeze drying and by freeze substitutlon. Drying may
also be carried out using direct solar heating or in smoking
o~Tens, when the pFoduct may also acquire a degree of microbial
preservation and smoke flavour. The comminuted material may also
be dehydrated by using fats or oils or in ethanol or other
solvents.
If conventional hot-alr drying of the comminuted material is
employed, then the drying is preferably effected at a temperature
up to and including 75C, particularly at a temperature within the
range from 35C to 75C. Within this range, drying at a
temperature of from 45C to 55C is especialIy pre~erred. If a
tray dryer or~a tube dryer is used, the drying process is
advantageously carrled out withLn~24 hours, a~nd preferably within
12 hours and~the material~may~advantageously by turned~
occasiQnally, and pr~eferably continuously, to facilitate even
- : :
; heating and to obviate~ localised~high~temperatures. Rapid drying
may be facilitated if relatlvely low loading densities of the
comminuted material are~employed, for example from 5 to lO
kilograms per square metre, with an air;speed of approximately 3
:
- metres per second, the dryer being maintained at an air
~ t mperature of approximately 55C and at a relative humidity of
20~ ?
approximately 40%.
If a fluid bed drier is employed, shorter drying times are
preferable, and the temperature is advantageously maintained below
75C and preferably below 60C. If microwave drying, radio
frequency drying, infra-red drying, solar heating, smoking, vacuum
drying, extrusion, or accelerated freeze drying methods are used,
the temperature is advantageously maintained below 75C and
preferably below 60C. If the drying is effected by dehydration
in fats or oils or other solvents, then a temperature of up to
approximately l20DC may be used, with the fat or oil or other
solvent acting as a molsture-expelling solvent while protecting
the collagen from being converted into gelatin as well as serving
to reduce protein denaturisation.
During the drying process, the moisture content of the material is
preferably reduced to less ~han 10% by weight.
The dried material is then milled in accordance with the present
lnventlon. A wide varlety of conventional milling means may be
employed. The use of a hammer mlll or a pin mlll is partlcularly
preferred, but pinned disc mills, cross beater mills~and turbo
mills may also be used. ~Advantageous1y the mllling may be
arranged to take place through a screen for example through a
2.5mm~ 3.0mm or 3.~5 = perforated screen to produce a collagen
fibre, or through a finer screen, for example, a perforated screen
of 2.0mm or less, to produce a~finely divided coIlagen fibre. The
prodoct may thus have indivldual e1bre lengths of up to lO
2~3~S~3
millimetres, preferably a fibre length within the range of from
0.1 to 5 millimetres, and especially of from 0.1 to 0.5 or from
0.5 to 5 millimetres, lnclusive depending on the application. Any
unground lumps passing through the screen are preferably separated
and recycled through the mill.
:
Any rise in temperature during the milling process is preferably
maintained at a minimum by careful control of the feed rate and by
air~cooling. However, it is particularly preferred that a coolant
is added to the material undergoing the milling if;there is any
possiblility of a substantial rise in temperature occuring. The
coolant may be, for example, liquid nitrogen or solid carbon
dioxide.
At all stages in the process of producing collagen fibres in
accordance with the invention, the temperature is maintained
sufficiently low to present substantial conversion of collagen to
gelatin. Preferably the temperature is kept below a maximum
temperature of 75C.
Cyclones can be used to collect the product;from the milling
process, and the product may then be passed through a metal
~detector and weighed~Into polyethylene containers.~
It is advantageous to carry out~aample analyses of the milled
pFoduct, after thorough sample mixing.~ A typlcal analysis of
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bovine collagen fibre produced in accordance with the present
invention is as follows:-
Protein 92%
Fat 2.8%
Moisture 5%
Ash 0.2%
Arsenic Less than one part per million
Lead Less than one part per million
A further example of a typical analysis of collagen fibresproduced in accordance with the present invention is as follows:-
Protein 85.7%
Fat 2.3%
Moisture 5.0%
Ash 7.0%
Arsenic Less than one paFt per million
Lead Less than one part per million
Percsnta~es and psrts st~ted ars~by welght. Ths protein ray becollagen alone or;it may contain other~structural;pro~tslns
naturally associated with collagen in varying~amounts in animal
tissues, such as~elastin, reticulin, connectin, and desmin. A
small amount of carbohydrate, in the`form of polysaccharides
naturally associated with collag5n in animal~tissues, msy also
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:
2~03053
be present. The bacterial specification of the collagen fibre is
preferably that of a substantially sterile material.
The collagen content of the material produced, or the content of
collagen plus the other structural proteins generally present in
the material produced, is preferably at least 85% by weight on a
dry weight basis, but it may be lower than thls if other
substances are present, for instance moisture, fat (including
animal fats, vegetable oils and hydrogenated animal and vegetable
olls), other proteins (including meat proteins, milk proteins, egg
proteins, vegetable proteins such a soya proCeins, microbial
proteins such as single cell proteins, and hydrolysed or autolysed
vegetable or meat proteins), or other foods, food ingredients or
food additives includlng cereals, carbohydrates such as sugars,
starches, modified starches, cellulose, modified cellulose and
pectins, polyhydric alcohols such as glycerol, polyethylene glycol
and sorbitol, gums such a xanthan gum, alginates and tragacanth
gum, salts such as sodium chloride, sodium pyrophosphate and
curing salts, spices, seasonings, flavoutlngs and colourings.
These additional substances may act as dllutents, humectants,
thickeners, or other functional ingredients~in the meat or meat
products, offals, fish or fish products or other protein products
::
or in cosmetic or medical products, comprising the collagen fibres
produced in accordance uith the~present invention.
The collagen fibre produced may then be added, in accordance with
the present invention, to protein products. The protein product
or products can comprise raw or cooked meat or meat products,
20~ 05~3
- 10 -
offals, fish and fish products, and other protein products for
food for human use, pet food, animal feed or fish food use, and
also for use in cosmetic products and medical products. The
addition may be made by any of a wide range of conventional
mixing, adding, blending or compounding means.
CollagPn fibres produced by any other methDd may also be added in
accordance with the present invention. Such methods comprise, for
nstance, part extraction of collagen from animal tissues with
(for example) sodium citrate buffer solution of pH 3.7 to 4.3 and
reconstitution into needle-like crystalline fibres by dialysis
against water or diluted salt solutions such as disodium hydrogen
phosphate solution; bowl chopping, slurrying and extruding
collagen containing tissues into fibres, followed by chopping and
drying as required; and cell culture of collagen into formed
fibres. These collagen fibres may be added by the process of the
present invention to protein products such as protein products for
use as food for human consumption, pet foods, animal feeds, fish
food, cosmetic products and medical products.
The collagen fibre is particularly us;efuI~for restructuring poorIy
textured meats (particularly comminuted meats1, meat productsg
offals, fish, particularly comminuted fish, ~fish products, and
other protein products so~as~to enhance their textural properties,
water retention, fat retention, eating quality,~]uiciness, shape `
:: :
and size retention, or consumer appeal or to increase their meat
content, fish content or protein content, or to~make more cost
effective products. The enhanced appeal need not be only to the
: :
human consumer, but may also have greater appeal to domestic pets
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2~o~
when used in pet foods and to farm animals and fish when used in
animal feeds and in fish foods.
Preferably collagen fibre from a partlcular animal species,
including individual species of mammals, birds, reptiles or fish,
is added to the product derived from the ssme species, but
collagen fibres from any particular species can be added to the
product derived from a different species, whether mammalian, bird,
!
reptile or fish, and also to protein products derlved from
vegetable or microbial sources.
:
The Eollowing example illustrates the incorporation of collagen
fibres in fish sticks in accordance with the present invention.
96 parts by weight of a frozen fish slurry of white fish, salmon
or crsb is defrosted into a paddle type mixer, and 4 parts by
weight of bovine collagen fibres are streamed in while mixing.
The temperature of the batch is raised to 4C while mixing is
continued, and the batch is~then immediatelg placed in moulds and
frozen. The fish sticks thus produced contain fish and added
: :
protein (beef collagen) for ingredient labelling purposes. If
fish collsgen fibres are used instead~of;the~bovine collagen
fibres, then thls would~be incloded~wlth the~total fish protein
content and labelled~accordingly.~The fish stlcks may be battered
and crumb coated a;s required,~or~precosted using finely divided
collagen fibres and seasoned or coated~with, for example, crumb,
almonds, potato, dried fruit and~sweet flavoured coatings.
Mechanically recovered meat (MRM) is~generally low in collagen
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- 12 -
because gristles and matrix mucopolysaccharides are not
incorporated. Consequently, the addition of collagen fibres to
the MRM in accordance with the present invention can bring the
analysis of the product into line with that of traditional meat
cuts.
Incorporation of the collagen fibres is particularly advantageous
for example, in the formulation of burgers, where gristle-free
meat of approximately 80% meat content can be converted into
American-style burgers with excellent juiciness and retention of
shape by the addition of 4% bovine coIlagen fibres.
The following example illustrates the incorporation of collagen
fibres into beef burgers in accordance with the present invention.
Raw degristled forequarter beef (40% by weight) is minced and
transferred to a paddle type mixer, and bovine MRM (45~ by weight)
and sodium chloride (1% by weight) are added and thoroughly mixed
in. Bovine collagen fibres (4% by weight) are then streamed in
while further mixing, and water (10% by weight) is added and mixed
in thoroughly. The temperature is raised to 4C and the mix is
formed into any desired shape and size in pattie forming~machines,
and then immediately frozen. The lngredien~t list of the resulting
"
beef burgers will be: beef, water and salt, and the analysis will
be 100% meat. ~
The MRM or other poorly~textured meats (especially comminuted
meats), meat products, ofials, fish (especially comminuted fish),
fish products and other protein products can be raw, sterilised
20~)3~)~;3
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pasteurised, partly cooked or cooked before the collagen fibre is
added to it in accordance with the process of the invention.
However, it is preferred that the product comprising the admixed
collagen flbre, subsequently to the admixture, is subjected to a
cooking or heating procedure. In this way the functional
properties of the collagen fibres can be fully, or substantially
fully, exhlbited in the product of~the invention.
The use of collagen fibres in accordance with the invention is
also advantageous in the production of continental-type sausages
either cooked (for Lnstance frankfurters) or cured (for instance
bierwurst). Addition of the collagen fibre may thus snhance the
textural properties of the sausage products and act as a binder
where non-meat binders, such as soya derivatlves, cannot be used
because of legislation. In meat products incorporating offals,
for instance hearts, the percentage incorporation of the offals
may be increased and their textural properties improved by the
addition of collagen fibres. Reformed meats, if formed from
low-grade connective tissue products,~ such as raw or cooked MRM
aod offal, may be prepared ulth better;cohesiveness and at~lower
cost by the incorporation of collagen fibres~produced~by the
present Inventlon.~Fat retentlon~ln~partlcular~ls enhanced glvlng~
improved succulence~and the addltion~of~extra~lipids,~for instance
meat fats~, may~also be;aesisted;by~the~pre~sence of the incorporatd
collagen fibres, resulting in a~further improvement in~juiciness.
In blndlng properties, for exsmple~in~reformed meat~and reformed
fish for foods for human consumption~or for pet foods
: : ~: ~ ; ::: :
2~!~3~353
- 14 -
(particularly when MRM is used or when other comminuted meats or
fish are used which have lost cohesiveness), incorporation of the
collagen fibres can replace the addition of non-meat or non-fish
materials such a wheat gluten and soya protein, which are not
universally permitted in Continental style cooked meats, or of
bovine plasma which can not always be included within the
officially recorded meat content of the product. At the same
time, textural properties, water retention, fat retention, eating
qualities, juiciness, shape and size retention, meat or fish
content and/or consumer appeal may be substantially enhanced.
Products formed by restructuring offal proteins or bone proteins,
for example by high-temperature extrusion or by deposition (for
instance into alkali), may be further lmproved by incorporating
collagen fibres in accordance with the present invention.
Collagen fibres can be advantageously included in meat or meat
products to adjust the protein to total meat ratio to meet
prevailing legislation.
Ueat products, fish products or other protein producs which have
been passed through a cooker extruder,~with or without
co-extrusion of pastry or potato or starches~(for instance rice
starch) to produce logs or coated~logs of cooked products in any
of a variety of shapes, may be substantially improved in as
regards their textural propertles, water retention, fat retention,
eating quality, ~uiciness, shape and~slze retention, meat or fish
content, and/or consumer appeal by the addition of collagen fibres
20~30S3
- 15 -
in accordance with the present invention. Similar formed
products, produced in extruders through vacuum fillers via shaped
nozzles capable of substantially fur~her compressing the product,
may also be improved by the sddition of the collagen fibres in
accordance with the present invention.
The incorporation sf the collagen fibres into the protein product
can advantageously be combined wth the addition of salts such as
sodium chloride, sodium pyrophoephate and curing salts to enhance
still further the binding properties, moisture retentlon or other
desirable characteristics.
The incorporation of collagen flbres into meat or meat products
can also be effected with advantage simultaneously with the
addition of gums, preferably xanthum gum, to improve still further
the textural properties and moisture retention during cooking.
Such gums can be added by any of a variety of conventional means,
for instance by injection, tumbling, massaging or admixlng. For
example, if xanthan gum ls used, the~gum solutlon preferaby
contains from 0.2% to 1.0% by weight~of the gum.
In all the foregoing appllcatlons to~whlch the collagen flbres of
the invention can~be put,~the~ collagen fibres appear to act in two
major ways. FirstIy, when mixed with~other proteins such as
mamma~lian muscle proteins in~an aqaeous environment they swell
somewhat due to hydration~and, bsing fibrous and of optimum
length, they physically bind the fibres of the muscle proteins
together. On cooking or othsr subsequsnt heating or re-cooking,
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~0~3053
- 16 -
the shortening of the collagen fibres which occurs at a
temperature in the range from about 55C to 65C as well as the
physical presence of the coll~gen fibres themselves causes the
eating quality of the product to be greatly improved by
introducing a degree of chewiness or texture into the product,
thus simulating the eating qualities of a piece of steak.
Secondly, they swell at higher temperatures and become softened as
they take up water and partially convert to soluble gelatin on
cooking at about 70C to 85C thus causing an improvement in
tenderness. At the same time, and to a greater extent on
subsequent cooling, an increase in water retention and improved
perceived ~uiciness is caused by the gelling properties of the
gelatin, giving an overall improvement in size and shape retention
and enhanced eating quality. At cooking temperatures above 85C
(internal temperature) then increasing proportions of the collagen
fibres are converted into soluble gelatin, thus causing a further
imp~ovement in tenderness but a reduction in the textural strength
of the product.
The application of pressure while forming the products containing
collagen fibres is advantageous, for instance the use of plate
freezers (for example at 5 p~s.i. at -40C~, extruders ~for
~example at up to 25 p.s.i.j and particularly vacuum flllers under
extrusion (for example at 25 to 5G p.s.i.j ideally through shaped
nozzles, especisIly the Z-bend configuration of extrusion nozzles.
: :
This may be due to a degree of alignment of the fibres and of
~their layering ln the most advantageous cases~by the application
of pressure in two directions and also to a more intimate binding
of the collagen fibres and the meat or flsh proteins for example
under the~application of the applied forces.
20~30~;3
- 17 ~
Collagen fibres in a finely divided state, typically with a fibre
length within the range of from 0.1 to 0.5 millimetres inclusive,
can be advantageously used as, or as part of, a predusting system
for protein products, particularly meat products and fish
products. For example, a finely divided collagen fibre (or
powder~ may be dusted onto a burger and heated to allow partial
conversion to gelatin, for instance by passing it through a heated
tunnel. Powder or granular coatings, such as spices, seasonings,
flavouring, colourings, nuts, potato, dried fruit, sweet flavoured
.
coatings and breadcrumbs, can be effectively bound to the
partially gelatineised collagen coating either by mixing them with
the collagen prior to the predusting stage or by adding them after
partial collagen gelatinisation. Thus the need to use a batter
mix prior to addition of the coating is eliminated and with it the
necessity to seal on the coating to prevent the migration of
moisture utilising, for example deep fat frying. Finely divided
collagen fibres can also be advantageously utilised as a
precoating system for protein products particularly meat and fish
products and ssaled by heatlng to allow batter coating and
enrobing with coatings such as crumb, potato and nuts without the
need for to further seal the product~by for example deep fat
frying. ~ ; ~
The present invention comprises collagen fibres when produced by
:
the process of the invention.
The present invention also comprises~protein products containing
incorporated collagen fibres when produced by ths process of the
:
zo~ ;3
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invention. The protein of the products may be raw, pasteurised or
sterilised, part cooked or cooked meat or meat products from
mammalian, bird, or reptile sources, offals, fish or fish
products, including products derived from whales, krill or
crustacea, or other proteins such as proteins of vegetable or
microbial origin, and products made from these proteins.
The following example further illustrates the present invention.
Raw mechanically recovered meat (MRM) is~brought up ln temperature
from deep frozen to 1C and from 1% to 6% and preferably
approximately 4~, by weight~of collagen fibre produced for
instance by the process described in this invention is added
portionwise and mixed thoroughly in a efficient blender, for
example in a double arm type ribbon trough mixer. The temperature
is brought up to 4C, the preferred maximum being 5C, and the
mixture is placed on freezer trays and plate frozen. On cooking
or precooking at an internal temperature of 65C to 100C (or from
115 to 125C for a shorter time in a pressure cooker or retort),
the collagen fibres contrace and then partially convert to
geletin, thus binding the product together and improving the
eating quallties. At temperatures substantially above~80C the
binding properties of the formed gelatin may be accentuated, but
the textural enhancement of the collagen fibres may be~reduced.
Conversion of the collagen fibres to gelatin~is approximately 5%
to 10% at 64C to 70C~ and 7%~to 15% at 75~C to 85C when held
: ,
for a short period. At 85C for~a prolonged period, conversion
may reach 50%. At 100C conversion may be 10% to 20% when held
for a short period, and up to~100% when held for about 4 hours.
: ~
Microwave heating tends preferentially to increase the solubility
of the collagen fibres relative to the muscle proteins in meat,
::
and hence lower internal temperatures can produce levels of
" . , , ..... ., .. ~ .-~ .
%~ 053
-- 19 --
gelatin equivalent to that obtained by higher internal
temperatures produced by conventional cooking means.
The products thus produced may be used for example as replacement
meat cuts by slicing, as steaks by forming, and as Chinese
stir-fry ingredients or meat lumps for canned meats, pet foods, or
soups, by dicing. A simllar set of products may be produced if
the raw material used in the process ls mechanically recovered
fish, for instance from deboning processes.
.
In MRM and other meats and meat products and mechanically
recovered fish and fish products, where the structure of the
tissue has been destroyed and which on cooking is no longer able
to prevent the egress of fluid released by proteins, collagen
fibres ca~ greatly increase water and lipid-holding capacities
thus reducing 'shrink' where it is derived from both aqueous and
fatty sources, for example in cooked meats. In such products, a
further improvement in water-holding capacity may be obtained by
the addition of gums, for instancè xanthan gum and alginates, and
of salts, for instance sodium chloride, sodlum pyrophosphate and
curing salts. In this manner, loss of juiclness and palatability
:
is obviated.
The incorporation of collagen fibre into freshly prepared MRM as
it emerges from the deboning machines, or after brief mixing to
standardise batches, can be highly advantageous as the MRM is at
the optimum temperature and its meat proteins are in the most
available etate to bind with the collagen f~bres.
. ~ . -- -- . .. .
.
.
2~3(:~3
- 20 -
Irradiation of the collagen fibres, or of the collagen raw
material, or of the protein product containing the collagen
fibres, particularly of the collagen fibres produced by the
process described in this invention, with sterilising doses of
ionising radiation (such as 5M rad) may cause an increase of
tenderness of the product due to a decrease in the shrink
temperature of the collagen fibres.
Collagen fibres or finely divided collagen fibres can be
advantageously used as carriers for flavourings, colourings and
other food additives, particularly for use in meat products, fish
products, and other protein products, that are cooked prior to
consumption.
Collagen fibres can be advantageously used as a source of protein
and of amino acids for nutritlonal purposes in food, pet food, and
animal feed, and also in fish food, where the flotation properties
of the collagen fibre in water can be combined with the flavour
and colour carrying properties of~the collaaen fibre in the
preparation of complete fish food formulations.
,
