Soo-Kyung Moon

Preferential accumulation of fatty acids in the testis and ovary of cultured and wild sweet smelt Plecoglossus altivelis

The effect of dietary lipid on the fatty acid composition of muscle, testis and ovary of cultured sweet smelt, Plecoglossus altivelis, was investigated and compared with that of wild sweet smelt. Cultured fish were fed three different diets for 12 weeks: a control diet rich in docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3) (CO group); a diet deficient in DHA and EPA (DP group); and a diet rich in alpha-linolenic acid (ALA, 18:3n-3), but deficient in DHA and EPA (LP group). The fatty acid composition of muscle and gonad lipids was related with dietary fatty acids. Despite the difference in DHA and EPA content in the diets, muscles and gonads, respectively, contained almost equal levels of DHA and EPA in each CO and DP group. However, the muscle and gonad of the LP group showed a lower level of DHA than other groups, due to having the highest level of ALA. In the wild fish muscle, the DHA content was similar to that of CO and DP groups, but the EPA content showed the highest level in all groups. There was no difference in the muscle fatty acid proportions between male and female. On the other hand, the testes of cultured and wild fish were rich in DHA, EPA, docosapentaenoic acid and arachidonic acid, while ovaries were rich in oleic, palmitoleic, linoleic acids and ALA. Moreover, of all the groups, the fish fatty acid composition of the LP group was closest to that of wild fish. These results indicate that in the sweet smelt, tissue n-3 polyunsaturated fatty acids (PUFAs) greater than C20 can be synthesized from dietary precursors and special fatty acids are preferentially accumulated to the testis or ovary, respectively, to play different physiological functions.

Changes of Nutritional Components in Spanish Mackerel Scomberomorus niphonius by Various Cooking Methods

The changes in the proximate compositions, lipid classes, and fatty acids of muscle and dripped lipids, and the amino acid compositions and mineral content were studied in Spanish mackerel Scomberomorus niphonius muscle cooked using a frying pan, oven, and microwave oven. The moisture content was high in the raw sample (65.7%) and decreased with cooking, decreasing the most with frying pan method (54.5%). Conversely, the protein, lipid and ash contents increased significantly with cooking (P<0.05). The dripped lipid content from the cooked muscles was the highest with the frying pan sample (0.81%) and was approximately half this level in the oven (0.46%) and microwave oven (0.34) samples. The percentage of non-polar lipid (NL) in the total lipid content exceeded 95% for the muscle lipids (13.9-17.6 g/100g sample) and 99% for the dripped lipids (0.34-0.81 g/100 g sample). The prominent fatty acids were 18:1n-9, 16:0, 22:6n-3, 16:1n-7, and 20:5n-3 in the muscle and dripped lipids. The frying pan muscle lipid contained high levels of saturates and monoenes such as 16:0, 18:0, and 18:1n-9, and low levels of polyenes compared with other muscle lipids. The fatty acid compositions of the dripped lipids were similar with all three cooking methods. The prominent total amino acids in Spanish mackerel muscle were glutamic acid, aspartic acid, lysine, leucine, and arginine, and their proportions were similar (45.49-45.82%) in all samples. The potassium and phosphorous contents increased significantly with cooking (P<0.05), and while no heavy metals were detected in any sample. These results indicate that the change in nutritional components, especially the lipid content, was lower with the microwave oven and oven methods compared with the frying pan method.

Proximate and Fatty Acid Compositions of 14 Species of Coastal and Offshore Fishes in Korea

Proximate and fatty acid compositions in muscle tissue were studied in 14 species of coastal and offshore fishes in Korea. Lipid content ranged from 0.57 to 10.5% and was higher in migratory and reef dwelling fishes than in de-mersal fishes. Protein content ranged from 14.4 to 20.3% and moisture content ranged from 72.4 to 81.8% in all fish samples. There was a negative correlation between lipid and moisture content in all fish samples (r= -0.90, P<0.001). The prominent fatty acids were 16:0, 22:6n-3 (docosahexaenoic acid, DHA), 18:1n-9, 20:5n-3 (eicosapentaenoic acid, EPA), 16:1n-7, 18:0 and 18:1n-7. Most demersal fishes contained considerably higher amounts of 20:4n-6 and/or 22:5n-3 compared with migratory and reef dwelling fishes. The proportion of total polyunsaturated fatty acid (PUFA), including DHA and EPA, was higher in demersal fishes (38.6-54.0%) than in migratory and reef dwelling fishes (23.5-35.2%).Key words: Docosahexaenoic acid, Eicosapentaenoic acid, Fish, Lipid, PUFA

Characteristics of Food Nutrition Components of Common Stalked Barnacle Pollicipes mitella

Common stalked barnacle Pollicipes mitella is a filter-feeding crustacean that attaches itself to the surfaces of rocks in the ocean intertidal zone. Pollicipes mitella is one of about a dozen species of goose barnacle that are gathered commercially for human consumption. In Portugal and Spain, they...

Proximate and Fatty Acid Compositions of Commercial Domestic and Imported Melania Snails Semisulscospira sp.

【The proximate, fatty acid and dimethyl acetal (DMA) compositions of domestic and imported melania snails Semisulcospira sp. being sold commercially were studied. The protein content ranged from 8.09% (China) to 11.3% (North Korea). The lipid content ranged from 0.84 (China) to 2.36% (North Korea). Domestic melania snail had protein (10.5%) and lipid (1.02%) contents intermediate between those of the two imported melania snails. The prominent fatty acids were 16:0 and 18:0 saturated fatty acids, 16:1n-7, 20:1n-11, 18:1n-9, 18:1n-7 and 16:1n-9 monounsaturated fatty acids, and 20:4n-6, 20:5n-3 (eicosapentaenoic acid, EPA), 22:2 non-methylene-interrupted diene (NMID), 18:3n-3, 18:2n-6 and 22:5n-3 (docosapentaenoic acid, DPA) polyunsaturated fatty acids (PUFA). The percentage of n-3 PUFA was higher in domestic (19.6%) and North Korean (imported, 19.5%) snails than in that from China (imported, 16.8%), while the n-6 PUFA level was higher in snails from China (21.2%) and domestic snails (14.7%) than in that from North Korea (9.87%). The total DMA, i.e., 18:0 DMA, 16:0 DMA and 18:1 DMA was 7.30, 7.27, and 4.86% domestic snail and those from China and North Korea, respectively. These results suggest that melania snail is a source of n-3 PUFA, and DMA derived from plasmalogen.】

Effects of Eco-friendly Squid Todarodes pacificus Liver and Patagonian Toothfish Dissostichus eleginoides Muscle Oils on the Serum Lipids and Adipose Tissues of Rats

This study investigated the effects of squid Todarodes pacificus liver oil on the serum lipids and adipose tissue weight of rats. The rats in the soybean oil (SO) group received a basic diet prepared according to the recommendations of the American Institute of Nutrition (AIN-93G), with 7% SO as lipid source. The rats in the Patagonian toothfish Dissostichus eleginoides muscle oil (PTFO) group received 5% PTFO and 2% SO as the lipid source, while the rats in the eco-friendly squid liver oil (EFSO) group received 5% EFSO and 2% SO. EFSO was prepared according to the method outlined in the author’s patent. PTFO was extracted from muscle using a physical method in the author’s laboratory. The prominent polyunsaturated fatty acids in the dietary oils were 18:2n-6 (54.3%) and 18:3n-3 (5.64%) in SO, DHA (6.77%) and EPA (3.61%) in PTFO, and DHA (26.2%) and EPA (9.94%) in EFSO. After feeding for 4 weeks, the serum lipid levels (e.g., triglyceride, total cholesterol, and low-density lipoprotein cholesterol) of the rats in the EFSO group were significantly reduced as compared with those in the SO group (P<0.05); those of the rats in the PTFO group were also reduced, albeit not significantly, compared with the SO group. On the other hand, the total white adipose tissue (visceral, epididymal, and perirenal) weight was significantly reduced in the EFSO and PTFO groups compared to the SO group. These results demonstrate that EFSO is an effective lipid modifying agent in rat blood, and that EFSO and PTFO have greater anti-obesity effects than SO.

Changes in Proximate Composition and Lipid Components in Chub Mackerel Scomber japonicus and Japanese Jack Mackerel Trachurus japonicus with Various Cooking Methods

Changes in the proximate composition, lipid classes, and fatty acids were studied in chub mackerel Scomber japonicus and Japanese jack mackerel Trachurus japonicus muscles cooked using a frying pan, oven, and microwave oven. The moisture content was high in the raw samples (chub mackerel 65.5%, Japanese jack mackerel 60.5%) and decreased with cooking, especially in the frying pan method (chub mackerel 49.2%, Japanese jack mackerel 49.8%). In contrast, the protein, lipid and ash contents increased significantly with cooking in chub mackerel muscle (P

Proximate and Fatty Acid Compositions of Three Species of Imported and Domestic Freshwater Fishes

The proximate and fatty acid compositions of the edible portion of three species of cultured freshwater fish (common eel Anguilla japonica, rainbow trout Onchorhynchus mykiss, and Israeli carp Cyprinus carpio) were compared between imports from China and domestically produced specimens. The lipid contents of cultured common eel and rainbow trout were rich in imported fishes (20.4 and 12.2%, respectively) compared with those in domestic ones (16.0 and 8.01%, respectively), while those of Israeli carp were rich only in the domestically produced specimens (8.06 and 3.07%, respectively). There was a negative correlation between the lipid and moisture contents in all fish samples (r