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434 CHAPTER 39 (100-fold) essence, is used for manufacturing, primarily for jellies. Availability of seven-fokl frozen concentrate provides a more economical way of marketing high-quality strawberry juice solids. Concentrates of red raspberry, black raspberry, and blackberry juices are also available in limited quantities. The process for preparation of strawberry and other berry juice concentrates involves essence-recovery in which 12-20 percent of the juice is separated by a stripping procem using a steam injection heater. Vapors containing volatile flavors are concentrated in a fractionating column to the desired degree. The juice remaining from the essence-recovery step is concen trated under vacuum 3- to 7-fold by volume. A maximum temperature of 100 F for 2>$ hr should not be exceeded for strawberry, whereas temperatures up to 130 F may be used in preparing boysenberry concentrate in a batch-type operation; Preparation of juice for. concentration involves chop ping or coarae milling of cold, sound berries and mixing with pectic enzymes and filter aid. After several hours (4-5 at room temperature), juice is expressed with a bag press or rack and cloth press. The cloudy juice is clarified in a filter press. Recovered essences have been concentrated and packaged separately so that the jelly manufacturer can incorporate the essence in the jelly just before filling. This procedure reduces greatly the amount of essence lost by volatilization. The essence can also be incorporated in the concentrate to make a full-flavored product, for shipping as a single unit. Concentrated juice, without essence, can be packed in an enamel-lined container which need only be liquid tight. Concentrated essence should be kept in a carefully sealed can to avoid losses of the highly volatile flavor. Both juice concen trate and essence are kept frozen for proper quality retention. BIBLIOGRAPHY C. D. Atkins and A. H. Rouse: Time-temperature relation ships for heat inactivation of pectinesterase in citrus juices (Food Technology, VoL 7, 1953, p. 489). C. D. Atkins ct oi; Gelation and clarification in concentrated citrus juices. Iff. Effect of heat treatment of Valencia orange and Duncan grapefruit juices prior to concentration (Food Technology, Vol. 7, 1953, p. 62). O. W. Bissett cl al: Stability of frozen concentrated orange juice. III. Effect of heat treatment in the production of higb-Bnx frozen concentrates (Food Technology, Vol. 11, 1957, p. 96). A. H. Brown ct al: Rapid heat processing of fluid foods by steam injection {Industrial and Engineering Chemistry, VoL 43, 1951, p. 2949). W, V. Cniess and A. Gibson: Preparation of frozen pack apple juice concentrate {Frosted Food Field, Vol. 9, 1949, p. 8). C. W. DuBois and T. J. Kew: Storage temperature effects on frozen citrus concentrates (Rectigb&4tino Engineering, August 1951, p. 772). N. H. Eisenhardt ct al: The Preparation of Full-flavor Berry Juice Concentrates (U. S. Department of Agriculture, ARS 73-20, September 1958). - R. K. Eekew ct al: Frozen concentrated apple juice (Industrial and Engineering Chemistry, Vol. 43, 1951, p. 2397). R. K. Eskew ct al: Preparation of Pud-Flavor Frozen Grape Juice Concentrates (USDA, Bureau of Agricultural and Indus trial Chemistry, Eastern Utilization Research Laboratory, Mimeo. AIO301, March 1951). R. K. Eskew ct al: High Density Full-Flavor Grape Juice Con centrate (USDA, Bureau of Agricultural and Industrial Chemis- 1962 Guide And Data Book try, Eastern Utilization Research Laboratory, Minw, Arr, 342, September 1952). ' H. C. Gore: Apple Sirup and Concentrated Cider (USDA V,, book, 1914, p.227). ^ N. V. Hayes, R. H. Cotton, and W. R. Roy: Problems b d*. hydrating orange juice (Food Packer, October 1946). ^ R. W. Holley, B. Stoyla, and A. D. Holley: The identification of some volatile constituents of Concord grape juice (Foal o search, 20, 328, 1955). ^ M. B. Jacobs (ed.): The Chemistry and Technology of Food anA Food Products (lnterscience Publishers, Inc., New York, iq&i Vol. 2 and 3,2nd ed.). ' V. P. Kaufman, C. C. Nimmo, and L. H. Walker: Frozen Apple Juice Concentrate: Application of Laboratory Data to Pro*. poetise Commercial Operations (U. S. Bureau of Agricultural and Industrial Chemistry. AIC, 1950, p. 293). E. L. Moore ct al: Storage changes in frozen concentrated citrus juices (Preliminary Report, Proceedings, Florida State Horticut tural Society, 63rd Annual Meeting, 1950). J. G. Moore: Full flavor concentrates by new essence-recoverr technique (Food Engineering, January 1954). A. F. Mureh and J. V. Ziemba: Concentrating advances bring superior flavors (Food Engineering, December 1957). ^ C. C. Nimmo el al; Influence of storage conditions in frozen and canned apple juice concentrates (Food Technology, Vol. 6, 1052. p. 31). * T. R. Olive: Freeze-Concentration process employs new ap proach (Food Industry, VoL 20, 1948, p. 1432). R. W. Olsen ei al: Gelation and clarification in concentrated citrus juices, II effect of quantity of pulp in concentrate from seedy varieties of fruit (Food Technology, Vol. 5, 1951, p 530). J. D. Pouting et al: Making berry juices and concentrates lot use in preserves, juices, syrups (ConnerfPacker, VoL 128, Sep tember 1959, p. 19). J. D. Pouting et al; Continuous jelly manufacture (Food Tech nology, VoL 12,1958, p- 252). N. F. Roger: The recovery of methyl anthranilate in Concord grape essence (Food Technology, 15,1961, p. 309). A. H. Rouse and C. D. Atkins: Further results from a study of heat inactivation of pectinesterase in citrus juices (Food Technol ogy, VoL 7, 1953, p.221). A. H. Rouse and C. D. Atkins: Heat inactivation of pectinea- terase in citrus juices (Food Technology, Vol. 6, 1952, p. 291). H. C. Schwarz and F. E. Penn: Production of orange juice concentrate and powder (Industrial and Engineering Chemistry, Vol. 40, 1948, p.938). Superior dehydrated juices from continuous vacuum process (Food Engineering, VoL 27, March 1955, p. 71). D. K. Tressler et al: Fruit and Vegetable Juices (The Avi Pub lishing Co., Inc., New York, 1939, p. 202). U. S. Standards for Grades of Frozen Concentrated Orange Juice (7 CFR, Section 52, 492; USDA Production and Mar keting Administration, Washington 25, D. C.). U. S. Standards for Grades of Frozen Concentrated Sweetened Grape Juice (USDA, Production and Marketing Administration, Washington 25, D. C., November 1957). L. H. Walker et al: Preparation of frozen apple juice concen trate (Food Technology, Vol. 5, 1951, p. 148). L. H. Walker et al: Concentration of strawberry juice (Food Technology, VoL 8,1953, p. 350). L. H. Walker et al.: Frozen apple juice concentrate: permissible temperatures for concentration of western varieties of appk* (Food Technology, Vol. 8, 1954, p. 108). F. W. Wenzel et al: Gelation and classification of concentrated citrus juices, I introduction and present status (Food Technology, Vol. 5, 1951, p. 454). C. E. Wright: Now--orange concentrate with 95% -flavor esters (Golden Gift, Inc.) (Food Engineering, Vol. 27, No. 2, 1955, p. 70). CHAPTER 40 FROZEN FISHERY PRODUCTS pigging Considerations for Freezing and Storage; Types of Packages,- Freezing Methods; Calculation of Refrigeration ggquirements; Storage of Frozen Fish; Effect of Composition, Temperature, Humidity, Packaging, and Glazing on Quality,- Space Requirements for Frozen Fish; Transportation and Marketing THE kinds of frozen fishery products vary with geographi freezing costs, lower handling costs, and lower packaging ma es! location, and consist primarily of groundfish fillets, terial costs. Tests conducted by the Bureau of Commercial ggaUops, breaded precooked fish sticks, and bait and animal Fisheries Technological Laboratories demonstrated these bod in the northeastern states; of round or dressed halibut findings conclusively. lod salmon, halibut and salmon steaks, groundfish fillets, and These same tests also indicated that the time required to but and animal food'in the northwestern states; of halibut freeze packaged fish fillets in a plate freezer is directly propor ind ralmon in Alaska; of shrimp, oysters, crabs and other tional to the square of the package thickness. Thus, if it takes gjy.HfiA and Crustacea in the. Gulf of Mexico and south 180 min to freeze packaged fish fillets 2 in. thick, it will take Atlantic states; and of round or dressed fish in the states about 281 Twin to freeze packaged fish fillets 2J/ in. thick. The bordering on the Great Lakes. insulating effect of the packaging material, the fit of the The fishery products obtained from these areas differ con product in the package and the total surface area of the pack siderably in both physical and chemical composition. Some age must be considered. A packaging material with a low fid) such as haddock or cod, for example, are readily adaptable moisture vapor permeability has an insulating effect which to freezing and have a comparatively long storage life, while increases freezing time and costs. The rate of heat transfer other species such as salmon tend to become rancid during through the packaging material is inversely proportioned to frozen storage and therefore have a relatively short storage its thickness; therefore, a packaging material should be used life. The differences in the composition of the many species of which is thin enough to produce rapid freezing, produce an fish and the differences in marketing requirements necessitate adequate moisture vapor barrier in frozen storage, and thick consideration of the specific individual product with regard to enough to withstand heavy abuse. Aluminum foil cartons and quality maintenance and methods of packaging, freezing, cold packages offer an advantage in this regard. Proper fit of pack storage, and handling. age to product is essential, otherwise the insulating effect of At temperatures below freezing, bacterial activity as a cause the air space formed will reduce the freezing rate of the of spoilage is somewhat limited..However, certain chemical product and increase freezing costa. The surface area of the and physical changes do occur which may eventually cause package is also important because of its relation to the size deterioration of the product. The magnitude of these changes of the freezer shelves or plates. Maximum utilization of freezer and their effect on product quality depends upon the initial space can be obtained by designing the package so that it fits qualityof the fish being frozen, the composi tion of the fish, the the freezer properly. freezing method, and the frozen storage environment or com bination thereof. These considerations are reflected in the four Package Considerations for Frozen Storage principal phases of frozen fish production and handling; Fishery products will lose considerable moisture and namely, packaging, freezing, cold storage and transportation, become tough and fibrous during frozen storage unless a described in chapter. package having a low moisture vapor permeability is used. PACKAGING Also, the package in contact with the product must be resist ant to oils or moisture exuded from the product, otherwise Packaging materials used for frozen fish are similar to those rancidity of the oils and softening of the package material used for other frozen foods. In selecting a package three fac will occur. The package must fit the product tightly in order to tors should be considered: (1) the effect of unit package size on minimize air spaces and thereby reduce moisture migration the freezing and handling requirements; (2) the protection from product to the inside surfaces of the package. afforded the product by the package; and (3) the attractiveneaaod consumer appeal of the package. Types of Packages Proper consideration of these factors should result in a Packaging materials in general use for fishery products con Package which will provide rapid, efficient freezing, ease of handling, adequate storage life, and product sales appeal. sist of paper board cartons coated with various waterproofing materials or laminated with moisture-vapor resistant films and Package Considerations in Freezing heat sealable overwrapping materials having a low moisturevapor permeability. Paper board cartons are usually made of Sufficient study is not always given to the type and size of a bleached paper board stock, which is coated with a suitable' P&ckage. Refrigeration equipment and packaging materials macrocrystalline wax, polyethylene or other plastic material, we frequently purchased without considering the effect of the or laminated with aluminum foil or other moisture-vapor package size on the freezing rate and efficiency. For example, resistant film. Microcryst&lline wax coated paper board car a thin consumer package will result in a faster rate of product tons are used for most fishery products. In some cases paper freezing, lower total freezing costs, higher handling costs and board cartons laminated with aluminum foil are used for "W** packaging material costs; a thicker institutional type specialty items where the added protection afforded and the package will result in a slower rate of product freezing, higher consumer appeal warrants the extra cost. Waxed paper board 435 j : IJ :r? v< :i