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 



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. 



