/ NOAA TR NMFS SSRF-650 A UNITED STATES DEPARTMENT OF COMMERCE PUBLICATION ►, .^o^., NOAA Technical Report NMFS SSRF-650 U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Marine Fisheries Service Effects of Some Antioxidants and EDTA on the Development of Rancidity in Spanish Mackerel {Scomberomorus maculatus) During Frozen Storage ROBERT N. FARRAGUT SEAHLE, WA February 1972 LIBRARY Woods H. NOAA TECHNICAL REPORTS National Marine Fisheries Service, Special Scientific Report-Fisheries Series The major responsibilities of the National Marine Fisheries Service (NMFS) are to monitor and assess the abundance and geographic distribution of fishery resources, to understand and predict fluctuations in the quantity and distribution of these resources, and to establish levels for optimum use of the resources. NMFS is also charged with the development and implementation of policies for managing national fishing grounds, develop- ment and enforcement of domestic fisheries regulations, surveillance of foreign fishing off United States coastal waters, and the development and enforcement of international fishery agreements and policies. NMFS also as- sists the fishing industry through marketing service and economic analysis programs, and mortgage insurance and vessel construction subsidies. It collects, analyzes, and publishes statistics on various phases of the industry. The Special Scientific Report — Fisheries series was established in 1949. The series carries reports on scien- tific investigations that docmnent long-term continuing programs of NMFS, or intensive scientific reports on studies of restricted scope. The reports may deal with applied fishery problems. The series is also used as a medium for the publication of bibliographies of a specialized scientific nature. NOAA Technical Reports NMFS SSRF are available free in limited numbers to governmental agencies, both Federal and State. They are also available in exchange for other scientific and technical publications in the marine sciences. Individual copies may be obtained (unless otherwise noted) from NOAA Publications Section, Rockville, Md. 20852. Recent SSRF's are: 604. The flora and fauna of a basin in central Florida Bay. By J. Harold Hudson, Donald M. Allen, and T. J. Costello. May 1970, iii + 14 pp., 2 figs., 1 table. 605. Contributions to the life histories of several penaeid shrimps (Penaeidae) along the south Atlantic Coast of the United States. By William W. Anderson. May 1970, iii + 24 pp., 15 figs., 12 tables. 606. Annotated references on the Pacific saury, Colol- abis saira. By Steven E. Hughes. June 1970, iii + 12 pp. 607. Studies on continuous transmission frequency modulated sonar. Edited by Frank J. Hester. June 1970, iii + 26 pp. 1st paper, Sonar target classification experiments with a continuous- transmission Doppler sonar, by Frank J. Hester, pp. 1-20, 14 figs., 4 tables; 2d paper. Acoustic target strength of several species of fish, by H. W. Volberg, pp. 21-26, 10 figs. 608. Preliminary designs of traveling screens to col- lect juvenile fish. July 1970, v + 15 pp. 1st paper. Traveling screens for collection of juvenile salmon (models I and II), by Daniel W. Bates and John G. Vanderwalker, pp. 1-5, 6 figs., 1 table; 2d paper. Design and operation of a canti- levered traveling fish screen (model V), by Dan- iel W. Bates, Ernest W. Murphey, and Earl F. Prentice, 10 figs., 1 table. 609. Annotated bibliography of zooplankton sampling devices. By Jack W. Jossi. July 1970, iii + 90 pp. 610. Limnological study of lower Colombia River, 1967-68. By Shirley M. Clark and George R. Snyder. July 1970, iii + 14 pp., 15 figs., 11 tables. 611. Laboratory tests of an electrical barrier for con- trolling predation by northern squawfish. By Galen H. Maxfield, Robert H. Lander, and Charles D. Volz. July 1970, iii + 8 pp., 4 figs., 5 tables. 612. The Trade Wind Zone Oceanography Pilot Study. Part VIII: Sea-level meteorological properties and heat exchange processes, July 196.3 to June 1965. By Gunter R. Seckel. June 1970, iv -|- 129 pp., 6 figs., 8 tables. 618. Sea-bottom photographs and macrobenthos col- lections from the Continental Shelf off Massa- chusetts. By Roland L. Wigley and Roger B. Theroux. August 1970, iii + 12 pp., 8 figs., 2 tables. 614. A sled-mounted suction sampler for benthic or- ganisms. By Donald ?il. Allen and J. Harold Hudson. August 1970, iii + 5 pp., 5 figs., 1 table. 615. Distribution of fishing effort and catches of skip- jack tuna, Katsuwonus pelamis, in Hawaiian waters, by quarters of the year, 1948-65. By Richard N. Uchida. June 1970, iv -f 37 pp., 6 figs., 22 tables. 616. Effect of quality of the spawning bed on growth and development of pink salmon embryos and alevins. By Ralph A. Wells and William J. Mc- Neil. August 1970, iii -f- 6 pp., 4 tables. 617. Fur seal investigations, 1968. By NMFS, Ma- rine Mammal Biological Laboratory. December 1970, iii 4-69 pp., 68 tables. 618. Spawning areas and abundance of steelhead trout and coho, sockeye, and chum salmon in the Columbia River Basin - past and present. By Leonard A. Fulton. December 1970, iii -|- 37 pp., 6 figs., 11 maps, 9 tables. 619. Macrozooplankton and small nekton in the coastal waters off Vancouver Island (Canada) and Washington, spring and fall of 1963. By Donald S. Day, January 1971, iii + 94 pp., 19 figs., 13 tables. 620. The Trade Wind Zone Oceanography Pilot Study. Part IX: The sea-level wind field and wind stress values, July 1963 to June 1965. By Gunter R. Seckel. June 1970, iii -|- 66 pp., 5 figs. Continued on inside back cover. .^0 MMOsp, ^'^em of U.S. DEPARTMENT OF COMMERCE Maurice H. Stans, Secretary NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION Robert M. White, Administrator NATIONAL MARINE FISHERIES SERVICE Philip M. Roedel, Director NOAA Technical Report NMFS SSRF-650 Effects of Some Antioxidants and EDTA on the Development of Rancidity in Spanish Mackerel (Scomberomorus maculatus) During Frozen Storage ROBERT N. FARRAGUT Marine Biologic:-! L-boritory LIBRARY SEP 1 3 1972 Woods Hole, IV;ass. SEAHLE, WA February 1972 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C., 20402 - Price 25 cents Stock Number 0320-0032 The National Marine Fisheries Service (NMFS) does not approve, rec- ommend or endorse any proprietary product or proprietary material mentioned in this publication. No reference shall be made to NMFS, or to this publication furnished by NMFS, in any advertising or sales pro- motion which would indicate or imply that NMFS approves, recommends or endorses any proprietary product or proprietary material mentioned herein, or which has as its purpose an intent to cause directly or indirectly the advertised product to be used or purchased because of this NMFS publication. CONTENTS Page Introduction 1 Part I. The effect of various treatments upon the development of rancidity in Spanish mackerel 2 Materials and procedure 2 Results 2 Discussion 7 Part II. The effect of various EDTA compounds upon texture and the development of rancidity in Spanish mackerel fillets 9 Materials and procedure 9 Results 9 Discussion 12 Literature cited 12 Figures No. 1. Organoleptic score for flavor of Spanish mackerel fillets 4 2. Organoleptic score for texture of Spanish mackerel fillets 5 3. Peroxide content of the oil fraction from Spanish mackerel 5 4. Free fatty acid content of oil fraction from Spanish mackerel fillets . 7 5. Free fatty acid content of oil from Spanish mackerel fillets treated with 180 ppm of EDTA and certain salts of EDTA 9 6. Organoleptic score for texture of Spanish mackerel fillets treated with 180 ppm of EDTA and certain salts of EDTA 10 No. TabI es 1. Organoleptic scores of Spanish mackerel {Scomberomonis maculaUis) fillets packed in vacuum-sealed bags 3 2. Organoleptic scores of glazed Spanish mackerel {Scomber- omorus tnaculahis) fillets 3 8. Organoleptic scores of glazed whole heads-off Spanish mackerel {Scomberomonis macuIaUis) 4 4. Peroxide content of Spanish mackerel (Scomberomonis macu- lat-iis) packed in vacuum-sealed bags 5 5. Peroxide content of glazed Spanish mackerel (Scomberomonis maculatus) fillets 6 6. Peroxide content of glazed whole heads-off Spanish mackerel (Scomberomorus viacnlahis) 6 7. Free fatty acid content of Spanish mackerel (Scomberomorus maculatus) fillets packed in vacuum-sealed bags 7 8. Free fatty acid content of Spanish mackerel (Scomberomorus maculatus) glazed fillets 8 ill CONTENTS--Cont. Tables-Cont. 9. Free fatty acid content of glazed whole heads-off Spanish mack- erel (Scomberomorus maculaUis) 8 10. Fatty acid content of Spanish mackerel {Scomheromorus mac- ulatus) packed in vacuum-sealed bags 10 11. Peroxide content of Spanish mackerel {Scomberomorus niac- ulatus) packed in vacuum-sealed bags 11 12. Texture scores of Spanish mackerel {Scomberomorus macu- laUis) packed in vacuum-sealed bags 11 IV Effects of Some Antioxidants and EDTA on the Development of Rancidity in Spanish Mackerel (Scomeromorus maculafus) During Frozen Storage by ROBERT N. FARRAGUT, Chemist' National Marine Fisheries Service Fishery Products Laboratory Pascagoula, Mississippi 39567 ABSTRACT Spanish mackerel {Scomheromoriis maciilatus) were treated with antioxidant so- lutions containing BHA and BHT (Tenox 4); BHA, BHT, PG, citric acid, and pro- pylene glycol (Tenox6); Tenox 4 plus EDTA; Tenox 6 plus EDTA; Ca(Na)2EDTA; (Na)2EDTA; (CA)2EDTA; and (Na)4EDTA both by dipping and injecting methods. Samples analyzed at 3-month intervals showed fillets packed in vacuum and treated with EDTA remained in good condition over the 12-month storage period. However, samples treated with (Na)4EDTA remained superior to other samples throughout the storage period. INTRODUCTION Spanish mackerel can be found in abundance in waters from the Chesapeake Bay to Texas. Early records indicate major landings of Span- ish mackerel from the Chesapeake Bay during the last part of the 19th century. Around the turn of the century, landings declined in the Chesapeake Bay area but increased in southern Florida waters, where the fishery stabilized and is presently located. The stocks are tremendous but annual landings have remained in the neighborhood of 8 million pounds for the past 18 years (Lyies, 1969). At present the commercial processing of Spanish mackerel usually is limited to eviscer- ation and freezing of whole fish. The fish are usually marketed in this manner with only a small percentage of the catch sold as boneless fillets or steaks. Mackerel treated in this man- ner begin to show signs of rancidity within as ' Presently National Marine Fisheries Service, Southeast Fisheries Center Miami Laboratory, Miami, Fla. 33149. little time as a 3-month period and ai'e usually rejected by taste panels between the sixth and ninth month of storage. As good fish, Spanish mackerel have many assets. The delicate flavor, the good yield of edible boneless fillets, and their availability con- tribute to the demand for good quality Spanish mackerel. A major factor influencing in- creased production and wider markets is the rapid onset of rancidity that occurs prior to and during frozen storage. The problem of rancidity in fish has been studied for many years. Reports of the eflfect of various antioxidants on the development of i-ancidity in red spring salmon, haddock fillets, herring, and other species show little or no in- crease in shelf life over the controls. Typical antioxidants used in these experiments included BHT (butylatedhydroxytoluene),BHA (buty- lated hydroxyanisole) , propylene glycol (Voss and Munkmer, 1966), ethyl gallate, ascorbic acid, and a-tocopherol (vitamin E). Castell and Spears (1968) report the induction of ran- cidity by minute quantities of trace minerals in fish tissue homogenates of non-oily species. The presence of trace metals such as iron and copper in oils is known to increase the rate of development of rancidity. If this were the case in whole fish, treatment by a chelating agent such as EDTA (ethylenediaminetetraacetic acid) should retard rancidity. The use of EDTA compounds for the preser- vation of haddock fillets was reported by Power et al. (1968). Power found that iced haddock fillets dipped in l','r tetrasodium EDTA will remain organoleptically acceptable 11 days longer than untreated controls. Tarr (1947) investigated the potential value of antibiotics for the preservation of fish. The reduction of bacteria by antibiotics did enhance the keeping qualities of certain species but did not significantly retard rancidity. This jmper will be divided into two parts, The first part will describe an experiment which was designed to show the eff"ect of some antioxi- dants and EDTA, as well as vacuum pack- aging, on the development of oxidative ran- cidity in frozen Spanish mackerel. The second part will describe the effects of various EDTA compounds on the development of rancidity in and on the texture of Spanish mackerel fil- lets. Part I. THE EFFECT OF VARIOUS TREATMENTS UPON THE DEVELOPMENT OF RANCIDITY IN SPANISH MACKEREL MATERIALS AND PROCEDURE A lot of Spanish mackerel was obtained from a Marathon, Fla., dealer and processed less than 24 hr from time of capture. Samples were either dipped or injected with the various so- lutions. Preliminary experiments revealed an uptake of 50 ppm of the antioxidants for every 1.1 g of oil when the fish were dipped. These calculations were used to determine a dipping time of 20 min. Fish were injected with anti- oxidant solutions with a Hamilton syringe and a 16-gauge needle. Samples were given four injections of 1 ml each to achieve the 250 ppm level. The injections were placed along the lateral line of each fish at 2- to 3-inch intervals. The samples were placed in the freezer within 1 hr after injecting. Antioxidants were obtained from Eastman Organic Chemical Co. as solutions. The solu- tions contained BHA and BHT (Tenox 4), BHA, BHT, PG, citric acid, and propylene gly- col (Tenox 6). EDTA was added to these so- lutions as well as being used independently. The treated fillet samples were packed in Cry- ovac bags and a vacuum of 29 inch Hg pulled on the bag with a Cryovac vacuum machine. The vacuum-sealed samples were frozen imme- diately. Other fillets were frozen and glazed for comparison. Whole fish were treated, froz- en, and glazed. All glazed samples were glazed twice to insure a heavy and complete covering of ice over the samples. All samples were stored at —10° F. Samples were analyzed in duplicate every 3 months for peroxide content, free fatty acid content, and organoleptic characteristics. Oil was extracted from the samples with acetone and then with 1:1 (by volume) petroleum ether and ethyl ether. The ether was flash-evapo- rated, and the extracted oil was analyzed for peroxide and free fatty acid content according to AOCS method (American Oil Chemists' So- ciety, 1964). Organoleptic evaluations were performed on broiled portions by an 8-member panel using a 5-point scale for appearance, tex- ture, and taste. The 5-point scale consisted of 5 points for excellent, 4 for very good, 3 for good, 2 for slightly good, 1 for borderline, and 0 for inedible. Appearance, texture, and taste were rated individually. Average scores of the 8-member taste panel are indicated in Tables 1, 2, and 3. RESULTS After 9 months' frozen storage, samples packed in vacuum received higher organoleptic scores than glazed fillets or glazed whole fish (Tables 1, 2, 3). Control samples packed in vacuum were rated 2.6, 2.3, and 2.5 as an aver- age of the taste-panel results in appearance, flavor, and texture, respectively, after 9 months' storage. These scores compared to 2.0, Table 1.- — Organoleptic scores of Spanish mackerel (Scomberomorus maculatus) fillets packed in vacuum-sealed bags. 2 weeks 2 months 3 months 6 months 9 months AFT AFT AFT AFT AFT Control Tenox 4: Injected Dipped . Tenox 6; Injected Dipped . EDTA: Injected Dipped . Tenox 4 + Injected Dipped . 3,8 4.0 3.8 3.6 4.0 3.8 EDTA: Tenox 6 + EDTA: Injected Dipped 4.0 4.2 4.2 4.0 4.5 4.0 4.2 4.4 4.5 4.6 3.8 3.4 3.0 2.8 3.4 2.6 2.3 2.5 3.6 3.6 3.8 3.8 3.8 4.4 4.0 4.2 2.8 3.0 3.6 1.3 2.0 1.3 4.2 4.0 3.6 3.6 4.0 3.8 3.8 3.6 3.2 2.6 3.0 1.0 2.3 1.8 4.0 4.2 3.2 3.6 3.8 3.8 3.8 4.4 3.2 2.6 3.0 1.1 2.3 1.8 4.0 4.0 4.0 4.2 4.2 4.4 4.2 4.6 2.2 3.2 3.6 2.1 2.3 2.0 4.0 4.0 4.0 3.4 4.0 3.8 3.4 3.8 3.2 3.2 3.2 3.0 3.3 3.0 4.6 4.4 4.4 4.2 4.0 4.2 4.0 4.6 2.8 3.2 3.6 3.0 3.3 3.2 4.2 4.2 4.0 3.4 3.6 3.8 3.8 4.4 2.4 2.2 3.6 2.7 3.0 2.5 3.8 3.8 4.0 4.2 4.2 4.2 3.6 4.0 3.8 2.8 3.6 2.7 2.3 2.7 3.8 4.0 4.2 4.2 4.2 4.2 3.4 3.8 3.8 3.0 3.4 2.2 1.7 2.5 4.0 4.0 4.2 4.0 4.2 4.4 3.2 3.8 2.8 3.2 3.4 2.0 1.3 2.0 A = Appearance F = Flavor T = Texture Table 2. — Organoleptic scores of glazed Spanish mackerel {Scomberomonis maculatus) fillets. 2 weeks 2 months 3 months 6 months 9 months AFT AFT AFT AFT AFT Control 4.2 3.6 4.2 4.2 4.4 4.8 4.4 3.8 4.4 3.2 2.8 2.8 2.0 2.0 2.3 Tenox 4: Injected 4.2 3.4 4.0 3.6 3.8 4.4 4.0 3.8 4.0 1.7 1.7 2.5 1.4 1.3 1.6 Dipped 4.6 4.2 4.4 4.0 4.4 4.6 4.2 4.0 4.2 2.6 2.6 3.2 0.8 0.0 0.0 Tenox 6: Injected 4.2 4.0 4.4 3.8 4.0 3.6 3.8 4.2 4.0 3.0 3.0 2.8 0.8 0.0 1.2 Dipped 4.2 3.6 4.0 3.6 3.2 3.2 4.0 3.0 3.2 1.2 1.5 2.2 1.1 0.0 1.0 EDTA: Injected ..4.4 4.4 4.4 4.0 4.2 3.6 4.0 4.2 3.6 3.4 3.4 4.0 3.0 2.7 3.0 Dipped 4.2 3.6 4.5 3.6 4.2 3.8 3.8 4.0 3.4 1.7 1.5 2.2 2.0 3.3 2.5 Tenox 4 + EDTA: Injected 4.2 3.8 4.0 4.2 3.0 3.8 4.0 3.8 3.6 2.0 3.0 3.0 2.5 3.0 1.5 Dipped 4.2 4.0 3.8 4.0 3.6 3.0 4.0 3.8 3.2 3.0 2.6 2.2 2.0 3.0 1.7 Tenox 6 + EDTA: Injected 4.2 4.2 4.4 4.0 3.8 3.6 4.0 3.8 4.2 3.4 3.2 3.0 1.5 0.3 1.2 Dipped 4.6 4.4 4.6 4.2 3.4 3.2 3.4 3.0 2.4 1.5 1.0 2.2 1.0 1.3 1.5 A =: Appearance F = Flavor T =: Texture 2.0, and 2.3, respectively, for glazed fillets, and 1.5, 1.0, and 1.8, respectively, for whole heads- off control samples. In some instances, control fillets packed in vacuum received better scores than samples treated with antioxidant mixtures not packed in vacuum. After 9 months' storage Table 3. — Organoleptic scores of glazed whole heads-off Spanish mackerel {Scomberomorus maculatus). 2 weeks 2 months 3 months 6 months 9 months AFT AFT AFT AFT AFT Control 4.2 4.4 4.2 3.6 4.0 4.6 4.0 3.8 3.8 3.6 Tenox 4: Injected 4.2 4.2 4.2 4.4 3.8 4.6 4.0 4.0 4.8 3.4 Dipped 4.0 3.8 4.4 3.8 3.8 4.2 3.8 2.2 3.4 2.8 Tenox 6: Injected 3.8 3.4 4.0 3.6 3.4 3.4 4.0 3.4 3.8 3.0 Dipped 4.4 4.6 4.6 4.4 4.0 4.6 4.2 3.0 3.4 3.6 EDTA: Injected 4.2 3.8 4.4 3.8 2.8 3.6 3.4 2.8 3.0 2.6 Dipped 4.4 4.6 4.4 3.8 3.8 4.2 3.6 2.4 3.6 3.2 Tenox 4 + EDTA: Injected 4.2 4.5 4.4 4.0 3.8 4.8 4.2 4.0 4.0 3.4 Dipped 4.0 3.2 4.2 3.6 3.0 2.6 4.0 3.0 3.0 2.6 Tenox 6 + EDTA: Injected 4.4 3.4 4.4 3.8 3.8 4.2 3.6 3.0 3.0 2.8 Dipped 4.4 4.6 4.6 4.2 4.4 3.8 4.0 3.6 3.6 3.6 A = Appearance F = Flavor T =: Texture 3.0 1.5 1.0 1.8 3.2 4.0 2.0 1.7 2.0 2.4 2.4 1.3 1.3 2.1 3.0 3.0 1.6 1.7 2.3 3.2 3.6 0.8 1.3 1.6 2.2 2.2 3.2 3.0 2.7 3.6 3.4 3.2 3.0 2.7 3.4 3.6 2.7 0.7 2.2 2.6 3.2 2.5 2.3 2.2 2.2 2.4 2.2 2.7 2.5 3.2 3.6 1.7 1.3 2.2 most samples treated with Tenox 4 and Tenox 6 did not receive organoleptic scores equaling the control (Tables 1, 2, 3). Rancidity was observed by the taste panel in most samples not packed in vacuum between the third and sixth month. Severe discolor- ation usually preceded the detection of ran- cidity by several weeks in samples treated with mixtures of antioxidants. This discoloration was exhibited by a general darkening of the flesh in the controls and a yellowish hue in samples treated with Tenox 4 and Tenox 6. Samples treated with EDTA, however, did not develop any rancid off-flavors during the stor- age period. Figure 1 shows a typical flavor curve describ- ing deterioration of flavor in vacuum-packed fillets during frozen storage. The Tenox 6 curve is typical of data obtained from samples treated with mixtures of the various antiox- idants. Control fillets packed in vacuum show a more or less steady decline in flavor through- out the storage period (Table 1 ) . The scoi-es of samples treated with Tenox 6 decreased un- evenly from 4.0 to 2.25 (Table 1). The flavor curve of fillets treated with EDTA and packed in vacuum remains higher than the controls from the third month to the ninth month (Table 1) . At the third month, or about the time ran- cidity was first noticed in some samples, the control and Tenox 6 treated samples showed a slight increase in averaged scores. The evaluation of texture by the taste panel throughout the storage period showed inter- esting results. Typical curves can be seen in Figure 2. The texture of the controls dropped in the ratings from 4.0 to 3.4 after 3 months' storage whpre it remained until the sixth month. Samples treated with Tenox 6 were rated superior to the controls in texture through Control - Tenox 6" EDTA 4 S TIM! (MONTHS! Figure 1. — Organoleptic score for flavor of Spanish mackerel fillets. . 10 9 ■ \ '^■^.^ ""*.. O 2 7 z I* ?3 Control Tenox 6 ' EDTA i^ J • ■ 1 2 3 4 5 6 7 TIME IMONTHSI 8 9 Fi^re 2. — Organoleptic score for texture of Spanish mackerel fillets. the sixth month but fell below the controls on the ninth month. EDTA-treated samples re- mained superior to the controls in texture from the third to the ninth month. Samples treated with Tenox 4 plus EDTA and Tenox 6 plus EDTA, regardless of packaging technique and application method, scored the lowest in tex- ture after 9 months' storage (Tables 1, 2, 3). Peroxide content of the test pack generally followed the curves shown in Figure 3. Sam- ples treated with Tenox 6 remained lower in peroxides than the controls or samples treated with EDTA (Tables 4, 5, 6). The initial in- crease of peroxides in the controls reached a 4 5 6 TIME IMONTHSI Figure 3. — Peroxide content of the oil fraction from Spanish mackerel. high point in the third month (9.90 milliequiva- lents/1000 g) then decreased (3.60 milliequiva- lents/1000 g) in the sixth month. A large fluc- tuation in the peroxide content of the control samples continued throughout the test period (Tables 4, 5, 6). Samples treated with antiox- idants or EDTA initially increased in peroxide content then remained static through the sixth month. Samples treated with Tenox 6 decreased in peroxide content after the sixth month period coinciding with increasing rancid ofl^-flavors de- velopment. EDTA-treated samples increased in peroxide content after the sixth month period Table 4. — Peroxide content of Spanish mackerel (Scomberomorus maculatxLs) packed in vacuum-sealed bags. 2 weeks 2 months 3 months 6 months 9 months Control 2.50 Tenox 4: Injected 3.00 Dipped 3.34 Tenox 6: Injected Dipped 1.54 EDTA: Injected 3.30 Dipped 3.62 Tenox 4 + EDTA: Injected 3.10 Dipped 1.96 Tenox 6 + EDTA: Injected 2.90 Dipped 1.70 miHiequivatents/lOOO grams 6.60 10.92 3.60 7.22 4.04 4.20 3.04 6.14 5.34 5.80 4.72 5.00 4.90 3.76 17.50 6.14 2.70 3.30 4.04 4.40 4.50 4.40 3.52 11.48 10.22 9.34 9.00 2.56 12.00 15.10 4.00 4.40 6.50 9.14 14.25 3.02 4.62 1.14 4.92 5.05 2.46 2.60 1.72 4.20 Table 5. — Peroxide content of glazed Spanish mackerel (Scomberomorus niaculatus) fillets. 2 weeks 2 months 3 months 6 months 9 months Control 1.80 Teno.x 4: Injected 2.42 Dipped 2.50 Tenox 6: Injected 3.00 Dipped 2.18 EDTA: Injected 3.20 Dipped 6.52 Tenox 4 + EDTA: Injected 3.90 Dipped 4.12 Tenox 6 + EDTA: Injected 3.70 Dipped 1.74 ynilliequivalents/lOOO grams 17.80 24.17 9.10 21.60 11.72 12.00 3.30 48.80 8.70 10.60 3.18 29.80 8.84 12.20 18.12 20.60 6.70 10.72 3.58 14.80 5.00 12.00 4.32 4.92 8.74 17.10 7.22 33.40 16.87 7.80 5.40 16.65 14.50 13.84 11.60 13.65 10.66 14.92 9.20 9.60 6.04 8.70 9.90 _. Table 6. — Peroxide content of glazed whole heads-off -Spanish mackerel {Scomberoynorus macidatus) . 2 weeks 2 months 3 months 6 months 9 months viiUieqidvalents/ 1000 grams Control 3.30 Tenox 4: Injected 3.60 Dipped 2.30 Tenox 6: Injected 6.92 Dipped 3.88 EDTA: Injected 3.84 Dipped 5.25 Tenox 4 + EDTA: Injected 3.70 Dipped 2.60 Tenox 6 + EDTA: Injected 3.22 Dipped 3.62 8.10 5.66 16.80 13.36 8.02 9.02 18.90 41.30 9.00 14.50 30.62 16.94 6.84 9.98 11.52 15.42 7.60 10,30 3.40 30.50 11.40 3.22 20.90 33.50 4.70 11.55 12.70 18.12 8.74 6.80 24..38 19.30 10.86 11.37 15.10 22.80 7.56 2.60 20,.50 18.85 7.56 9.48 15.08 29.00 but no rancid off -flavors or odors were detected. The free fatty acid content of the controls, Tenox 6, and EDTA-treated samples are shown in Figure 4. Samples treated with Tenox 4 and antioxidants plus EDTA showed similar curves (Tables 7, 8, 9). The free fatty acid content of the test pack varied considerably throughout the experiment. Samples treated with Tenox 6 increased steadily in free fatty acid content until the third month then rose steadily to the ninth month. DISCUSSION The variables that were compared through- out the experiment included (1) methods of applying the antioxidants and EDTA and (2) the packaging method (vacuum-packaging compared to glazing). Samples dipped or in- jected showed the same trends in peroxide and free fatty acid content throughout the exper- iments. Organoleptic evaluation of these sam- ples was almost identical. 7 6 / / 5 ^____ • .....■■■■■■■■■■■■■ tL .,..-■■ *J 4 m A / ...-" < z •-" u 3 »i .,._ / y ■--.., / '' ■■■■""" Control •^ 1 y ly Tenox 6 ? ,'■/ 1 ■ •4 5 6 TIMEIMONTHSI Figure 4. — Free fatty acid content of the oil fraction from Spanish maclverel fillets. A difference in organoleptic scores between samples packed in vacuum or glazed was noted throughout the storage period. Samples packed in vacuum were rated organoleptically superior to glazed samples (Tables 1, 2, 3). Samples treated with Tenox 4, Tenox 6, Tenox 4 plus EDTA, and Tenox 6 plus EDTA develo])ed rancid flavors and odors after 6 months' frozen storage. Peroxide and FFA content of samples treated with these com- pounds did not correlate with the rancid flavors and odors that developed. This would indicate a deterioration similar to the observations of Ca.stell et al. (1965), who reported that many off -odors are not usually identified with the de- velopment of oxidative rancidity. Castell et al. found that a considerable diffei'ence occurred in early developing off -odors when rancidity was activated by different chemical compounds, and they observed a different off-odor associ- ated with the addition of different trace min- erals. Castell et al. concluded that the mixture of trace minerals on fish acquired through en- vironment and handling could account for the varied off-odors from deterioration found in commercial samples. Castell and Spears (1968) observed a rapid increase in rancidity development with the ad- dition of minute quantities of trace minerals. Table 7. — Free fatty acid content of Spanish mackerel (Scomberomorus maculatus) fillets packed in vacuum-sealed bags. 2 weeks 2 months 3 months 6 months 9 months Control % oleic 1.55 Tenox 4: Injected 1.25 Dipped 1.12 Tenox 6: Injected Dipped 1.46 EDTA: Injected 2.58 Dipped 2.98 Tenox 4 + EDTA: Injected 1.25 Dipped 1.35 Tenox 6 + EDTA: Injected 1.24 Dipped 1.31 % oleic 1.54 2.54 1.85 1.89 1.85 2.11 2.61 1.80 1.94 2.79 2.45 % oleic 4.15 3.04 6.21 3.16 2.73 2.44 2.54 3.56 4.26 2.56 2.62 % oleic 4.60 6.00 3.51 3.92 6.65 8.46 8.84 9.93 3.87 4.75 7.63 % oleic 4.45 7.61 3.70 4.48 12.51 5.78 5.21 8.37 7.00 10.76 7.05 Table 8. — Free fatty acid content of Spanish mackerel (Scomberomorus maculatns) glazed fillets. 2 weeks 2 months 3 months 6 months 9 months Control % oleic 0.62 Tenox 4; Injected 1.33 Dipped 1.74 Tenox 6: Injected 2.64 Dipped 2.00 EDTA: Injected 0.99 Dipped 1.87 Tenox 4 + EDTA: Injected 1.21 Dipped 1.70 Tenox 6 + EDTA: Injected 2.97 Dipped 1.65 % oleic 2.21 2.39 2.03 2.07 1.58 2.53 3.33 4.82 1.85 1.82 4.08 % oleic 6.15 3.81 4.37 3..39 3.22 2.99 2.80 3.78 2.91 3.23 3.89 % oleic 2.45 3.95 4.05 3.58 6.08 2.63 7.38 3.70 6.01 4.18 4.61 % oleic 6.66 4.35 4.54 4.38 6.54 12.47 S.05 6.69 6.27 5.70 5.84 Table 9. — Free fatty acid content of glazed whole heads-off Spanish mackerel (Scombei-omorus maculatus) . 2 weeks 2 months 3 months 6 months 9 months Control % oleic 1.33 Tenox 4: Injected 1.80 Dipped 1.67 Tenox 6: Injected 2.72 Dipped 1.09 EDTA: Injected 1.49 Dipped 1.98 Tenox 4 + EDTA: Injected 1.08 Dipped 0.94 Tenox 6 + EDTA: Injected 1.29- Dipped 1.44 % oleic 2.14 2.16 2.13 3.07 2.47 1.70 3.38 2.11 2.10 2..37 2.69 % oleic 2.75 3.64 2.57 2.74 4.37 3.90 5.21 1.92 5.40 2.57 4.22 % oleic 5.58 5.21 5.01 3.65 3.56 4.78 2.36 5.82 4.55 4.23 4.81 % oleic 4.24 9.41 5.17 5.58 6.91 7.51 4.63 5.92 5.08 6.09 8.11 The addition of a chelating compound such as EDTA would decrease the amount of trace min- erals available. However, the chelation of trace minerals did not affect the initial production of peroxides and free fatty acid. The development of rancidity in Spanish mackerel during frozen storage was retarded by the application of EDTA. The only criti- cism received by these samples from the taste panel throughout the storage period was in their appearance. A yellowish discoloration developed on and adjacent to the belly flap after the si.xth month of storage. The concentration of EDTA applied to the sample may be a factor in the development of this discoloration. Addi- and different tional experiments using various salts of EDTA Part II. concentrations is described in Part II. THE EFFECT OF VARIOUS EDTA COMPOUNDS UPON TEXTURE AND THE DEVELOPMENT OF RANCIDITY IN SPANISH MACKEREL FILLETS MATERIALS AND PROCEDURE Spanish mackerel were purchased locally with the exact age and area of capture being unknown. The overall condition of the fish was considered to be better than the average com- mercial samples. Samples were filleted and then dipped or injected with 250 ppm, 180 ppm, and 125 ppm of the following compounds: EDTA (ethylenediaminetetraacetic acid), Ca(Na)2EDTA (disodium calcium ethylenedi- aminetetraacetate) , (Na)2EDTA (disodium ethylenediaminetetraacetate) , (Na) 4EDTA (tetrasodium ethylenediaminetetraacetate), and (Ca)2EDTA (dicalcium ethylenediamine- traacetate). The parameters for dipping and injecting were the same reported in Part I. After treatment all samples were packed in vacuum and stored at — 10° F until analyzed. All EDTA compounds were obtained from East- man Organic Chemical Co. Samples were analyzed every 3 months for peroxide content, free fatty acid content, and organoleptically as previously stated. RESULTS The development of free fatty acids adhered to the same general pattern observed in Part I of this experiment for EDTA-treated fillets. Samples treated with (Na)4EDTA and (Na)2- EDTA remained lower in free fatty acid con- tent after 12 months of frozen storage than did samples treated with other compounds. Two samples surpassed the 6.88 'r free fatty acid as oleic found in the control at the 12th month. One sample was injected with 250 ppm (Na)2- EDTA, one with 125 ppm (Na)4EDTA (Table 10). The concentration of additive that appeared to best protect the fillets against free fatty acid formation was dependent upon the method of application (Fig. 5). Fillets dipped in (Na).,- EDTA at the 180 ppm level remained lower in free fatty acid content throughout the storage period than did samples dipped in 250 ppm or 125 ppm level (Table 10). Samples injected with (Na)2EDTA at the 125 ppm level were better protected against free fatty acid forma- tion than samjiles injected with higher concen- trations of (Na)2EDTA (Table 10). Samples treated with (Na)4EDTA followed the same ]3attern of free fatty acid development as those treated with (Na^EDTA. Thus, after 12 months of frozen storage, fillets dipped or in- jected with 180 ppm (Na)4EDTA remained lower in free fatty acid content than the other samples treated with (Na)4EDTA (Table 10). Fillets dipped at the 125 ppm level in four of the five tested compounds remained lower in free fatty acid content than did the respective injected samples (Table 10). Those fillets in- jected with (Ca)2EDTA at the 180 ppm level were lower in free fatty acid content as oleic than (Ca)2EDTA dipped samples and were the exception to the rule (Table 10). In short, the samples remaining lowest in free fatty acid content after 12 months' frozen storage were those treated with 180 ppm or 125 ppm of each of the respective compounds. Sam- ples treated with 250 ppm of EDTA and its salts 8 ■■■ 6 ""-y^ T^'^^^-^i ColNoljEDTA-.- / .-' V- > ><" / 54 7 INaljEDTA ^^ -—' (ColjEDTA 0 Control TIME (MONTHI Figure 5. — Free fatty acid content of the oil from Spanish mackerel fillets treated with 180 ppm of EDTA and certain salts of EDTA. Table 10. — Fatty acid content of Spanish mackerel {Scomberomorus maculatiis) packed in vacuum-sealed bags. Di pped Inje :ted 3 months 6 months 9 months 12 months 3 months 6 months 9 months 12 months % oleic % oleic % oleic % oleic % oleic % oleic % oleic % oleic Control 2,81 6,35 6.81 6.88 — -- — — EDTA: 250 ppm 2.81 4.67 6.26 5.85 19.56 5.38 4.74 7.69 180 ppm 5,89 5,01 2.40 5.77 __ 4.61 4.74 6.10 125 ppm 2,04 3,68 5.93 4.03 — 4.44 5.65 5.17 Ca(Na)2EDTA: 250 ppm 5,29 10.60 6.16 4.31 6.26 4.81 180 ppm 2,95 2.92 5.85 4.96 4.61 3.40 5.92 4.31 125 ppm 3,32 -- 6.03 4,30 5.09 3.66 3.63 5.88 (Na)2EDTA: 250 ppm 10.02 4.24 5.61 9,25 2.12 2.44 4.31 4.36 180 ppm 35,90 3.54 5.62 4,96 2.04 4.39 5.84 5.72 125 ppm 2,01 3.25 5.44 3.51 3.03 3.52 4.89 4.09 (Na)4EDTA: 250 ppm 7,23 6.00 5.98 6.77 2.09 3.35 5.54 4.66 180 ppm 1,96 2.87 4.49 4.01 2.68 3.60 5.71 4.03 125 ppm 2,06 6.70 3.99 7.96 2.22 4.80 4.82 — (Ca)2EDTA: 250 ppm 3,21 4.48 4.16 6.71 2.41 4.56 6.27 4.94 180 ppm 2,95 4.34 4.74 6.63 2.22 3.02 4.28 3.71 125 ppm 2,54 — 8.12 4.01 2.09 4.45 5.17 5.58 showed the highest free fatty acid content at the end of the storage period. Fillets dipped with 180 ppm of (Na)2EDTA, (Na)4EDTA, and (Ca)2EDTA were lower in peroxide content than samples injected with these compounds after 12 months' frozen stor- age (Table 11) . The peroxide formation in the samples increased up to the ninth month. A de- crease in peroxide content from the ninth month to the 12th month was noted (Table 11) . The concentration of the various compounds used affected the peroxide content. Samples dipped with 180 ppm of (Na)2EDTA were found to have the lowest peroxide content after 12 months of frozen storage (Table 11). Pe- roxide formation was best retarded in these samples treated with 180 ppm of these com- pounds. The organoleptic texture scores of samples dipped in 180 ppm of the various compounds can be seen in Figure 6 and Table 12. After 6 months of storage, the taste panel rated these samples in the range of 2.8 (EDTA) to 4.0 [ ( Na) aEDTA] . Scores for these samples af tei 12 months of frozen storage were below 3.0. Three of the five samples treated with the dif- ferent compounds, however, were rated equal to or better than the control in texture after 12 months of storage. These were those treated at the 180 ppm level of (Ca)2EDTA, (Na)2EDTA, and (Na)4EDTA, and 125 ppm of (Ca)2EDTA, ( N a )4 E D T A , an d Ca(Na)2EDTA. 5 4 EDTA f^-' ^ ' '♦- 3 DC 5' UJ ColNoljEDTA INaljEDTA - ""*•*** I INal^EDTA — - ColjEDTA — Control - 6 9 TIME IMONTHSI Figure 6. — Organoleptic score for texture of Spanish mackerel fillets treated with 180 ppm of EDTA and certain salts of EDTA. 10 Table 11. — Peroxide content of Spanish mackerel {Scomberomorus maculatus) packed in vacuum-sealed bags Dipped 3 months 6 months 9 months 12 months Injected 3 months 6 months 9 months 12 months Control milliequivalents/ 1000 grams 10.05 10.85 82.41 14.96 milliequ ivalen ts/1 000 grams EDTA: 250 ppm 0.00 8.37 180 ppm 0.00 9.54 125 ppm 37.58 6.43 Ca(Na)2EDTA: 250 ppm -- 11.26 180 ppm 23.91 5.43 125 ppm 8.84 (Na)2EDTA: 2513 ppm 0.00 5.02 180 ppm — 8.44 125 ppm 20.30 6.03 (Na)4EDTA: 250 ppm 3.81 7.04 180 ppm 2.41 5.02 125 ppm 12.66 8.04 (Ca),EDTA: 25^0 ppm 16.28 7.37 180 ppm — 7.54 125 ppm 9.44 14.82 9.95 43.90 59.09 115.58 10.07 5.89 75.40 38.59 57.48 43.64 51.05 88.26 56.64 12.76 14.27 18.84 12.16 14.87 27.64 18.71 16.70 5.43 12.76 15.00 12.46 24.12 16.75 15..33 15.56 0.00 7.43 0.00 8.24 8.24 5.02 7.43 7.43 12.66 12.46 2.01 5.02 7.54 6.23 6.03 4.02 4.22 6.28 4.02 5.02 3.62 6.36 8.04 8.04 21.86 13.75 9.55 80.24 107.03 69.91 18.37 67.33 125.83 47.84 52.06 40.10 38.79 56.66 38.55 8.80 17.77 9.25 15.28 12.56 13.71 27.09 19.70 13.03 11.07 14.67 13.87 16.18 21.55 21.51 Table 12.- — Texture scores of Spanish mackerel (Scomberomorus maculatus) packed in vacuum-sealed bags. Dipped Injected 3 months 6 months 9 months 12 months 3 months 6 months 9 months 12 months Control 3.3 EDTA: 250 ppm 3.1 180 ppm 3.1 125 ppm 3.1 Ca(Na)2EDTA: 250 ppm 3.3 180 ppm 2.9 125 ppm 2.7 (Na)2EDTA: 250 ppm 3.4 180 ppm 3.3 125 ppm 3.0 (Na)4EDTA: 250 ppm 2.1 180 ppm 2.4 125 ppm 3.1 (Ca)2EDTA: 2.50 ppm 2.7 180 ppm 2.7 125 ppm 2.8 3.3 1.9 3.3 3.3 1.9 3.1 2.6 1.9 2.5 2.6 2.6 1.9 2.8 2.2 1.6 3.0 2.6 2.2 1.6 3.1 2.6 1.6 3.0 2.5 2.6 1.9 3.1 2.8 1.6 3.5 3.5 3.0 1.9 3.5 2.8 1.6 3.7 3.3 3.2 1.6 2.3 2.8 1.9 3.4 3.8 2.8 1.9 3.3 2.8 1.9 3.0 3.5 2.8 1.6 4.0 2.8 1.9 2.5 3.8 2.4 1.6 3.8 2.2 1.6 2.5 2.8 3.0 1.9 3.1 2.8 1.9 3.7 3.3 3.2 1.9 4.0 2.8 2.6 3.5 3.5 3.4 2.9 3.5 3.0 2.9 3.3 3.6 3.4 1.9 4.1 2.4 1.6 2.8 2.8 3.0 1.9 3.1 2.6 1.9 3.1 3.6 2.8 2.9 3.6 __ 2.9 2.8 3.8 3.0 2.9 11 DISCUSSION Spanish mackerel fillets were treated with EDTA and four of its salts, vacuum packaged, and tested for the development of rancidity and toug^h texture. Analysis of free fatty acids and peroxides as well as orgfanoleptic evalua- tion did not reveal the development of rancidity in any of the samples treated with (Na) 2EDTA or (Na),EDTA. The evaluation of data ob- tained from these analyses showed that several of these compounds, which are chemically closely related, protected Spanish mackerel fillets from discoloration and ofi'-odors more eff'ectively than others. Although free fatty acids were found in ir- regular concentration throughout the storage period, those samples dipped in 180 ppm (Na)4- EDTA were 2.87''r lower in free fatty acid content than the controls (Table 10). Castell and Spears (1968) showed that the degradation of fish oil is directly related to available trace minerals. The addition of (Na)4EDTA to Spanish mackerel fillets apparently reduced the amount of free trace minerals resulting in a much slower breakdown of triglycerides and lower peroxide content than normal. Peroxide values varied considerably for each sample throughout the storage period. How- ever, some generalizations can be made. A sharp increase in peroxide values occurred be- tween the third month and the ninth month, after which decreases of diff'erent magnitudes were noted for all samples (Table 11). Two compounds, (Na)2EDTAand (Na)4EDTA, ap- peared to restrict the development of peroxides more effectively than the others. Free fatty acid and peroxide values are not necessarily related to the absence or presence of rancidity. These analyses are indicators of the chemical degradation of the oil in the sam- ples. Other chemical tests, such as TBA, also measure the chemical reactions occurring. In the final analysis, the only true evaluation of rancidity is its detection by a trained taste pan- el. Typical rancid odor and off -flavors did not develop in any sample during the storage per- iod. Since the taste panel noticed the devel- opment of a woody texture in the fillets treated with EDTA in Part I, this experiment was designed to ascertain differences in texture which might result from the use of various salts of the parent EDTA. The taste panel pre- ferred the texture of samples treated with (Na)2EDTA and (Na)4EDTA to samples treated with other compounds or the controls (Table 12). The general opinion of the panel was that these samples were not equal to fresh mackerel fillets but that they were superior to the other samples or to commercially frozen mackerel fillets. Power et al. (1968) reported similar results from (Na)2EDTA and (Na)4EDTA dipped haddock fillets stored in ice. Haddock fillets dipped in 0.59 and 0.75^ (Na)4EDTA were rejected because of extreme tough texture. However, samples dipped in l.C^r (Na)4EDTA remained acceptable throughout the experi- ment. Power found that although the texture in these fillets was not equal to fresh fillets it was not objectionable. The observed changes in the texture of Spanish mackerel fillets treated with EDTA salts, although not objec- tionable, remain a mystery. Chemical or other pathways by which these changes occur are at this point speculation. LITERATURE CITED AMERICAN OIL CHEMISTS' SOCIETY. 1964. Official and tentative methods of the Amer- ican Oil Chemists' Society. Second ed. Amer- ican Oil Chemists' Society, Chicago, 111. CASTELL, C. H., J. MACLEAN, and B. MOORE. 1965. Rancidity in lean fish muscle. IV. Effect of sodium chloride and other salts. Fish. Res. Board Can. 22: 929-944. CASTELL, C. H., and D. M. SPEARS. 1968. Heavy metal ions and the development of rancidity in blended fish muscle. Fish. Res. Board Can. 25: 639-656. LYLES, C. H. 1969. The Spanish mackerel and king mackerel fisheries. U.S. Fish Wildl. Serv., C.F.S. No. 49.36, ii + 21 p. POWER, H. E., R. SINCLAIR, and K. SARAGAON. 1968. Use of EDTA compounds for the preser- vation of haddock fillets. Fish. Res. Board Can. 25: 2071-2082. TARR, H. L. A. 1947. Control of rancidity in fi.sh flesh. Fish. Res. Board Can. 7: 137-154." VOSS, J., and W. MUNKMER. 1966. On the application of antioxidants and bac- tericidal substances during storage of herring fillets in ice. Fischerei-Forschung 4(4) : 73-84. 12 GPO 999-694 MBL WHOI Library - Serials 5 WHSE 01830 621. Predation by sculpins on fall chinook salmon, Oiicorhynchus tshrtwytscha, fry of hatchery or- igin. By Benjamin G. Patten. February 1971, iii + 14 pp., 6 figs., 9 tables. 622. Number and lengths, by season, of fishes caught with an otter trawl near Woods Hole, Massa- chusetts, September 1961 to December 1962. By F. E. Lux and F. E. Nichy. February 1971, iii -|- 15 pp., 3 figs., 19 tables. 623. Apparent abundance, distribution, and migra- tions of albacore, Thnunus alalunga, on the North Pacific longline grounds. By Brian J. Rothschild and Marian Y. Y. Yong. September 1970, v + 37 pp., 19 figs., 5 tables. 624. Influence of mechanical processing on the quality and yield of bay scallop meats. Bv N. B. Webb and F. B. Thomas. April 1971, iii + 11 pp., 9 figs., 3 tables. 625. Distribution of salmon and related oceanographic features in the North Pacific Ocean, spring 1968. By Robert R. French, Richard G. Bakkala, Ma- sanao Osako, and Jun Ito. March 1971, iii + 22 pp., 19 figs., 3 tables. 626. Commercial fishery and biology of the fresh- water shrimp, MacrobrachitDii, in the Lower St. Paul River, Liberia, 1952-53. By George C. Mil- ler. February 1971, iii -)- 13 pp., 8 figs., 7 tables. 627. Calico scallops of the Southeastern United States, 1959-69. Bv Robert Cummins, Jr. June 1971, iii + 22 pp., 23 figs., 3 tables. 628. Fur Seal Investigations, 1969. By NMFS, Ma- rine Mammal Biological Laboratorv. August 1971, 82 pp., 20 fig.s., 44 tables, 23 appendix A tables, 10 appendi.x B tables. 629. Analysis of the operations of seven Hawaiian skipjack tuna fishing vessels, June-August 1967. By Richard N. Uchida and Ray F. Sumida. March 1971, v + 25 pp., 14 figs., 21 tables. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - 35 cents. 630. Blue crab meat. I. Preservation bv freezing. July 1971, iii + 13 pp., 5 figs., 2 tables' II. Effect of chemical treatments on acceptability. By Jurgen H. Strasser, Jean S. Lennon, and Fred- erick J. King. July 1971, iri -|- 12 pp., 1 fig., 9 tables. 631. Occurrence of thiaminase in some common aquat- ic animals of the United States and Canada. By R. A. Greig and R. H. Gnaedinger. July 1971, iii + 7 pp., 2 tables. 632. An annotated bibliography of attempts to rear the larvae of marine fi.shes in the laboratory. By Robert C. May. August 1971, iii -|- 24 pp., 1 ap- pendix I table, 1 appendix II table. For sale by the Superintendent of Documents, U.S. Govern- ment Printing Oflice, Washington, D.C. 20402 - 35 cents. 633. Blueing of processed crab meat. II. Identification of some factors involved in the blue discoloration of canned crab meat Callincctes sapidus. By Melvin E. Waters. May 1971, iii + 7 pp., 1 fig!, 3 tables. 634. 635. 636. 637 638. 639. 640. 641. 642. 646. Age composition, weight, length, and sex of her- ring, Clnpea paUasii, used for reduction in Alas- ka, 1929-66. By Gerald M. Reid. July 1971, iii + 25 pp., 4 figs., 18 tables. A bibliography of the blackfin tuna, Tku)t7ius atlanticus (Lesson). By Grant L. Beardsley and David C. Simmons. August 1971, 10 pp. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - 25 cents. Oil pollution on Wake Island from the tanker R. C. Stover. By Reginald M. Gooding. May 1971, iii + 12 pp., 8 figs., 2 tables. For sale by the Superintendent of Documents, U.S. Govern- ment Printing Oflice, Washington, D.C. 20402 - Price 25 cents. Occurrence of larval, juvenile, and mature crabs in the vicinity of Beaufort Inlet, North Carolina. By Donnie L. Dudley and Mayo H. Judv. August 1971, iii + 10 pp., 1 fig., 5 tables. F'or sale by the Superintendent of Documents, U.S. Govern- ment Printing Office, Washington, D.C. 20402 - Price 25 cents. Length-weight relations of haddock from com- mercial landings in New England, 1931-55. By Bradford E. Brown and Richard C. Hennemuth. August 1971, v -f 13 pp., 16 fig., 6 tables, 10 appendix A tables. For .sale by the Superintend- ent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price 25 cents. A hvdrographic survey of the Galveston Bay system, Texas 1963-66. By E. J. Pullen, W. L. Trent, and G. B. Adams. October 1971, v -|- 13 pp., 15 figs., 12 tables. For sale by the Super- intendent of Documents, U.S. Government Print- ing Office, Washington, D.C. 20402 - Price 30 cents. Annotated bibliography on the fishing industry and biology of the blue crab, Callinectes sapidtis. By Marlin E. Tagatz and Ann Bowman Hall. August 1971, 94 pp. For sale by the Superinten- dent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $1.00. Use of threadfin shad, Dorosomu petenense, as live bait during experimental pole-and-line fish- ing for skipjack tuna, h'atsuwonus pelamis, in Hawaii. By Robert T. B. Iversen. August 1971, iii + 10 pp., 3 figs., 7 tables. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price 25 cents. Atlantic menhaden Brevoortia tyrannus resource and fishery — analysis of decline. By Kenneth A. Henry. August 1971, v + 32 pp., 40 figs., 5 appendix figs., 3 tables, 2 appendix tables. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price 45 cents. Dissolved nitrogen concentrations in the Colum- bia and Snake Rivers in 1970 and their eff^ect on chinook salmon and steelhead trout. By Weslev J. Ebel. August 1971, iii -|- 7 pp., 2 figs., (5 tables. For sale by the Superintendent of Doc- uments, U.S. Government Printing Office, Wash- ington, D.C. 20402 - Price 20 cents. UNITED STATES DEPARTMENT OF COMMERCE NATIONAL OCEANIC & ATMOSPHERIC ADMINISTRATION NATIONAL MARINE FISHERIES SERVICE SCIENTIFIC PUBLICATIONS STAFF BLDG. 67, NAVAL SUPPORT ACTIVITY SEAHLE, WASHINGTON 98115 OFFICIAL BUSINESS POSTAGE AND FEES PAID U.S. DEPARTMENT OF COMMERCE