Processing of the chicken includes all the steps used for conversion of live birds to dressed chicken and its retail cuts include several steps. All the operations should be carried out in hygienic manner to produce wholesome and good quality meat.
Considerations during slaughter
- Humane Slaughter: The bird should be slaughtered in humane way. Bird should get adequate rest and provide ample water before slaughter. If permissible, stunning must be practiced to avoid pain to the bird and the bird should be bled with sharp knife. The main objective of humane slaughter is to expose the animal to minimal pain and stress.
- Adequate inspection: Adequate inspection includes ante- mortem and post-mortem inspection. Birds found unfit in ante-mortem inspection should not be allowed for slaughter. Similarly, carcass and viscera with abnormal findings should not be passed for human consumption without approval from competent authority.
- Complete bleeding: It is impossible to drain out whole blood, whatsoever the method of slaughter is followed. ‘Halal’ method is considered superior to ‘Jhatka’ as far as bleeding is concerned. Stunning is supposed to improve efficiency of bleeding.
- Hygienic evisceration: Evisceration and separation of edible and inedible viscera should be carried out in most hygienic way.
- Utilization of by-products: The profit of commercial poultry plant depends on the fact how much efficiently it utilizes by-products. This section must take care at the time of planning the project layout..
Modem poultry processing will bring about the much needed sophistication to the poultry industry. Essential steps involved in the processing of chicken are detailed here.
Reception of Birds
Before slaughter, birds have to be collected from the farm and prepared for slaughter. Withdraw the feed at least 6-8 hours before slaughter but adequate drinking water must be provided. Fasting serves to partially empty the digestive tract, a requirement to avoid contamination during dressing. Again, hydration to body improves bleeding and quality of meat. Generally, birds are caught by shanks. They are usually loaded in the crates at night for transportation from farm to processing plant. Care should be taken to avoid injury to the bird during loading and unloading to avoid bruises and broken wings. Then birds are weighed. At large plants, birds are unloaded onto conveyor belts.
Ante mortem examination
The common process by which the live poultry are judged in the market is by feeling the pliability of the posterior portion of the breast by fingers. In case of young birds it can be readily bent whereas in case of old ones it is hard and resistant.
- Extreme emaciation.
- Obvious evidence of diseases such as abdominal accumulations in the form of fluids or cheesy substances, numerous extensive or repulsive growths inside the carcass, inflamed and reddened linings of body cavity.
- Severely bruised carcasses, etc.
SLAUGHTER AND DRESSING OF POULTRY
It is advisable to stun the birds before slaughter for humane killing and to improve meat quality. Stunning methods are given below:
- Electrical shock using a water bath stunner with a voltage range from 60 to 110 volts.
- Immobilization by carbon dioxide.
Generally, stunning by 50 volts AC for 1 minute (electric stunner) is followed. Stunning speeds up the heart rate which gives a more complete bleeding and the birds become quiet. The muscles are also relaxed and feather removal is easier.
Killing and Bleeding ‘
The most convenient method of slaughter is to cut the throat so that jugular veins and carotid arteries are severed to ensure complete bleeding.
Jhatka or Halal method of slaughtering is also practiced.
In ‘modified kosher method’ where trachea and esophagus are not cut, only jugular veins are severed just below the jowls. In all the cases, bleeding is good if birds are hanged with shackle.
Improper bleeding may lead to following conditions:
- Lowered keeping quality of carcass.
- Undesirable flavours.
- Unpleasant appearance of the carcass due to blood showing in the capillaries on the breast, veins on the neck, shoulder, wings and over thighs.
- Entire bird may look reddish even in chilled, frozen and thawed condition.
Birds are dipped into or sprayed with water at controlled temperature and for specific time. Scalding apart from facilitating defeathering, improves appearance of skin.
Types of Scalder
a. Spray type – Hot water is sprayed/poured over the birds moving on the line. It keeps the water clean.
b. Dip type – Tank type scalder with thermostat control is used. Water is not so clean as compared to spray type.
Types of scalding
- Hard scald: Birds are dipped in hot water of temperature 62-64°C for a period of 30-60 seconds. The method has its own advantages and disadvantages.
Advantages: Feather removal is easier and it is suitable for poultry that is to be canned immediately. Generally used for ducks and geese.
Disadvantages’. Muscles in feather follicles are cooked. It destroys the protective covering of the skin, thus bacteria may enter. It results into lowered keeping quality of bird. Bird appears blotchy when it is dried up. So it causes undesirable discolouration of skin. Because of these disadvantages, hard scalding of poultry is generally not practiced. Moreover the method is not economic for commercial purpose.
- Sub scald: Here birds are dipped in hot water of temperature range 58-60°C for a period of30-75 seconds. Associated advantages and disadvantages are as follow:
Advantages: Useful for turkeys and feather removal is easier than semi-scald.
Disadvantages: Cuticle is removed, i.e. breakdown of the structure of the outer layer of skin. It permits more rapid loss of moisture. Skin surface becomes sticky to touch on drying. Here also cost of water heating is more.
- Semi Scald: It is also known as Soft Scalding or Slack Scalding. Here birds are exposed to hot water of temperature 51-54°C for a period of 90-120 seconds.
Advantages: Cuticle is not removed (epidermal layer). Pigmentation or original skin colour and bloom are retained. It retards dehydration and spreads the fat beneath the skin. It also prolongs the shelf life. It is considered optimum for commercial adaptability.
- Combination of Methods: As the name indicates here more than one of the above mentioned temperatures is used subsequently for a short time span. The tough portion of neck and back feathers are removed second time by exposing the bird for a period of 30-75 seconds to a temperature range of65-70°C in case of turkeys and 60-62°C in case of poultry.
Poultry pickers are being extensively used for removing feathers. Ensure that picking is done immediately after scalding. You may follow the following methods of picking:
- Hand Picking: Tail feathers, wing feathers and body feathers are removed by hand.
- Machine Picking: The feathers are removed by mechanical picker. The machine removes the feathers by abrasion.
i A drum picker i.e. a cylinder with rubber fingers around the exterior can remove the feathers of one bird at a time. The operator holds the bird against the cylinder.
ii. Batch picker i.e. a rotating tub with rubber fingers in inside wall can handle
2-12 birds at a time.
In-line pickers are used at large plant. In conveyor line picking is done automatically. It looks like a tunnel with rubber fingers. Birds are hanged by shackle and passed through the tunnel.
- Wax Picking: Rough picked bird is coated with hot wax. When the wax is cooled, feathers are removed. It is not in practice. Pin feathers, hair and foreign materials are removed cleanly from the skin by wax. It is suitable for ducks and geese.
Stump of feather is called pin feather, which must be removed completely to improve the appearance of the carcass. Pin feathers can be removed either by hand or with a pinning knife (a knife with a short blunt blade).
Singeing refers to the removal of hair like feathers (filoplumes) by means of a flame. After pinning, the hair on the body are removed over a singer on the line or a blowlamp by rotating the carcass over the flame. Singeing also causes the destruction of surface microbes and improves appearance and colour of the carcass.
Removal of Head, Oil Gland and Feet
Defeathered bird is washed and then head is cut-off at small plant. At large plant, head is mechanically pulled-off so that esophagus is also removed. Oil gland which is situated on top of the tail results in typical odour to the carcass. That’s why this gland is removed. The feet are cut-off at the hock joint by knives, saws, manually operated shears or mechanized shears.
Venting is performed on defeathered carcass by pressing on the abdomen just below the vent for the purpose of removing faecal matter, which may still be in the lower intestine. The carcass must be washed immediately after venting and before the viscera is drawn.
In modern processing lines venting is done by cutting around the vent region.
Birds should be eviscerated as quickly as possible after slaughter on the line while birds are still warm. Stationery shackle or a table with stainless steel or metal top is used for reasons of sanitation in hand dressing. When the birds are eviscerated manually, a cut is made around the vent with a sharp knife. The operator holds the carcass firmly in one hand and draws the organs by a drawing tool placing through the cut. The inedible viscera or guts i.e. intestines, esophagus, spleen, reproductive organs and lungs are kept in offal bin. The liver, heart and gizzard are placed in appropriate trays for further processing. These three organs are known as giblet. As the kidneys are hard to remove, they remain inside. A small slit is made on the back of the neck to remove the crop and trachea. The evisceration is followed by washing and inspection. The mechanical evisceration followed in modem plant will be discussed under the heading of automatic plant dressing line.
After dressing, the carcass should be scrubbed and washed well with fresh, clean water. Processors wash the carcass at different points but the most common point of washing is before chilling. Processors may also add chlorine to water as to reduce bacterial load of the carcass. The edible viscera are also cleaned and washed properly for inspection.
Post mortem Inspection
Internal surfaces of the abdominal cavities, along with the visceral organs are examined and carcasses with abnormalities are rejected. Inspector must be a veterinarian or a person trained to do this work.
Birds with following diseases wherein, the entire body system has become affected will have to be rejected:
Tuberculosis, septicaemia, leucosis, tumors, inflammation, toxemia, botulism, erysipelas, mold infections, fowl cholera, fowl typhoid and paratyphoid, puHorum disease, coryza, laryngotracheitis, fowl pox, trichomoniasis, black head and coccidiosis etc.
If only a localized area is affected, it may be removed and remainder of the carcass is retained. Birds showing decomposition should be destroyed. A slippery or slimy condition of the skin, especially between the wings and the body, a greenish cast over the back and between the thigh and the ribs, mold growths anywhere on the bird, a putrid off-odour, will all result in the condemnation of carcasses.
Trussing: In some plants trussing is followed. Trussing refers to the fastening or securing wings and legs to the body with a view to give a more compact and attractive appearance to the carcass. Trussing results in greater ease of packing. The following steps are required for trussing. The neck skin is drawn as far over the back as possible and the wings are locked over the back to hold the skin in place. The legs of bird are secured under the fold of skin below the keel. The bird is then ready for chilling
Chilling poultry immediately after processing is an important requirement for maintaining quality.
Ice chilling is most often used. Chilling tanks or vats are used for this purpose. Only crushed ice produced from wholesome water or block-type ice which has been sprayed with clean water and crushed should be used. Enough clean water and ice is provided in the chilling tank to maintain a temperature of 2-4°C all the times. The carcasses should be cooled to 4°C or below within 4 hours. Thumbing/agitating chill tank reduces chilling time to about an hour. The water used for chilling is chlorinated to minimum level of 50 ppm. Approximately 2 kg ice is required for cooling of one bird. Normally the carcasses take 20-3 0 minutes to cool. Occasionally the carcasses should be moved by hand through the cooling medium to ensure that no bird is left in the chilling tank for too long.
Air chilling is more suitable for fresh dressed chicken and semi scalded chicken so that the epidermis is left on carcass and discolouration is avoided. However industry favours wet chilling due to gain in weight and juiciness. In dry/air chilled birds, there is some dehydration and dryness. You would be learning in detail about chilling and freezing of poultry later in the next block.
Chicken can be sold as whole carcass as well as cut up parts. After chilling the dressed chicken may be cut into two halves longitudinally or quartered. For tray packaging, chicken carcass may be split to 2 wings, 2 legs, breast, backs and neck. The giblets consisting of heart, liver, gizzard, along with neck are packed separately and placed with full cut up chicken. In sophisticated market one can buy individual cut-up parts such as wings, legs, breast, back and neck. The breast and wings are light meat and fetch premium price. In developed countries legs are not normally consumed as it is dark meat with considerably more fat and not lean as compared to breast meat. Deboned chicken meat is sold at premium price.