Portion control is an important concept in food service, the segment of the food industry known as the hotel, restaurant, and institutional industry (HRI). This segment has been growing rapidly in response to the increasing trend of the U.S. consumer eating more meals away from home. Portion control is an attempt to have uniform portion size, appearance, and quality so that each customer gets the same amount of food, there is less picking from a buffet line (leaves extremely large and small portions behind), and it allows more accu- rate food supply and cost projections. Portion control is also important in retail food mar- keting because the home consumer prefers uniformly sized portions because of their cooking (time, endpoint temperature, method) and serving (appearance, doneness) con- sistency.
The production of cut up parts was helped by the natural suitability of each part as an individual meal portion. This is particularly important in the fried chicken restaurant industry in which each piece needs to have approximately the same amount of meat so that each customer gets the same amount of product, regardless of the part they eat. This was partially the origin of the nine-piece cut. The breast of the commercial broiler was a dis- proportionately large proportion of the carcass and was therefore not an appropriate
portion size relative to the other pieces. The solution was to cut the breast into three pieces, and to cut the wing off so as to include some of the breast meat on the wings. This distrib- uted the carcass more evenly to all the component pieces. Further control of portions is usually obtained by sorting the carcass by weight into ranges specified by the customer. This results in all the parts of a given type (e.g., thighs) being about the same size. The scales for this weighing are usually in line with the overhead shackle line. When the shackle containing a bird of the desired weight passes over the scale, the carcass is released into a bin for cutting into parts. It should be noted that portioning could also begin with live bird. Most processors will use specific genetic strains and/or slaughter birds at a spe- cific age to produce the largest percentage of their birds in the range specified by the cus- tomer.
Because of its high value and specialized uses, boneless breast meat is portioned in many different ways. The first thing that can be done is to trim off the connective tissue, membranes, and fat from the edges. This intricate operation is still done manually in most cases (Figure 4.5). Depending on the amount of muscle tissue this trimmed material (or “trim”) contains, it can be used in some restructured product like a nugget or patty. Certainly, this trimming is a way of adding value to the fillet because it is a convenience service that reduces customer waste and increases uniformity of the product. The price increase for a trimmed fillet will be enough to cover the added production expense plus the profit associated with the added value of convenience. After trimming, the fillets can be sorted according to weight. The fillets pass down a high-speed conveyor and over a series of scales, each scale set for a specific weight range. When the fillet crosses a scale set for that fillet’s weight, the scale signals a computer to use a lever to push the fillet into a bin. The computer can also keep track of productivity and inventory as it gets a signal for every fillet.
B
Figure 4.4 (A) Postmortem electrical stimulator in a broiler processing plant. (B) Closer view of elec- trical stimulator showing contact of birds’ heads with the charged plate.
More refined portioning can be achieved by cutting the fillet into smaller pieces with vertical or horizontal cuts. A specific length, width, and height can be created with combi- nations of these cutting procedures. The vertical cuts shape the length and the width of the piece. This can be done by hand or more quickly by a machine. The machine uses a camera and computer to create a digital image of the fillet passing by on a conveyor. Using the specification for the desired size of the portion, the computer determines the best way to cut the fillet. It then directs a cutting device to make the cut. These devices usually use water knives, which are highly focused, high-pressure sprays of water. These jet streams of water easily cut through the soft muscle tissue. Frequently, the center is the premium part of the fillet, with the outer edges used with other trim in restructured products.
The horizontal cut controls the thickness of the fillet and is sometimes called a “slitter” cut. For this cut, the fillet rides between two plates or conveyor belts toward a horizontal blade or water knife (Figure 4.6). The plate or the second belt immobilizes the fillet as the knife cuts it. The distance between the blade and the belts or plates determines the thick- ness of the resulting fillet, and is set according to customer specifications. The portion of the fillet possessing the original outer surface of the muscle (away from the sternum) is
Figure 4.6 Schematic diagram of a “slitter” machine showing opposing conveyor belts and product being cut.
the premium piece because it most resembles the original muscle. Although a chicken fil- let is only slittered once, a turkey fillet can be slitter cut multiple times because of its greater thickness.
A final way to control the dimensions of the fillet is to flatten it through a process called “bridging” or “cubing.” The fillet passes between two closely spaced rollers that have knobs protruding from their surfaces (Figure 4.7). The fillet is squeezed between the rollers, reducing its thickness and increasing its length and width. The knobs puncture the epimysial connective tissue layer, increase surface area for marinade absorption, and improve tenderness by physically disrupting the muscle structure.
In addition to size, color is another uniformity concern for poultry processors. Genetics, preslaughter heat stress, and chilling rate have all been associated with paleness and reduced water-holding capacity.11–14Some processors are sorting out the pale fillets from further processing because their poor functional performance can cause variation in product quality. Pale, soft, and exudative (PSE) and dark, firm, and dry (DFD) are both abnormal meat color conditions related to muscle metabolism.4Variation in meat color is also important to skinless, boneless breast meat in retail packages.15,16In addition to PSE and DFD meat, the concentration of muscle pigment proteins like myoglobin and blood pigment proteins like hemoglobin can alter meat color. Because there are usually four or more fillets displayed side by side in a package, variation in one or more fillets is very obvious and leads to rejection of the entire package by consumers. Many processors sort the fillets by color and only package uniform appearing units together.
Summary
In contrast to the first processing area of the plant, second processing involves a consider- able amount of manual labor to perform the intricate cutting, trimming, and portioning. However, second processing is where much of the value is added to the profit and there- fore where most of the plant’s profit is derived. Production of parts and boneless breast meat are the major functions of modern processing plants and are excellent examples of adding value to the processed carcass. Portion control is a growing segment of poultry pro- cessing because poultry carcasses are more easily made into consumer-ready portions of Figure 4.7 Schematic diagram of a “bridging” (or “cubing” or “flattening”) machine showing op- posing rollers with flattened meat.
parts and boneless fillets than other meat types. It should be remembered that when a cus- tomer pays more for a premium product, they are also expecting a premium level of qua- lity and consistency. That is to say that their “quality sensitivity” is very high.
References
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6. Nakamura, R., Sekoguchi, S., and Sato, Y., The contribution of intramuscular collagen to the tenderness of meat from chickens with different ages, Poult. Sci., 54, 1604, 1975.
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11. McKee, S. R. and Sams, A. R., The effect of seasonal heat stress on rigor development and the incidence of pale, exudative turkey meat, Poult. Sci., 76, 1616, 1997.
12. McKee, S. R. and Sams, A. R., Rigor mortis development at elevated temperatures induces pale exudative turkey meat characteristics, Poult. Sci., 77, 169, 1998.
13. Wang, L.-J., Byrem, T. M., Zarosley, J., Booren, A. M., and Strasburg, G. M., Skeletal muscle cal- cium channel ryanodine binding activity in genetically unimproved and commercial turkey populations, Poult. Sci., 78, 792, 1999.
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15. Boulianne, M. and King, A. J., Biochemical and color characteristics of skinless boneless pale chicken breast, Poult. Sci., 74, 1693, 1995.
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Selected bibliography
Egg and Poultry-Meat Processing, Stadelman, W. J, Olson, V. M., Shemwell, G. A., and Pasch, S., Ellis Horwood Ltd., Chichester, England, 1988.
Poultry Products Technology, 3rd ed., Mountney, G. J. and Parkhurst, C. R., The Haworth Press, Binghamton, New York, 1995.
Meat Science, 5th ed., Lawrie, R. A., Pergamon Press, Elmsford, New York, 1991.
Muscle Foods: Meat, Poultry, and Seafood Technology, Kinsman, D. M., Kotula, A. W., and Breidenstein, B. C., Eds., Chapman & Hall, New York, 1994.
Poultry Meat Science, Poultry Science Symposium Series, Vol. 25, Richardson, R. I. and Mead, G. C., Eds., CABI Publishing, Oxon, U.K., 1999.