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CURED MEAT CUTS

Entire pieces of muscle meat and reconstituted products

Curing is the treatment of muscle meat with common salt (NaCl) and sodium nitrite1 (NaNO2). It is applied in the manufacture of sausages or similar products, but also for larger pieces of meat selected for cured meat specialities. In the past, when refrigeration was not commonly available, curing was mainly applied to extend the storage life of entire pieces of muscle meat by using the preserving effects of common salt (in high concentrations) and to a lesser extent sodium nitrite. In modern meat processing, this aspect is less important as more efficient meat preservation methods, in particular cooling and freezing, are available. Curing is now mainly applied to achieve a pink-red colour as well as a typical flavour and taste in processed meat products (see page 36, 68).


Fig. 213: Cured-raw pork loin ("coppa"), left, and cured-cooked pork loin ("smoked loin"), right

Cured meat cuts made of entire pieces of muscle meat, constitute a specific group of meat products. The opposite are comminuted cured meat products, to which sausages and similar preparations belong (see relevant chapters page 115, 127, 149). In principle, the cured meat cuts can be sub-divided into two groups, cured-raw meats and cured-cooked meats (Fig. 213).

For cured-raw meats, usually entire muscle groups in their anatomical connection are used. Typical examples are whole pork hind legs or parts of hind legs (topside, silverside, round), pork loins and bellies, beef briskets and/or cuts from beef hindquarter. In some regions mutton legs, ostrich breasts and game meat cuts are also produced as cured meat cuts.


1) Sodium or potassium nitrate (NaNO3/KNO3) are alternative curing substances but generally not needed and not recommended for the usual processing methods, if sodium nitrite is available (see page 35, 119).

For cured-cooked meats, similar meat cuts as mentioned above and smaller meat pieces can be used as raw material. These pieces vary in size and can be much smaller than individual muscles. After curing (in most cases combined with tumbling, see page 28), the pieces are joined together in special containers (moulds) and/or casings prior to cooking to “reconstituted meat” (see page 178).

The curing for both groups, cured-raw and cured-cooked, is in principle similar: Small amounts of nitrite, either as dry salt or as salt solution in water, have to be brought in close contact with the muscle tissue in order to effect the curing reaction with the muscle pigment myoglobin (for details on curing techniques see page 37).

The decisive difference between the two groups of cured meats is:

Cured-raw meat

For cured-raw meat, fresh meat of good hygienic quality should be used, as this aspect has a crucial impact on the long shelf-life and typical flavour of the final products. The fresh meat selected for cured-raw products should have a low pH, as lower pH-values result in lower water binding capacity, thus allowing for adequate release of water (drying) during the fermentation and ripening phase. If the meat remains in the high pH range and retains high moisture content, it would spoil during the prolonged ripening phase. pH-values below 5.6 in the selected fresh lean pork and even lower for beef are recommended. Meat from older animals is equally suitable due to its decreased water holding capacity.


Raw-cured meat cuts are not submitted to any heat treatment and consumed raw. The exception is Jinhua ham (page 174), which Chinese consumers prefer to boil in soups or similar, but it can equally be eaten raw.

Curing and ripening

Products under this category are manufactured by applying curing salt (combination of 99.5% common salt and 0.5% sodium nitrite) either dry or in solution or in a combination of both (see page 173, 174). After the curing, specific processes of fermentation, drying and ripening take place in the meat. The duration depends on the size of the meat pieces and the type of products, but lasts usually between three to six months. For some raw ham specialties the process can take up to 24 months.

a) Dry curing


Fig. 214: Rubbing with salt for dry curing


Fig. 215: Dry-salting. Periodic re-arrangement of meat piles

Dry-salting is the traditional favoured method for raw-cured meat. Meat cuts (entire pieces of muscle meat) are rubbed with curing salt (see Fig. 63, 64, 214). Thereafter these meat pieces are packed in curing tanks and piled on top of each other with layers of curing salt between them and stored at low temperatures (0 to +4°C). The curing salt infiltrates the meat tissue and at the same time liquid from the meat tissue is extracted by the salt surrounding the meat. The liquid accumulates at the bottom of the curing container. Sometimes, this liquid covers the lower piles of meat pieces and contributes an additional curing and flavouring effect, in other cases this liquid is drained out. Due to the weight of the rubbed meat cuts, the pressure within the pile is higher at the bottom of the container. This results in faster liquid loss and salt infiltration. For equal distribution (uniform exchange process) re-piling and adding of dry curing salt should be carried out every seven days with the lower piles up and the upper ones down (see Fig. 215).

Depending on the size of the meat cuts, the curing process alone can last up to several weeks for equal penetration of the meat cuts with curing salt. At temperatures of about +4°C, a pork shoulder takes about two weeks, a leg of pork about four weeks. The same curing periods apply to beef cuts of comparable size. In all dry-curing methods the meat should be covered to protect it from the air. The liquid, which may develop in the first few days, when the salt extracts the juice from the meat, can be removed, but additional smaller amounts of dry curing mix must than be sprinkled over the meat cuts. If the liquid is left at the bottom of the container, care should be taken that re-piling is done more frequently (see Fig. 215).

In combination with the dry curing salt, also spices and sugars for flavouring and sodium ascorbate for enhancement of a typical curing colour (pickling-red) are used simultaneously. The use of ascorbic acid (instead of sodium ascorbate) in curing mixes and/or brines is discouraged as it could lead to a violent chemical reaction with the nitrite, especially when dissolved in water together with nitrite. The result would be fast nitrite breakdown and loss of its functional property.

As exception to the common technology of using curing salt (containing nitrite or nitrate, or a mixture of both, see also page 119), some well-known traditional cured-raw ham products (e.g. “Parma Ham” and “San Daniele Ham” in Italy, “Jinhua Ham” in China “Jamon Serrano” in Spain, “Jambon Savoie” in France, or “Virginia Ham” in US) are fabricated without nitrite using common salt only. For these products carefully selected pork hind legs with bone are used. Although no nitrite is used, a stable red colour is achieved in these cured-raw ham products. This red colour derives from the natural meat colour intensified by the drying and ripening process, in some instances traces of nitrite and nitrate in salt and spices may also contribute.

b) Dry-Wet curing

This method is also sometimes practiced in order to facilitate a standardized curing process in bigger meat cuts of slightly different size in one curing container. The meat cuts are dry-salted as usual and piled up layer by layer in the curing containers. The liquid extracted from the meat tissue by salt accumulates at the bottom of the curing container and is topped up to reach to upper piles by separately prepared brine, usually with 15-20% curing salt concentration. The brine must be checked periodically for density and salt concentration and replenished as necessary to assure even curing. The curing brine can also contain spices for enhanced flavour and sodium ascorbate to further stabilize the curing colour. After 5-7 days the meat cuts are re-piled and covered again by the curing brine. As a rule of the thumb, the curing time for the biggest meat cut is 2 days per kg of its weight at a brine/meat ratio of 1:2. This is followed by a drying/ripening phase.

Fast curing with additional brine injection

For some raw-cured products smaller amounts of curing brine are injected directly into the muscle tissue to accelerate the curing process. This technique significantly shortens curing periods, as curing substances migrate in both directions, from outside to inside and from central to less central parts. But because of the accelerated process, the curing flavour remains less intensive and texture of these products remains softer then in products applying dry or dry-wet curing. The shelf life is also reduced significantly and most products are kept refrigerated. Typical products of this fast-cured type are cured/smoked pork loin and breakfast ham (low price raw ham). Fast curing with injection of curing brine will therefore remain the method of choice for rapid turnover cured-cooked meat products only.


Fig. 216: Quick cured-raw breakfast ham
Vacuum packed to stop weight loss

c) Ripening and fermentation of cured-raw meat products

After the curing period, a ripening (maturing) and fermentation period is required for the full development of the typical flavour of raw-cured meat products. At the start of the ripening period, all curing salt is removed from the meat surfaces and the meat cuts are either spread on trays or hung on sticks in refrigerated rooms at initial temperatures between +2 and +5°C (Fig. 217). During this phase the cured meat cuts develop the typical flavour, colour and texture. In the course of the ripening period, temperatures are gradually increased, but should not exceed +12°C. Ripening is a very slow process and can take up to several months for specific products. Throughout the entire process (curing, ripening, fermentation) the meat looses a significant portion of its water content. This process starts during curing, when salt penetrates the meat in exchange for moisture, and is continued during ripening, when moisture from the meat evaporates and dry partially. At the end of the ripening phase the salt concentration should reach ³4.5% (aW 0.96) as this ensures a microbiologically stable product. Hams dried and fermented in natural or climatized air are called “air dried hams” (Fig. 218, 219). Air dried beef is a very tasty product and attracts high prices (Fig. 221)


Fig. 217: Drying and ripening stage of cured-raw hams (suspended in ripening room after completion of curing)

For “Parma Ham”, “San Daniele Ham” and “Jamon Serrano”, the whole process including curing, drying, fermentation and ripening leading to the product ready for consumption can take up to 24 months. Process periods (curing, drying, fermentation and ripening) for other raw-cured products see table 9.

d) Smoking

For many of the larger raw-cured meat cuts and depending on the region it is common to apply short sequences of cold smoke (around 20°C) (see page 41) during the ripening stage, especially in regions with wet and/or cold climate. The high air humidity in these regions increases the risk of mould growth on the meat surfaces, which can be prevented by the antimicrobial effect of smoke. This category of products is called “smoked raw hams” (Fig. 220).


Table 9: Treatment for raw fermented products

 

Curing period

temp

Post-curing period

Optional

cold smoke

Ripening,

fermentation, drying

Pork leg (Ham)
dry cured

15-30 days

4-8°C

3-5 days

8-12°C

5-30 days

12-18°C

Normally up to 9 months (Parma etc. up to 24 months)

(water content in muscle tissue ~62%); +2 to +5°C, later higher

Smaller meat pieces

dry cured

4-10 days

4-10°C

1-3 days

8-12°C

 

Few days to few weeks (water content in muscle tissue 67% and above); +4 to +10°C, later higher



Fig. 218: Well ripened ham, bone-in, air dried


Fig. 220: Raw ham, heavily smoked


Fig. 219: Well ripened ham, bone-in, air-dried


Fig. 221: Beef, dry cured, rectangular shaped through pressure during curing and fermentation, ripening period several months, surface layer edible yeasts

Cured-cooked meat products (recipes page 422 – 423)

Raw meat material used for cured-cooked meat products is mainly pork derived from hind leg, shoulder or loin. In some regions, lean muscle meat from other species (here mainly from beef carcasses, Fig. 231) may also be processed to local cured-cooked specialties. In some regions cured-cooked beef tongue is a delicacy. Meat from younger animals with higher pH values is preferred (for pork pH above 5.6, preferably 5.8-6.0). Higher pH values are associated with better water binding capacity. Contrary to cured-raw products, where low pH-values are desirable to boost moisture decrease, high pH-values are desirable for cured-cooked products to retain the full moisture content.

For high quality products and regional delicacies, entire pieces of muscle meat (Fig. 226, 230) are cured and cooked. These meat pieces may consist of defined muscle groups, such as ham or large back muscle. Medium quality cured-cooked meat products are normally reconstituted (Fig. 228, 231) from smaller size lean muscle parts, which are cured and tumbled (see page 184), tightly filled in special containers and cooked (Fig. 413, 414). For the low-cost market so-called “re-formed” products have become popular. For these products, small muscle pieces and lean trimmings are mixed with brine (water, salt, binders, extenders, etc., see page 180). The mixture is tumbled, stuffed into casings or cans and heat treated. The individual processes are described below. The meat temperature should ideally be kept below +4°C during the curing process.


Fig. 222: pH – measurement in ham

Processing Technology

There are slight differences in the processing technology of cured-cooked products, mainly depending on the size of the meat parts used for product manufacture. Curing brine is administered in all products. This is usually done by brine injection.

Even distribution of the injected brine is achieved by treating the injected meat pieces in a meat tumbler (Fig. 28, 228). When no tumbler is available, “resting periods” (see page 182, 185) for the meat pieces are needed.

When meat pieces are too small for brine injection, they are transferred untreated into the tumbler together with an adequate amount of curing brine, which will be absorbed into the meat tissue through the massaging effect of the tumbling.


Preparation and application of curing brines

An essential part of cured-cooked meat processing is the use of curing brine. For some products, curing brine is partly injected directly into the meat tissue and partly used in solution in which the injected meat cuts are submerged prior to cooking. In re-constituted cured-cooked meat products, a mixture of meat pieces, trimmings and curing brine (often enriched with additives for increased binding) is subjected to tumbling. All these curing brines have different compositions and salt concentrations.

Table 10: Injection of curing brine

Cooked cured

Concentration % (curing salt)

Volume % (injected brine)

8-14

15-20

All curing brines contain nitrite curing salt dissolved in potable water. The recommended salt concentration in brines for cured-cooked meat pieces is 8-14%. Seasonings are also often added to a brine to impart a uniform flavour in the final product. Here liquid spice extracts (page 84) are best suited as solid spice particles can cause blockage of injection needles. Other common additives in the curing brine solution are cure accelerators and phosphates. The common cure accelerator used in cured-cooked meat products is sodium ascorbate. The use of ascorbic acid must be avoided (page 174). Sodium ascorbate (0.1-0.2%) should only be added to the curing brine immediately before application, as otherwise the substance could initiate a premature breakdown of the nitrite.

Other additives used in small amounts include sugars. In only mildly pasteurized products sugar might cause undesirable acidity during prolonged product storage, due to active Lactobacillus bacteria. The addition of phosphates, especially in combination with salt, increases the water binding capacity of raw meat and contributes to improved texture in the final product after heat treatment (see Fig. 230). In low-cost products with increased yield (reconstituted hams), additional non-meat additives can be used, such as isolated soy protein, and modified starches. In these rather complicated curing brines, care must be taken that all additives are completely dissolved and evenly distributed.


Table 11: Approximate addition to curing brines for injection1
(referring to 15-25% brine injection)

Additives

% in brine

Curing salt

8 - 14

Phosphate

1 - 3

Sodium ascorbate

0.15 - 0.20

Isolated soy protein

4 - 6

Sugar

1 - 4

Gelatine

1 - 2

Carrageenan

0.5 - 2

Modified starches

1.5 - 3

Glutamate

0.2 - 0.3

The following sequence is commonly recommended for the successful preparation of curing brines (Fig. 223, 224, 225):

Fig. 223: Preparation of common curing brine (containing curing salt and phosphate)
Correct order of dissolving components
1 = Add phosphates first, 2 = Stir and dissolve, 3 = Add nitrite curing salt,
4 = Stir and dissolve, spice extracts can be added at this stage,
5 = Brine ready for application


Fig. 224: Wrong order of dissolving components for curing brine (leads to clotted phosphate) (phosphate must be dissolved first!)


1) There may be variations involving a wider range than indicated in table 11 depending on local processing techniques and national regulations.



Fig. 225: Correct order of dissolving ingredients in complex brines
1 = phosphate, 2 = isolated soy protein, 3 = curing salt, sugar, gelatine and carrageenan, 4 = modified starches and sodium ascorbate

To reduce bacterial contamination of the cured meat, particularly through injection, curing brines must be hygienically prepared and handled. For example in case of poor hygienic water quality, the water used for the curing brines should be boiled and thoroughly chilled again before application. This can be achieved by either cooling the potable water in the cold room, or by direct addition of ice (use of ice water). When using ice, care must be taken that it has completely melted prior to injection of the curing brine. Large portions of remaining solid ice, into which no salt penetrates, would result in too high a salt concentration in the liquid part of the brine. The temperature of meat and brine should not exceed +4°C. One important additional benefit of such low temperatures is the increased amount of protein going into solution, thus contributing to improved water holding and reduced cooking loss of the final products.


Whole muscle products


Fig. 226: Manual brine injection

Curing brine injection (see page 39) is the method of choice for a fast curing process of large meat cuts (entire pieces of muscle meat) to be processed through curing and subsequent heat treatment. The curing brine solutions are injected into the muscle tissue by using either manually operated curing brine pumps with a single or multi-needle device (Fig. 226) or automatic multi-needle brine injectors (see page 27, 39). The curing brine injection should take place in small quantities and repeatedly in various different spots of the muscle tissue. Injection of huge quantities of brine in one or few isolated spots would cause ruptures of the meat tissue and substantial loss of brine. Usually 15-20 % of brine (by volume) having a salt concentration 10-14 % are injected into. Both parameters need to be carefully balanced in order to achieve the desired salt concentration in the final product, which are normally between 1.8% and 2.4%, depending on the product type.

The equipment used for the curing brine injection (pump, hoses, needles) must be thoroughly cleaned and periodically disinfected to prevent the transfer of microbial contamination from dirty equipment into the meat.

Excessive pressure during brine injection or the injection of larger quantities of brine into one spot must be avoided, as both would damage the meat tissues. Muscle pumping, even if done properly, may still result in unequal distribution of the brine throughout the meat cuts. For this reason the curing is usually completed by immersing the meat in curing brine of the same composition as the one injected (“resting period”). This method has the advantage that losses of injected curing brine are replenished.

The “resting time” for products, which are not tumbled, should be 24-48 hours under refrigeration. This will further enhance the uniform distribution of salt and curing substances and ensure the development of an attractive red curing colour throughout the meat cuts prior to cooking.


If tumbling equipment (see page 28, 184) is available, the immersion of the meat in brine (“resting period”) is not necessary. In this case, the drip-off of brine lost during injection is added to the tumbler and will be reabsorbed by the muscle tissue during tumbling.


Fig. 227: Filling meat pieces in casing and putting in mould before cooking

The curing colour is further stabilized during the first phase of the subsequent heat treatment, while passing through the temperature range of 30-50°C. Large cured meat cuts (e.g. boned pork legs) can be kept in the desired shape by tightly binding them with layers of string. In recent years this labour-intensive method has been increasingly replaced by using expandable nets. These more traditional products are often hot-smoked prior to cooking in steam. Alternatively, the meat cuts can also be tightly pressed into ham moulds, round or square (Fig. 414), or stuffed into heat resistant plastic bags or casings and cooked (Fig. 227).

Reconstituted meat products of the cured-cooked type

Cured-cooked meat products can also be produced from smaller muscles or muscle parts (Fig. 228, 229). These smaller size meat pieces are usually derived from meat cutting and grading operations. The main purpose of these procedures is cost reduction, as carcass parts can be more profitably utilized. The most common source is pork meat, mainly hind legs, shoulders or loins are de-boned and dissected. The dissection enables grading according to lean and fat, dark or bright meat colour and even according to the pH of individual muscle tissues.

The selected smaller muscles or muscle parts undergo preparatory treatments. Care must be taken that all fat and connective tissue layers are removed from the meat surface. These undesired tissues are either removed manually or by using electrical “skinning” machines. The lean surfaces of the muscle pieces should be incised by knife, as this, in combination with the application of curing brine, facilitates the release of liquefied muscle protein, which in turn coagulates during heat treatment and makes the meat pieces stick firmly together.


In the next step, the smaller muscles or muscle parts are injected with curing brine and subjected to a resting phase of 24-48 hours. Cure accelerators, phosphates, and spices are added to the curing brine as described in sub-chapter “Whole muscle products” (page 182). The cured meat pieces are then tightly pressed into ham moulds and cooked. To facilitate the necessary firm coherence of the meat pieces, some meat processors sprinkle small quantities of gelatine powder onto the meat surfaces to be bonded together.

The release of liquefied muscle protein in particular on the surfaces of meat pieces can be further enhanced by subjecting the brine-injected or brine-infiltrated meat pieces to tumbling. Tumbling is the mechanical treatment in special equipment, either in rotating drums with fixed massaging humps or in fixed drums with rotating massaging arms (see also page 28 and Fig. 228). Tumbling takes place at temperatures of <4°C (-5 to -8°C is best) for several hours (up to 24 hours) (Fig. 229). Tumbling or massaging followed by heat treatment allows the meat processor to reconstitute larger and uniformly shaped cured-cooked meat products from smaller meat pieces of different sizes and shapes. At the industrial scale large quantities of such products are manufactured.


Fig. 228: Tumbling of pork pieces, brine added to tumbler


Fig. 229: Pieces of pork after tumbling

Apart from the above processed goods the use of a tumbler enables production of low-cost cured-cooked products. Lean meat pieces and trimmings from all parts of the carcass are coarsely ground, placed in the tumbler together with the desired quantity of curing brine and tumbled/mixed. Such products very often contain non-meat additives for cost reduction and improvement of the binding and water holding capacity of the mixture, such as soy protein (isolate), hydrocolloids (carrageenan), gelatine, transglutaminase, etc. (see page 71, 80).

In general, in order to facilitate a timely and uniform tumbling/curing process, larger meat pieces are brine-injected prior to tumbling, while smaller pieces can go uncured directly into the tumbler. Care must be taken that the correct quantity and concentration of curing brine is added. Amounts and concentrations of brines must be carefully balanced in order to maintain the targeted salt content of the final product, which should be in the range of 2% (see also table 12).

Table 12: Treatment for cooked cured products

Brine injection

Treatment after injection

Heat treatment of products in containers (moulds, foils, etc.)

Entire meat pieces

Brine 15-20 % by volume with a a salt conc. of 10-14%

Temperature 0°C

Resting period for penetration of curing salts (12-26 hours, 0-4°C), with or without tumbling

Water/steam

Temperature 70-75°C

Internal temp 70 (72) alternatively: hot smoke for bacon, pork chops

Small pieces to be reconstituted

Brine by 15-20 volume %

with a a salt conc.. of 10-16% Temperature 0°C

Tumbling for equal distribution of all ingredients, 8-12 hours (15 min. tumbling, 15 minutes rest) (0-4°C or below)

Water/steam

Temperature 70-75°C

Internal temperature 70°C (72)



Fig. 230: Entire cooked ham (left) and tumbled reconstituted cooked ham (right)


Fig. 231: Beef ham as a cured-cooked product, made of one entire piece of muscle

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