The trans fatty acids in milk fat from the indoor feeding ( March, April) and the pasture feeding period (May) were determined. An argentation thin layer chromatography (Ag-TLC) and gas liquid chromatography (GLC) on a polar capillary column (CP Sil 88) were used.The content of trans fatty acids in milk fat showed considerable seasonal variations. The trans 18:1 content for the pasture period was 5.73 g/100 g milk fat (MF) and only 1.83 g/100 g MF for the indoor feeding period. About one-half of trans 18:1 isomers in the samples from the indoor feeding period and more than 60% in the samples from May was trans-11 18:1 acid. The level of two trans 18:2 isomers (cis-trans and trans-cis) was about 4 times higher (0.81 g/100 g MF) in the pasture feeding period than in the indoor feeding period (0.18 g/100 g MF).
Lipid was extracted from the lipid containing muscle of Liner silver grunter (Pomadasys hasta) by solvent extraction and then purified by standard method. The physico-chemical properties of lipid sample were determined and compared with those of other standard fats and oils. Fatty acid composition of the lipid sample was investigated by Thin Layer Chromatographic (TLC) examination. Gas Liquid Chromatographic (GLC) examination was performed by the methyl esters mixture prepared from the lipid sample. The de-oiled muscle of the fish was studied for the determination of ash content, fiber content, moisture content and protein content. The lipid containing selected muscle was analyzed quantitatively for the determination of percentages of protein, cholesterol and minerals (N, P, K, Ca, and Na). The lipid containing muscle was also analyzed for the determination of the amount of eleven metals by using Atomic Absorption Spectrophotometric method. The lipid sample was evaluated by microbial activity (bacterial activity against nine bacteria and fungal activity against seven fungi).