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 

 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, 



