EFFECTS OF COOKING IN AIR OR IN NITROGEN ON THE 



DEVELOPMENT OF FISHY FLAVOR IN THE BREAST MEAT 



OF TURKEYS FED TUNA OIL WITH AND WITHOUT 



a-TOCOPHEROL SUPPLEMENT OR INJECTION 



L. Crawford and M. J. Kretsch^ 



ABSTRACT 



The breast meat of turkeys which had been fed fish oil with and without a-tocopherol supplement or 

 injection were cooked in air or under nitrogen with a slight vacuum. Cooking under nitrogen 

 prevented the development of fishy flavor nearly as well as dietary a-tocopherol acetate supplementa- 

 tion. Some evidence is given which shows that fishy fiavor develops postmortem (during cooking) and 

 not in vivo. 



Crawford et al. (1974) explored the effects of 

 feeding fish oil with and without a-tocopherol 

 acetate on the flavor of turkeys. This paper and 

 other work by Crawford et al. (1975) showed 

 that dietary a-tocopherol can be very effective in 

 preventing the development of fishy flavor Simi- 

 larly, a-tocopherol acetate had a profound effect 

 on the "elimination" of fishy flavor when it and 

 beef fat were substituted for fish oil in the rations 

 of turkeys that had been fed diets containing fish 

 oil for several weeks. Injection of a-tocopherol (a 

 few days before slaughter) into the thighs of 

 turkeys fed diets containing fish oil showed a 

 positive effect on the reduction of fishy flavor. 



Consideration of these results and the finding 

 that poultry carcass stability is related to the 

 degree of lipid unsaturation and the tocopherol 

 content (Mecchi, Pool, Behman, Hamachi, and 

 Klose 1956; Mecchi, Pool, Nonaka, Klose, Mars- 

 den, and Lillie 1956; Webb, Brunson, and Yates 

 1972, 1973; Webb, Marion, and Hayse 1972) 

 led us to the reasoning that flshy flavor in poultry 

 may result from in vivo and/or postmortem oxida- 

 tion of lipids containing long chain a>-3 fatty 

 acids. Crawford et al. (1975) entertained the 

 possibility that such oxidation and subsequent 

 fishy flavor development occur mostly in vivo. At 

 first glance, the effects of dietary a-tocopherol 

 acetate on prevention of fishy flavor seem to 

 support this hypothesis. However, the effective- 

 ness of injecting a-tocopherol only a few days 

 before slaughter casts some doubt on this reason- 



'Western Regional Research Laboratory, Agriculture Re- 

 search Service, U.S. Department of Agriculture, Berkeley, CA 

 94710. 



Manuscript accepted June 1975. 



FISHERY BULLETIN: VOL. 74, NO. 1, 1976. 



ing since in vivo oxidation prior to injection 

 should have had ample time to occur. Whereas 

 this doubt does not call for total apostasy, it does 

 suggest that postmortem oxidation and sub- 

 sequent development of fishy flavor is indeed a 

 possibility and deserves consideration. 



The exact nature and origin of flshy flavor in 

 turkeys is not known, but it is known that the 

 development of such flavor requires the uptake of 

 oi-S fatty acids from dietary oils rich in these fatty 

 acids. Most fish oils are rich sources of long 

 chained w-3 fatty acids which are readily taken 

 up into the carcass of turkeys when included in 

 their diet. Linseed oil contains more than 50% 

 linolenic acid and when incorporated into turkey 

 diets, the linolenic acid is taken up and elongated 

 to the longer chained homologues thereby caus- 

 ing fishy flavor to develop (-Klose et al. 1951; 

 Miller et al. 1967a, b; Crawford et al. 1974). 



If postmortem oxidation plays a major role in 

 the development of fishy flavor, it is likely that 

 the development would occur largely during cook- 

 ing. Pippen and Nonaka (1963) found that the 

 amount of volatiles from raw chicken was small 

 and the aroma rather insipid when compared to 

 the relatively large amount of highly odoriferous 

 volatiles from cooked chicken. They also reported 

 that chicken boiled in air yielded a more complex 

 and larger volatile fraction than chicken boiled in 

 nitrogen. Crawford (1972) reported that replace- 

 ment of air in the headspace with nitrogen gave 

 some protection against scorch during the retort- 

 ing of 4-pound cans of tuna. This suggests that 

 less carbonyls (volatiles) were formed under ni- 

 trogen since volatile carbonyls, sugars, and 



89 



