Chemical Changes in the Lipids of frozen Mackerel ordinary Muscle during low Temperature Storage

고등어 보통육의 냉동저장중(冷凍貯藏中) 지질(脂質)의 변화(變化)에 관한 연구(硏究)

A study was made on the changes in Acid Value (AV) and Peroxide Value (POV) of the Mackerel ordinary muscle during low temperature storage. Three different samples were used-natural (control), ascorbic acid (As. A)-added and NaCl-added. The samples were stored at the temperature of $-15^{\circ}C$ during 75days immediately after quick freezing at $-23^{\circ}C$ The change in the amount of fatty acids was also measured by means of GLC method. 1. In comparison with the control, the As. A -added showed lower AV and POV, whereas the Nacl-added gave higher values. 2. Among the various fatty acids, which are constituents of the fish lipids, the amount of palmitic acid (16:0), stearic acid (18:0), and oleic acid (18:1) had been increased during the storage, while there had been steady decrease in the amounts of unsaturated fatty acid such as linolenic acid (18:3), arachidonic acid (20:4), clupanodonic acid (22:5), and docosahexaenoic acid (22:6). 3. For the first 30 days after freezing, the decreasing rates of the amounts of docosahexaenoic acid in three samples of the As. A-added, the control, and the NaCl-added-were 7%, 14% and 36% respectively. However, after 45 days these samples showed the same decreasing rates of more than 57 percent.

고등어 보통육을 ascorbic acid 및 NaCl을 처리하여 냉동저장시 지질의 변화를 산가, 과산화물가 및 지방산조성의 변화 등을 통하여 고찰한 결과는 다음과 같다. 1. 고등어보통육(肉)의 냉동저장기간동안 AV와 POV는 무첨가구에 비하여 As A첨가구는 AV 및 POV가 낮고 NaCl첨가구는 높은 AV 및 POV를 나타내었다. 2. 고등어 육지질(肉脂質)의 지방산조성은 GLC법으로 분석한 결과 $C_{16:0}$산, $C_{18:0}$산, $C_{18:1}$산은 냉동저장기간중 계속 증가되며 $C_{18:3}$산, $C_{20:4}$산, $C_{22:5}$산, $C_{22:6}$산과 같은 불포화도가 높은 지방산은 계속적으로 감소되었다. 3. $C_{22:6}$산의 감소율은 저장초기에는 As A첨가군 : 무첨가군 NaCl첨가군이 1: 2: 3의 비율로 그 감소율이 높았으나, 저장후기에는 유의성이 없었다. 4. 전반적으로 고등어의 냉동저장중 육지질(肉脂質)의 산화 양상에 있어서 무첨가구에 비하여 As A첨가구는 산화를 억제시켰고, NaCl은 산화를 촉진하는 결과를 보였다.