No abstract

The fatty acid composition of iced, frozen and frozen-glazed brown shrimp (Penaeus aztecus) was determined as a function of storage time. The iced shrimp were analyzed every third day for 18 days while both frozen sets were analyzed at regular intervals for 183 days. No significant changes in neither the iced, frozen nor the frozen-glazed shrimp could be detected.

An icosatetraenoic fatty acid, though to be allcis‐5,8,11,14‐icosatetraenoic acid (arachidonic acid), was isolated from shrimp total lipid. The acid was subjected to partial reduction with hydrazine hydrate, with subsequent isolation of the monoenoic reaction products which were shown to becis in structure. These were then cleaved by periodate‐permanganate oxidation and the resulting mono‐and dicarboxylic acid were converted to methyl esters. Identification of the resulting mono‐ and dicarboxylic acids indicated that the original icosatetraenoic acid had the allcis‐5,8,11,14 pattern of double bonds, and it was thus identified as arachidonic acid. Experiments were also performed to study the synthesis of arachidonic acid 20∶4(5,8,11,14) from linoleic acid, 18∶2(9,12) in microsomes prepared from shrimp hepatopancreas and tail muscle tissue. Each step of the pathway 18∶2(9,12)→18∶3(6,9,12)→20∶3(8,11,14)→20∶4(5,8,11, 14) was assayed separately, and the level of activity of each enzyme was expressed as percentage conversion of substrate to product. It was found that, in each step of the sequence, the enzyme activity in the shrimp tissue was very low compared to the activity found in rats. These and previous observations seem to indicate that the arachidonic acid in shrimp tissue originates mostly in the diet.