Document 44Xn0Y9eNKqN9RBjbw734QJ1a

458 CHAPTER 42 } 962 Guide And Data Book Storage at 0 F or below resulted in minimum changes, even after nine months. In the results of palslability studies, it was found that storage poultry was less juicy than fresh control poultry. This condition was less serious when poultry was held at --10 F than when held at 10 F. Swanson and Sloan studied11 chemical changes in the proteins of ready-to-cook fowl held at --5 F over a period of 40 weeks. Proteolysis was indicated during frozen storage by increases in soluble nitrogen and non-protein nitrogen of both leg and breast muscle. The effect of variations in storage temperature on the quality of frozen turkeys was studied by Klose et al* for moisture losses, chemical changes, and palatability. Mature turkeys were subjected to semi-ecalding nnri sub-scalding, three packaging materials, and storage temperatures of --30 F, --10 F, 0 F, 10 F and a fluctuating temperature condition between --10 F and 10.F. Evaluations alter 6, 12 and 18 months storage indicated that, under average commercial conditions of frozen storage (moisture-impermeable package and temperature range of --10 F to 10 F), the only factor for which a periodic temperature fluctuation is inferior to the mean temperature is the accumulation of frost in the package. Frost formation, which influences appearance but not eating quality, increased with storage temperature, and for the --10 F to 10 F fluctuation was considerably greater than for the highest (10 F) constant temperature. Turkeys scalded at 140 F developed almost twice as much frost as those scalded at 126 F. Results after 12 months storage indicated a definite superiority of --10 F storage over 10 F and 0 F but no detect able organoleptic superiority of --30 F over --10 F. During recent years, the results of many studies have been reported dealing with the development of rancidity in poultry. The influence of dietary factors, handling prior to freezing, storage temperature, and length of storage period have been given special attention. Poultry fat will become rancid during very long storage periods or if the storage temperatures are exceedingly high. Cook and White studied*7-11 the development of rancidity in poultry fat and found that rancidity of an order that may af fect quality could be obtained by holding birds five to six weeks at 32 F, followed by a 27 week storage period at 10 F or by holding poultry for 87 weeks at 10--5 F. Wagoner, Vail, and Conrad reported1* that holding dressed poultry at cooler temperatures for one day or longer before eviscerating and freezing decreased the stability of the poultry during storage. Stability of poultry fat depends on its composition which in turn depends on the composition of the fat in the feed to a considerable extent. However, since most poultry feeds have about the same overall types and amount of fat, most fresh poultry fats will exhibit the same general range of composition and stability. Relative stability is conditioned primarily by two factors: content of unsaturated fatty acids and content of tocopherols. For turkeys, the presence in the feed of as little as 2 percent of a relatively unsaturated fat or oil will lead to an appreciably less stable carcass in frozen storage.*0 *1 Turkeys are recognized to be less stable than chickens. However, this difference in most cases is not due primarily to differences in content of unsaturated fatty acids. Mecchi et al demonstrateda a that the fatty acid composition of turkeys and chickens fed the same diet is essentially the same, and that the inherently greater stability of chicken fat compared to turkey fat is due to the greater level of tocopherol deposition effected by the chicken. From these studies and the report*4 of Criddle and Morgan, it is clear that the stability of poultry fat, which involves prevention of oxidative rancidity, can be increased considera bly with dietary supplements of the naturally occurring &0^. oxidants, tocopherols. This is neither necessary nor economic under normal eristing methods of storage. Stabilization of the highly susceptible fat in the surface layers of frozen eviscer ated poultry can also be accomplished by the application of synthetic antioxidants of acceptable food grade.*1-* Rancidity in frozen, whole, eviscerated poultry stored for as long as 12 months is, however, not a serious problem provided the bird is packaged is essentially impermeable film and held at 0 F or below. Danger of rancidification is greatly increased when poultry is cut up before freezing and storage, because of the increased surface exposed to atmospheric oxygen. Quality losses in frozen, packaged, cut-up frying were studied17 by Klose et al over temperatures of --30 F to 20 F and storage periods from 1 month to 2 years. Compari sons were made between --30 F controls and experimental temperatures for appearance, moisture loss, peroxide devel opment in the skin fat, off odors in the thawed raw meat, and off flavors in tire cooked meat. All commercial-type samples examined were acceptable after a storage period at 0 F of at least 6 months, and some were stable for more than a year. Within reasonable storage times, a series of temperature fluc tuations had the same deteriorative effect as a steady temper ature equal to the mean of the fluctuations. In a comparison of a superior (moisture-vapor proof) commercial type package with a fair commercial package, increased adequacy of pack aging resulted in as much extension in storage life as a decrease in storage temperature of about 20 F. The results indicate that no statement on storage life can have general value unless the packaging condition is accurately specified. Frozen storage tests** by Klose et al on commercial packs of ready-to-cook ducklings and ready-to-cook geese, over a 19month period and with steady storage temperatures covering the range from --30 to 20 F, established that these products have frozen storage lives comparable to other commercial forms of poultry. Ducks and geese should be stored at 0 For below in order to maintain their original high quality for 8 to 12 months. Storage studies** by Hanson et al on commercial and ex perimental packs of frozen fried chicken have indicated that the precooking produces a product much less stable than a raw product stored under the same conditions of temperature and package atmosphere. Rancidity development is the limiting factor and, surprisingly enough, it is detected in the meat slightly sooner than in the skin and fatty coating of the fried product. The marked beneficial effect of oxygen (air) free packaging was demonstrated in tests in which detectable off flavors were observed at 0 F in air packed samples after 2 months while nitrogen {tacked samples developed do off flavors for periods exceeding 12 months. The susceptibility of frozen fried chicken to storage deterioration indicates the Deed for low temperatures (0 F or --10 F) and short storage times (6 months or less) unless it is packed in an oxygen free at mosphere. In contrast to a loosely packed product, such as the frozen fried chicken mentioned above, Hanson and Fletcher have reported** that a solid-pack product such as chicken sod turkey pot pies, in which the cooked poultry is surrounded by sauce or gravy with consequent exclusion of air, had a storage life at 0 F of at least one year. As is the case with raw poultryt turkey products have less fat stability than do chicken prod ucts, but the stability can be increased by substitution of more stable fats in the sauces or by use of antioxidants. A quality defect found in precooked frozen products containing [yozen Poultry Products uce or gravy is a liquid separation and curdled appearance of the sauoe or gravy when thawed for use. This separation is ^^ejoely sensitive to storage temperature. Sauces can be stored at least 5 times as long at 0 F as at 10 F before separa- ^oa tskp* place- Hanson et al established41 that the flour in the sauce was the cause of the separation, and found among s large number of alternative thickening agents that waxy nee flour produced superior stability. Sauces and gravies pre- pued with waxy rice flour are completely stable for approxi- ^telyoyearatOF. ' gince precooked frozen foods are not apt to be sterilized in the reheating process in the home, there is an added responsi bility for the processor to keep bacterial counts in the product veil below hazardous levels. Extra precautions should be taken in general plant sanitation, in rapid chilling and freez- jjjg 0f the cooked products, and in care that the products do oot reach a temperature at any time during storage or distri bution that will permit bacterial growth THAWING AND UTILIZATION Under ordinary conditions, it is desirable to keep the poultry frozen until shortly before it is to be consumed. The general procedure is to defrost in air or in water. Hoffert et al found*- no significant differences in palatability between thawing in oven, refrigerator, room and water. For turkeys that have been scalded at high temperatures and fast frozen to give a light appearance, it is especially important to keep the temperature in retail storage and dis play as low as possible (0 F is a reasonable goal) to prevent darkening. Darkening on thawing will be minimized by thaw ing in the package. It has become common practice in some retail stores to allow frozen poultry to start thawing in the chilled (33-38 F) section of the meat display case for sale on that particular day This is an advantage to the consumer who wants to cook the poultry that night. However, this is a safe practice only if care ful, constant control is maintained over the chilled inventory so that the product is not held beyond its overall shelf life in store and home. See Chapter 32 for a detailed discussion of shelf life of chilled poultry. There has been some marketing of ready-to-cook turkeys in the form of a frozen, prestuffed, raw product. Extreme care should be exercised in the production and consumption of this type of product, in order to insure that the original bacterial count in the birds fmri stuffing is at a minimum, and that in roasting the internal temperature reaches a value sufficiently high to provide a safe product. REFERENCES 1 C. H. Koonx, M. I. Darrow, and E. O. Eesary: Factors influ encing tenderness of principal muscles composing the poultry rarcass (Food Technology, February 1954, p. 97). * B- Lowe: Effect of drawing before freezing on the palatability "Poultry (Proceedings of 7th World1! Poultry Congress, 1939, p. . * G. F. Stewart, B. Lowe, and M. Morr: Post-mortem changes f Ne* York dressed poultry at 35 F (UE. Egg and Poultry Magazine, September 1941, p. 542). L. Hanson, G. F. Stewart, and B. Lowe: Palatability and histological changes occurring in New York dressed broilers held at 1-7 C (35 F) (Food Research, March-April 1942, p. 148). L. Graf and G. F. Stewart: Slack va. sub-ecald for broilers {Poultry Processing and Marketing, June 1953, p. 12). * W. G. Shannon. W. W. Marion, and W. J. Stadelman: Effect 01 temperature and time of scalding on the tenderness of breast aett of chicken (Food Technology, May 1957, p. 284). 459 7 A. A. Klose et al: Poultry tenderness. I. Influence of process ing on tenderness of turkeys (Food Technology, January 1959a, P- 20). * M. F. Pool et al: Poultry tenderness. II. Influence of process ing on tenderness of chickens (Food Technology, January 1959, p. 25). * Encyclopedia Issue (Modem Packaging, November 1959, Packaging Catalog Corp., Bristol, Conn., 1960). u C. H. Koonx and J. M. Ramsbottom: A method for studying the histological structure of frozen products. I. Poultry (rood Research, March-April 1939, p. 117). u C. W. DuBois, D. K. Tressler, and F. Fenton: The effect of the rate of freezing and temperature of storage on the quality of frozen poultry (Refrigerating Engineering, August 1942, p. 93). a L. van den Berg and C. P. Lentz: Factors affecting freezing rate and appearance of eviscerated poultry frozen in air (Food Technology, April 1958, p. 183). * A. A. Klose and M. F. Pool: Effect of freezing conditions on appearance of frozen turkeys (Food Technology, January 1956, p. 34). u E. Simons: Jet-freezing newest quick-freeze system (Food Engineering, November 1953, p. 57). u W. B. et al: Brine immersion cooling and freezing of packaged ready-to-cook poultry (Refrigerating Engineering, July 1954, p. 61). u C, P. Lentz and L. van den Berg: Liquid immersion freezing of poultry (Food Technology, April 1957, p. 247). 17 L. van den Berg and C. P. Lents: Factors affecting freezing rates of poultry immersed in liquid (Food Technology, July 1957, p. 377). ** I. J. Pffug: Immersion freezing found to improve poultry appearance (Frosted Food Field, June 1957, p. 17). 11 C. H. Koonx and J. M. Ramsbottom: Influence of freezing on color of bones and adjacent tissues (Food Research, SeptemberOetober 1947, p. 393). ** A. W. Brant and Q. F. Stewart: Bone darkening in frozen poultry (Food Technology, May 1950, p. 168). C. Ellis and J. G. Woodroof: Prevention of darkening in frozen broilers (Food Technology, September 1959, p. 533). B C. H. Koons, R. D. Trelease, and H. E. Robinson: Low storage temperatures keep dressed poultry good longer (U. S. Egg and Poultry Magazine, December 1947, p. 12). ** R. Wills et al: Frozen storage of poultry, influence of eviscer ation practice, packaging and storage temperature (Refriger ating Engineering, July 1948, p. 49). M R. Wills, B. Lowe, and G. F. Stewart: Poultry storage at subfreezing temperatures--comparisons at --10 and +10 F (Refrigerating Engineering, September 1948, p. 237). 0 M. H. Swanson, and H. J. Sloan: Some protein changes in stored frozen poultry (Poultry Science, July 1953, p. 643). * A. A. Klose, M. F. Pool, and H. lineweaver: Effect of fluctuating temperatures on frozen turkeys (Food Technology, August 1955, p. 372). 17 W. H. Cook and W. H. White: Frozen storage of poultry IV. Further observations on surface drying- and peroxide oxygen formation (Canadian Journal of Research, October 1940, p- 363). ** W. H. Cook and W. H. White: Frozen storage of poultry m. Peroxide oxygen and free fatty acid formation (Food Research, September-October 1939, p. 433). ** C. E. Wagoner. G. E. Vail, and R. M. Conrad: The influence of preliminary holding conditions on deterioration of frozen poultry (Poultry Science, March 1947, p. 170). * A. A. Klose et al: Chemical characteristics of turkey carcass fat as a function of dietary fat (Poultry Science, March 1952a, p.354) . 0 A. A. Klose et al: Quality and stability of turkeys as a func tion of dietary fat (Poultry Science, January 1953, p. 82). a E. P. MecchL et ai: The role of tocopherol content in the comparative stability of chicken and turkey fat (Poultry Science, November 1956, p. 1238). . ** E. P. Mecchi, et al: Further studies on tocopherol content and stability of carcass fat of chickens and turkeys (Poultry Science, November 1956, p. 1246).