No abstract

The changes in lipid characteristics of mullet Mugil cephalus roe during processing to Karasumi product were investigated. The Karasumi was prepared according to the conventional process of salting, desalting, and sundrying. The unprocessed roe contained wax esters (WE), triacylglycerols (TAG), free fatty acids (FFA), and phosphatidylcholines (PC) as major lipids, which accounted for 69.2, 13.2, 4.0, and 5.6 of total lipids, respectively. WE contained saturated fatty alcohols and monoenoic and polyenoic fatty acids as main components, whereas saturated fatty acids and monoenoic fatty acids were dominant in TAG. The WE level and its fatty alcohol composition and fatty acid composition did not show signiˆcant changes during the whole process. The level of TAG showed a slight decrease during the sun-drying process, while no changes were observed in its fatty acid composition. The FFA level, especially the free-total saturated fatty acids level, increased during the whole process, indicating that FFA were mainly supplied from degradation of TAG during the processing. There were no statistical changes in PC level or its fatty acid composition. These results suggest that the lipid proˆles of mullet roe remain unchanged during processing to Karasumi product, compared with other dried seafood products.

No abstract

The lipid and fatty acid compositions in the various organs (muscle, liver, other viscera) and stomach contents of three common herbivorous fish species in Japan, Siganus fuscescens, Calotomus japonicus and Kyphosus bigibbus, were examined to explore the stable 20:4n-6 (arachidonic acid, ARA) sources. Triacylglycerol (TAG), phosphatidylethanolamine (PtdEtn), and phosphatidylcholine (PtdCho) were the dominant lipid classes, while the major FA contents were 16:0, 18:1n-9, 16:1n-7, 14:0, 18:0, 18:1n-7, and some PUFA, including ARA, 20:5n-3 (eicosapentaenoic acid, EPA), 22:5n-3 (docosapentaenoic acid, DPA), and 22:6n-3 (docosahexaenoic acid, DHA). The amounts of these fatty acids were varied among species and their lipid classes. Phospholipids contained higher levels of PUFA than TAG. However, ARA in both phospholipids and TAG was markedly present in the muscle and viscera of all specimens, particularly in C. japonicus and K. bigibbus. Moreover, their ARA levels were higher than the levels of DHA and EPA. The observed high ARA level is unusual in marine fish and might be characteristic of herbivorous fish. Furthermore, ARA was the dominant PUFA in the stomach contents of the three species, suggesting that the high ARA level originated from their food sources. The above indicates that these three herbivorous fishes are ARA-rich marine foods and have potential utilization as stable ARA resources.

The physicochemical properties of recovered protein from Japanese anchovy using salt water treatment and pH-shift processing were investigated and compared. The protein recovery yield was the highest with the acid-aided treatment, followed by the salt water and alkaline-aided treatments. No significant differences were found between minced fish and the recovered protein using salt water treatment in L* value, b* value and Ca-ATPase activity. Moreover, myofibrillar protein extracted from the recovered protein using salt water and acid-aided treatments exhibited lower surface hydrophobicity than that using the alkaline-aided treatment. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis indicated a greater concentration of myosin heavy chain and actin in the recovered protein by the salt water treatment, while those proteins were degraded in the acid and alkaline-aided treatments. Overall, the results demonstrated that the physicochemical properties of the recovered protein using salt water treatment were superior to those using pH-shift processing.