Table 1. — A comparison of lipids extracted from several fish protein concentrates. 



'Number of carbon atoms: number of double bonds. Additional fatty acids, tentatively identified but present in amounts of 1% or less, were: 

 12:0. anteiso 15:0. iso 16:0. 16:2. 18:3, 19:0, iso 20:0. 20:2, 20:3, 21:0, 22:2, 22:3, 22:4, 24:1. 

 ^Dry basis 



The percentages of volatile matter in the Pacific 

 hake (78-103) samples stored at different tempera- 

 tures and humidities are shown in Table 2. The 

 moisture content of the different samples was 

 relatively constant during several month's storage 

 in plastic bags at -18°C. The increase in volatile 

 matter after equilibrium had presumably been 

 reached, in the samples stored at 90% relative 

 humidity might indicate gradual changes in the 

 affinity of the FPC samples for water or, possibly, . 

 the formation of volatile components other than 

 water. 



Gas chromatographic analyses of the methyl 

 esters of the fatty acids from the Pacific hake 

 FPC show that it was relatively stable under most 

 of the storage conditions described (Table 3). 

 Shono and Toyomizu (1972) suggested that the 

 rate of decrease of C22:6 acid could be used as 

 an indication of oxidative deterioration in fish 

 products. There were no apparent decreases in 

 C22:6 acid content at 50% relative humidity. 

 However, at 90% relative humidity, there were 

 very significant decreases of C22:6 acid content of 



from 8.9 to 26.1% in the temperature range of 

 21° to 43°C. Thus water activity had more effect 

 than temperature on the stability of this FPC 

 preparation. 



Each hake FPC extract described in this paper 

 was separated by silicic acid chromatography into 

 three separate fractions, as previously described 

 (Medwadowski et al., 1971). There were little or 

 no significant changes in the amounts recoverable 

 from each fraction (not shown), and they were not 

 analyzed further. 



In general, these observations confirm the 

 relative stability of FPC during storage, even 

 under adverse conditions of temperature and 

 humidity. 



Acknowledgments 



This investigation was supported in part by 

 contract no. USDC 1-36062 NOAA, U.S. De- 

 partment of Commerce, and in part by a grant 

 from the Tuna Research Foundation, Inc., 

 Terminal Island, Calif. 



Table 2. — Changes in the volatile matter of Pacific hake FPC (78-103) with storage at 

 different temperatures and humidities. 



Storage 



time 

 (month) 



Control 



Average volatile matter (%] 



21-50 



Storage conditions': 

 21-90 32-50 32-90 



43-50 



43-90 





 1 

 3 

 6 

 12 



5.2 

 5.4 

 5.2 

 5.3 

 5.8 



'Hyphens separate degrees Celsius and percent relative humidity. 



846 



