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 



