Agriculture Reference
In-Depth Information
Table 4.1
Curing salts and additives
Ingredient
Level in curing brine
Function
Sodium chloride
15-30%
Preservative, improves texture
Sodium nitrate
a
0.15-1.5%
A source of nitrite
Sodium nitrite
a
500-1000 ppm
Preservative, reduced by meat enzymes to NO, which combined with
myoglobin (the uncured meat pigment) forms nitrosomyoglobin,
the cured meat pigment
Polyphosphates
2-4%
Reduce cooking losses, for example, during smoking, improve texture
Sugars, for example,
sucrose, maple syrup
1-4%
Improves flavour by masking the harshness of the salt
Liquid smoke
ca. 1%
Flavouring agent
Sodium ascorbate
b
0.2-1.0%
Reducing agent. Improves colour formation and stability by effecting
rapid reduction of NO
2
and NO
3
in the meat
a
In the United Kingdom, levels must not exceed 500 ppm NaNO
3
and 200 ppm NaNO
2
in the final product.
b
Varies considerably; refer to manufacturer's instructions.
fluid and then passes slowly inwards until it is evenly
distributed throughout the meat substance. A consider-
able amount of the moisture is removed when the salt
draws to the surface some of the fluid in which it
dissolves. Microscopically, salted meat, compared with
fresh meat, shows a diminution in the size of the
intercellular spaces as a result of loss of water.
Curing
may be defined as the addition of
salt
(NaCl)
and
nitrate/nitrite
or
nitric oxide
to the meat, which results
in a conversion of the meat pigments, predominantly
myoglobin, to the nitroso or cured form. Myoglobin in
freshly cut uncured meat is in the reduced form (purple),
which in contact with air is rapidly oxygenated to oxymy-
oglobin, which is bright red and responsible for familiar
colour of freshly cut meat. If oxidised, these pigments are
converted to metamyoglobin, which is unattractive and
gives a brown or grey colour. Under suitable conditions,
these pigments can be converted to the nitroso form
(nitrosomyoglobin) by the addition of nitric oxide. During
the curing process, nitric oxide is formed by reduction of
nitrites formed by bacteria from nitrates. Nitrosomyoglobin
gives freshly cut cured meat its bright red colour but is
unstable and rapidly oxidises to the brown and grey forms.
However, on heating, the nitrosomyoglobin is converted
to nitrosohaemochrome, a pink colour (e.g. of cooked
ham or corned beef ) as distinct from the grey and brown
of the cooked uncured meat (e.g. roast beef ).
can be used (Table 4.1). Each ingredient has a specific
function and is used accordingly.
Production of bacon and ham
Pork may be cured by either salting or pickling. Dry
salting gives a less consistent product and takes longer
and is therefore more expensive.
The raw material in the United Kingdom and Ireland,
an 80-100 kg live weight pig, is slaughtered and eviscer-
ated to produce an 80 kg carcase. Slaughter weights have
increased by 10 kg over the last decade to come closer to
the EU average of around a 90 kg carcase, Italy killing the
oldest and heaviest pigs producing a 125 kg carcase for
Parma ham production.
White-skinned pigs have traditionally been preferred
as the bacon rind has a more attractive appearance. A pig
with light shoulders; long, level back; and deep and level
flanks with broad hams is most likely to yield a carcase
well endowed in the region of the most valuable bacon
cuts, for in a side of bacon the collar and foreleg together
should not weigh more than 25% of the whole side.
After
stunning
and
bleeding
for at least 6 minutes, most
pig carcases in the British Isles are
scalded, dehaired,
singed
and
scraped
in preparation for bacon production
rather than being skinned. The scalding water may con-
tain different types of bacteria originating from the pig's
skin and gastrointestinal tract, including
Salmonella
. The
temperature of the water in the drag-through scalding
tank at 60°C is generally sufficient to reduce vegetative
growth. The skins of scalded pigs have low numbers of
both enteric pathogens and spoilage bacteria, but the sub-
sequent dehairing process recontaminates the skin. The
bacterial content of the muscle and viscera does, however,
Ingredients used in curing
Basically to produce a cured meat, only
sodium chloride
and a source of
nitric oxide
(
nitrate
or
nitrite
) are
required. However, with a demand by consumers for a
greater variety of cured meats in relation to saltiness and
other flavour components, a wide range of substances
