Kanza Saeed Lecturer Department of Food Science and Technology KFUEIT

▪ Evisceration ▪ Plucked birds will have been rehung either manually or automatically on the evisceration line. ▪ They then pass through a number of automatic carousel machines, which will perform the operations necessary to eviscerate the bird and present a clean carcass to the chilling process. ▪ In sequence these operations are venting and opening to open up the bird for evisceration, evisceration itself during which the viscera pack and all edible and inedible offal are removed, neck flap cleaning to ensure that the trachea and oesophagus have been removed from the neck skin, automatic neck removal and the removal by vacuum of any loose debris still remaining in the carcass. ▪ Once all these operations have been completed, the carcass is given a thorough wash both inside and out.

▪ Until some ten years ago eviscerating machines drew out the viscera `pack’ and laid it over the back of the bird, from where all edible giblets were harvested. This process can still be seen in many smaller plants. ▪ New evisceration systems were then launched, which drew out the viscera pack and then transferred it automatically to an entirely separate giblet harvesting process. ▪ These newer systems saved labour and improved hygiene in that the viscera pack no longer came into contact with the back of the bird thus reducing contamination with gut contents. They also made veterinary inspection of both bird and viscera pack easier.

▪ In many markets edible giblets such as hearts, livers and gizzards remain valuable whether for sale for human consumption or for the manufacture of pet food. ▪ It is therefore important that as many giblets as possible are harvested. ▪ In some cases the neck is packed with the giblets. ▪ Modern evisceration systems separate the viscera pack completely from the bird and either deposit it into a synchronised pan conveyor for semi or fully automatic giblet harvesting, or transfer it to a synchronised overhead conveyor system, where individual machines cut off the intestines and gall bladder, harvest the liver, deposit the gizzard into a gizzard processing system and drop the heart and lungs into a heart and lung separating machine. ▪ Advantages of the new process are substantial labour savings, increased giblet yield and vastly improved hygiene.

▪ Giblets can be chilled by cold air or by immersion in counterflow water chillers. ▪ They can be pumped either before or after chilling to a separate area in the processing plant for further handling and packing. ▪ Alternatively they can be packed into crates in the evisceration department and then air chilled. ▪ A new technique involves giblets being deposited automatically onto a belt conveyor system, which takes them through the same air chiller as that used for carcasses. ▪ Once chilled these giblets are packed for sale, retail or bulk. ▪ Inedible offal such as intestines, lungs and waste from the gizzard harvesting process is usually sucked away in a fully enclosed vacuum transport system, which deposits thematerial into storage containers for subsequent removal from site.

▪ Once evisceration is complete, birds must be chilled to slow the growth of harmful bacteria. ▪ How carcasses will be sold, whether in whole carcass, portioned or deboned meat form, will determine the chilling process to be used. ▪ If carcasses are to be sold dry and fresh, they will have been soft scalded and will be chilled using air alone. If they are to be sold wet fresh or frozen, they will have been medium or hard scalded and must be wet chilled. ▪ Medium or hard scalding removes most or all of the outer epidermis. ▪ If such carcasses were air chilled, they would emerge from the process unacceptably discoloured.

▪ This involves circulating cold air around and inside the carcasses, taking care, however, not to freeze wing tips and neck flaps. ▪ Most higher capacity plants producing dry fresh product will have an air chilling tunnel, through which birds are transported by shackles on an overhead conveyor system, which can be up to four tiers high ▪ Cold air is blown either down onto or across the carcasses. ▪ Such tunnels are known as `downflow' or `crossflow' tunnels. ▪ Some tunnels also have a system of ducts, which direct cold air into the cavity of the carcass and over the thickest part of the breast.

▪ This method shortens the chill time needed. ▪ In all cases birds are chilled to a maximum of 4C, a process that takes 1.5±2.0 hours for a 1.5±2.0 kg carcass. Birds can be transferred automatically to and from the air chilling line. ▪ Air chilling techniques are also used in maturation chill tunnels. ▪ One disadvantage of air chilling is that carcasses can dry out resulting in yield loss. ▪ Moistening techniques are now available, which largely prevent carcasses drying out and which have no negative effect on shelf-life.

▪ The two most common methods of wet chilling are water-immersion chilling which is usually carried out in a counterflow screw chiller and spray chilling. ▪ Whilst water-immersion chilling has disappeared from most European Union countries, it is still common practice in many other markets in the world. ▪ The process involves dropping carcasses into a one- or two-bath system, through which they are transported by an Archimedes screw into ever colder and cleanerwater. ▪ Agitation of the chill water allows carcasses to pick up water to the maximum allowed by national legislation. ▪ In the EU, the process must meet requirements relating to water usage and temperature and carcass residence time. ▪ Immersion chilling is more labour intensive than systems using an overhead conveyor, as automatic line-to-line transfers cannot be installed.

▪ Spray chilling is common in the European Union. ▪ In essence this technique involves adding a system of water sprays to an air chilling tunnel. ▪ Carcasses are chilled `individually' on a shackle. ▪ Evaporation of the water film on the carcass surface may assist the cooling process, while wetting the carcass avoids excessive moisture loss. Water pick-up is, however, less than with an immersion chill.

▪ In some markets wet and dry processes are combined to give a composite system. ▪ An example of this is a shortened immersion or drag through wet chill system followed by a shortened air chill tunnel. ▪ Medium or hard scalded carcasses remain wet but do not have the same amount of free water as birds chilled completely by immersion.

▪ Carcasses can be graded for quality by specially trained personnel. ▪ Grading can be carried out before or after carcasses are hung to the preselection line. ▪ Various devices are available for registering the quality grade allocated to each carcass. ▪ These pass this information to a computerised control unit, which will also receive and process data on the weight of each carcass. ▪ Some plants now use computer-controlled vision systems, which assess quality automatically.

▪ Carcasses are weighed electronically either in the rehang unit, which transfers them from the chill line to the preselection line, or in a weigh station installed in the preselection line itself. ▪ This information is passed to a computerised control unit.

▪ Information on weight and quality is processed in the computerised control unit and each carcass allocated by weight and quality grade to a number of automatically activated unloading stations or to one or more automaticportioning systems. ▪ Modern control systems allow individual customer orders to be met in the most cost-effective way and will integrate easily into higher computer systems.

▪ How whole-carcasses will be packed will depend largely on whether they are to be sold fresh or frozen. ▪ Wet chilled carcasses to be sold frozen are usually packed into pre-printed polythene bags. ▪ This can be done manually using bagging chutes or either semi or fully automatically using a range of bagging and closing machines. ▪ Dry chilled birds to be sold fresh are usually placed onto trays and overwrapped with film. ▪ They are then weighed and labelled. ▪ Bags or other leak-proof packaging systems can be an alternative. Carcasses to be further processed or sold wholesale are usually packed in bulk into cartons or returnable plastic crates.

▪ All products that will be sold fresh rather than frozen require further chilling to slow the growth of cold-tolerant spoilage organisms. ▪ This is usually acheived by holding the wrapped product in a chill room until the deep-muscle temperature reaches 0±1C.

▪ In high volume markets, a large percentage of carcasses is cut into portions for retail sale, for use in canteen and catering outlets and as a raw material for an increasingly wide range of fast-food products. In low throughput plants carcasses can still be cut manually. ▪ In most medium and high throughput plants, however, birds are cut automatically by modular systems able to operate at hourly throughputs of 5000 carcasses or more.

▪ Most automatic cut-up systems are now installed on overhead conveyors, which allow cutting modules to be sited at any point on the conveyor. ▪ This makes for optimum layout flexibility helping to ensure the best possible logistics in the cut-up and deboning area. ▪ It is, of course, vitally important that the product is packed as quickly as possible and transferred to the chill store or freezer. ▪ Automatic cut-up systems are now able to replicate with great accuracy virtually all portion cuts currently in everyday circulation. ▪ They are also able to weigh and size in-line whole and half carcasses, rear quarters, anatomic legs and drumsticks.

▪ A relatively recent innovation is the ability to track carcasses electronically through the cut-up system and to by-pass individual cutting modules. ▪ When combined with weight information from the preselection line or from one or more weighing modules in the cut-up system itself, this ability allow carcasses to be cut selectively and extremely cost-efficiently according to weight and to orders received by the processing plant from its customers. ▪ The same technique allows legs, for example, to be sized into whole leg portions, cut into thigh and drumstick portions, or transferred automatically to an automatic leg deboning line.

▪ More and more carcasses are being deboned to satisfy the rapidly increasing demand for deboned meat for use both at home and in the preparation of an ever wider range of further processed convenience and catering products. ▪ Whilst many lower volume plants still debone by hand, labour cost and availability will often dictate that deboning is done automatically. In many markets breast fillet is the premium product. ▪ The first machines to debone these automatically were launched in the early 1980s. Modern modular systems can now handle in excess of 3000 breast caps or front halves per hour and can process these into a wide.

▪ variety of breast fillet products both with and without skin. ▪ The systems, which can be integrated seamlessly with downstream weighing and packing activities, give excellent yields with minimal residual bone and can be switched quickly from one fillet product to another. ▪ Whole legs, thighs and drumsticks can now also be deskinned and deboned automatically. ▪ These activities can either be carried out in stand-alone machines or in modular overhead conveyor based systems, to which pre-sized legs are transferred automatically from the automatic cut-up system. ▪ Leg deboning can be performed at speeds of up to 7200 legs per hour.

▪ Product for sale retail can be packed in a number of ways. ▪ Portions to be sold frozen will usually have been individually quick frozen in a spiral freezer. ▪ These are then often packed by weight into pre-printed polythene bags. ▪ Portions, including breast and thigh fillets to be sold fresh will usually be packed on trays, overwrapped, weighed and labelled. ▪ In some markets, however, where packs are sold by weight and count, sophisticated weighing systems will assemble the required pack weights automatically and with a minimum of give-away, before the product is packed.

▪ In recent years large supermarket groups are attaching increasing importance to modified atmosphere packaging techniques. ▪ Packing portions of deboned meat in a modified atmosphere environment prolongs shelf-life and gives both processor and retailer increased operating flexibility.

▪ Grading carcasses and portions for quality has always been a key activity. ▪ Until relatively recently this was performed by eye. Some ten years ago the first in-line computer controlled vision systems began to come onto the market. ▪ Although initial progress was slow, vision systems have now become commonplace in today's high volume processing plants ▪ The first systems were installed to grade fresh birds in-line after air chilling. ▪ Advantages were labour savings and, perhaps even more importantly, more consistent grading. ▪ Accurate grading is essential if the best use is to be made of each individual carcass. ▪ The latest systems are now able to grade birds in-line immediately after plucking and either before or during automaticportioning to grade individual parts of the carcass such as wings, breast, thighs and drumsticks. ▪ Grading birds after plucking pinpoints the exact reasons for any downgrading and will reject unfit carcasses. Grading individual parts of the bird saves labour and allows the best use to be made of each individual portion. ▪ Work is also being carried out on using vision systems to detect disease on both the killing and evisceration lines.

▪ Maturation off-line in a maturation store has a number of disadvantages. ▪ A process or combination of processes was therefore needed, which would allow birds to mature in-line to give the tender breast meat which consumers want. A process is now available, which allows the same levels of tenderness to be achieved in-line in some three hours as were formerly only possible by storing birds off-line for at least six to eight hours. ▪ This process comprises a cocktail of measures to accelerate both rigor mortis and the breakdown of proteins: ▪ · controlled atmosphere stunning ▪ · electrostimulation ▪ · maturation chilling.

▪ Controlled atmosphere stunning has been shown to help the tenderizing process. ▪ In-line maturation is, however, also possible with high frequency electrical stunning. ▪ Electrostimulation, which accelerates rigor mortis, has already been referred to above and can give in just 90 seconds the same tenderising effect as maturing carcasses off-line for some four hours. ▪ The final element in the process is in-line maturation chilling in a maturation chill tunnel. ▪ The maturation chill tunnel is a variant of a standard air chilling tunnel, where the chilling process is carried out in two phases. ▪ In the first, shorter phase all exterior and interior surfaces of the carcass are chilled rapidly using very cold air at high velocities.

▪ The application of a thin water film prevents birds drying out and helps the chill process. ▪ In the second, longer phase birds are subjected to less cold air at much lower velocities. ▪ This promotes maximum enzyme activity to break down proteins. ▪ Maturation in-line gives the following benefits: · saves labour as it eliminates double handling · improved hygiene as product is touched less · saves space and improves logistics · reduces weight loss · helps traceability · prolongs in-store shelf-life

▪ In recent years food safety has become a hot topic. ▪ Many retailers and fast food chains now insist on complete traceability for their products. ▪ In those plants where birds are kept on-line from live-bird hang-on to their release as sized whole-birds or portions, and where transfer between the individual processing lines is carried out automatically, it is now possible to track each individual bird through the entire process and thereby to guarantee traceability.

▪ Birds are tracked by counters linked to a central control system, which will also interface with in-line weigh heads, quality grading devices and vision systems. ▪ This allows a complete `file' to be kept on each bird with full information on which growing farm it came from, how much it weighed after processing, what quality grade was assigned to it, for what type of end product it was used and to which customer it was despatched.