The present invention relates to a process for stabilising the colour
of cured, cooked comminuted meat products during storage.
Light-induced discolourisation of sliced and gas-packed charcuterie
products during display in illuminated cabinets in supermarkets, is a frequent
problem, due to high levels of oxygen in the packages and is caused by the presence
in the cured, cooked charcuterie products of a pink pigment which is not stable
to oxygen in the presence of light and which turns brown on storage. The oxygen
present in the pack may come from either the production process, the product itself
or from the exterior if the film of the package is not an efficient barrier. Acceptable
colour stability can be achieved by adding oxygen scavengers such as "Ageless"
manufactured by Mitsubishi Gas Chemical Company, Inc. to the package. "Ageless"
is an oxygen absorber based on iron powder which is produced in small pouches,
and effectively binds residual oxygen. In US-A-3780192, there is described a process
for accelerating the cure colour in meat by adding iron or an iron salt to the
curing medium in the presence of an enediol or diketone reducing agent. It is
also known to use encapsulated iron with lipid coatings for food fortification
Although added ferrous and ferric salts consume oxygen in cured,
cooked charcuterie products and protect against discolourisation during display,
the products become initially an undesirable yellow.
We have now found, surprisingly, that iron salts encapsulated with
a thermoresistant capsule which is permeable to oxygen are capable of stabilising
the colour of cured, cooked charcuterie products without the formation of an undesirable
Accordingly, the present invention provides a process of curing comminuted
meat which comprises adding an edible iron salt to the curing medium, characterised
in that the iron salt is encapsulated with an edible thermoresistant capsule which
is permeable to oxygen.
The iron salt is preferably, although not necessarily, a water-soluble
salt and may be a ferrous or ferric salt, for instance, a sulphate, chloride, phosphate
The amount of the iron salt (measured as elemental iron) added to
the curing medium may be from 10 to 100 ppm, preferably from 15 to 80 ppm and especially
from 20 to 50 ppm by weight based on the total weight.
The thermoresistant capsule is preferably made of a material which
is impermeable or substantially impermeable to the iron salt and is preferably
insoluble or substantially insoluble in cold water, e.g. water at ambient temperature
or below, e.g. from 20° to 35°C. By "thermoresistant" in this invention, we mean
that the capsule does not break down at the cooking temperature of the meat e.g.
from 70° to 80°C. Examples of suitable materials are edible polymers such as substantially
cold water insoluble polysaccharides or gums e.g. agar, pectin. The amount of
capsule material may be from 60 to 600 ppm and preferably from 120 to 300 ppm by
weight, based on the total weight.
The encapsulation of the iron salt may, for example, be performed
by conventional encapsulation techniques or by mixing or dispersing the iron salt
in a solution or dispersion of the capsule material and drying or setting into
a gel according to the nature of the capsule material. The encapsulated iron salt
may contain from 0.3 to 3%, preferably from 1 to 2.75% by weight of iron salt (measured
as iron), from 2 to 20%, preferably from 4 to 10% by weight of the capsule material
and from 85 to 95% by weight of water, each based on the total weight of the gel.
If desired, up to 10% by weight of dextrose may be added based on the weight of
The amount of the encapsulated iron salt added to the curing medium
may be from 0.1 to 1.0%, preferably from 0.2 to 0.6% and especially from 0.25 to
0.5% by weight based on the total weight.
Any conventional curing medium may be used e.g. one containing sodium
nitrate, potassium nitrate, sodium nitrite or potassium nitrite or any mixture
thereof together with a reducing agent such as sodium ascorbate or sodium isoascorbate
with the addition of sodium chloride, sugar and spices. The curing medium may be
used either in the dry form or dissolved in water to form a pickle.
Preferably the encapsulated iron salt is added shortly before the
end of the comminution of the meat, preferably together with the reducing agent.
The comminution and the curing may conveniently be carried out at a temperature
from 2° to 15°C and preferably from 4° to 12°C.
After curing, the comminuted meat is cooked and gas-packed. In the
case of a meat sausage, the comminuted meat is filled into casings e.g. under vacuum
and then may be dried and smoked before cooking after which it is sliced and gas
The following Examples further illustrate the present invention.
Parts and percentages are given by weight unless otherwise stated.
A curing medium was prepared consisting of the following ingredients:
* The curing salt consisted of 0.6 parts sodium nitrite and 1.35
parts sodium chloride.
Parts by weight
Meat / fat
Curing Salt *
Water (as ice)
This mixture was placed in a chopper and comminuted to give a sausage
mix over a period of 20 minutes.
An encapsulated ferric phosphate was prepared by dispersing 3.5 parts
of ferric phosphate and 0.1 part of dextrose into an aqueous solution containing
5 parts of agar and 91.4 parts of water at 60°C and then allowing to set by cooling.
The gel formed was cut in small cubes (3x3x3 mm) and added together with 10 parts
of sodium ascorbate in an amount of 0.31% to the sausage mix shortly before the
end of the chopping cycle at 10°C.
The comminuted meat was vacuum filled into collagen casings having
a diameter of 90 mm, dried for 20 minutes at 60°C and cooked at a temperature of
78°C in a cooking chamber until the core temperature was 72°C. Afterwards the
sausages were showered with cold water for 60 minutes for cooling and then stored
for one day in a chilling room at 2°C. The sausages were cut into slices 1.4 mm
thick, and batches containing 10 slices were gas packed in modified atmosphere
packages (2 mm headspace, 20% CO2, 80% N2).
In order to determine the colour stability of the sausages, colour
measurements were made on opened samples with a Minolta Chromameter:
- a) directly after packaging (I)
- b) after 12 days storage in the dark (II), and
- c) after 12 days storage - 4 days in the dark and 8 days under the light
(III) (2000 lux, 13 hours per day)
Comparisons were made with sausages containing no additives (Ref),
an equivalent amount of agar alone and iron alone and the results are shown in
Table 1 in which the redness of the samples is indicated by a* and the yellowness
by b*. It should be noted that:
- a difference of 1 in redness or yellowness between two samples is not visible,
- the ground colour is acceptable when a* appears greater than or equal to b*
Time after packaging
Ref. a* / b*
Agar alone a* / b*
Iron salt in agar a* / b*
Iron salt alone a* / b*
During these trials the residual oxygen after packaging was abnormally
high (1% in the reference after 12 days), which explains the magnitude of the discolouration,
and some discolouration in light for the samples with iron. When encapsulated
in agar gel, the iron salts provide colour stability in light and produce much
less non-light dependent discolouration when compared with iron salt alone. It
is apparent that when iron salts are added in encapsulated form, they provide an
acceptable colour, stable under light.
After 5 weeks storage, no effect on microbial growth, no or very
little effect on the sensory properties and no effect on the rancidity were observed.
A similar procedure to that described in Example 1 was followed except
that 2.5 parts of ferric phosphate were dispersed into the encapsulating medium.
The redness and yellowness (a*/b*) of samples of sausages after 1, 2 and 3 weeks
storage compared with a reference sample containing no additive are shown in Table
Time after packaging
Even after 33 days storage in light, the colour of the sausage with
encapsulated iron was still stable under the light. During storage, the redness
of the whole sausage was very stable and although the yellowness tended to increase
the colour was still acceptable.