Abstract
Differences in lipid composition including fatty acid, lipid class, sterol and especially carotenoid between fleshes of wild and cultured prawn, Penaeus japonicus, were studied. Total lipids were extracted from the flesh during the spawning period and fractionated into two lipid classes of polar and nonpolar lipids by silicic acid column chromatography. The fatty acid composition of each lipid classes, total lipid (TL), nonpolar lipid (NL) and polar lipid (PL) were analyzed by gas liquid chromatography. The sterol and carotenoid composition of total lipids were determined by using thin layer chromatography, gas liquid chromatography and column chromatography using MgO-celite 545 and silicic acid-celite 545 as an absorbent, and by UV spectrophotometry. Total lipid contents of both fleshes from the wild and cultured prawn were about $2.0\%$ on average, but the content of the unsaponifiable matters in the cultured prawn (about $16.2\%$ in total lipid) showed a little higher than that of the wild prawn (about $13.9\%$ in total lipid) and the ratio of NL to PL in total lipid was 1:1.7. In the fatty acid composition of TL, the contents of $Cl_{16:0}\;and\;C_{20:3}$ fatty acids were higher in wild prawn than in cultured prawn, while the contents of $Cl_{18:1}\;and\;C_{20:5}$ fatty acids in cultured prawn were higher than those in wild prawn. The cultured prawn contained higher amounts of monoenoic acids and lower amounts of polyenoic acids than the wild prawn. In the fatty acid composition of NL, the wild prawn showed higher levels in $Cl_{18:0}\;and\;C_{20:1}$ fatty acid contents than the cultured prawn, while the cultured prawn contained much amout of $Cl_{16:0}\;and\;C_{18:1}$ fatty acids. On the other hand, the fatty acid composition of PL showed that $Cl_{16:1}\;and\;C_{17:1}$ fatty acid were higher in the wild prawn than in the cultured prawn, but in $Cl_{16:0}\;and\;C_{18:1}$ fatty acids, the levels were reversed. Consequently, the cultured prawn contained higher amount of monoenoic acids, and similar amounts of saturated acids and polyenoic acids to the wild prawn in NL. And the cultured prawn contained lower amount of monoenoic acids, and similar amounts of saturated acids and polyenoic acids to the wild prawn in PL. In sterol composition of both the wild and cultured prawn, the predominant sterol was cholesterol with the proportion of $78.7{\sim}88.9\%$ to the total sterol. In addition to the cholesterol, the other minor sterols such as 24-methylene cholesterol and sitosterol were detected. Total carotenoid content in flesh of the wild prawn was relatively higher than that of the cultured prawn marking 70 mg/100g of lipid in wild prawn and 40 mg/100 g of lipid in cultured prawn, respectively. The main carotenoids of the both prawns were astaxanthin($54.1{\sim}60.8%$), phoenicoxanthin ($16.5{sim}22.9%$),${\bata}-carotene\;(20.0{\sim}22.0%)$.
천연 및 양식산 보리새우의 지질성분을 비교하기 위하여, 주산란기를 전후하여 채취한 각 시료에서 총지질을 추출하였고, 이를 TLC, GLC 및 column chromatography를 이용하여 총지질의 지방산조성, sterol조성 그리고 비극성지질과 극성지질의 지방산 조성을 측정하였다. 그리고 UV spectrophotometer, 기타 물리화학적 시험으로 천연 및 양식산 보리새우 근육의 carotenoid조성을 정양하여 다음과 같은 결론을 얻었다. 1 보리새우 근육의 총지질함량은 평균 $2.0\%$로서 천연 및 양식산 보리새우의 지질함양 차이는 없었다. 그러나 불검화물양은 총지질에 대하여 천연산이 평균 $13.9\%$, 양식산이 평균 $16.2\%$로서 양식산보리새우가 천연산 보다 약간 높은 함양치를 보였다. 그리고 총지질에 대한 NL과 PL의 함양비율은 평균 1:1.7로서 PL의 함양이 높았다. 2. TL의 지방산조성에서, 천연산은 $C_{18:0}$ 및 $C_{20:3}$산의 조성비가 높았고, 양식산은 $C_{18:1}$ 및 $C_{20:5}$산의 조성비가 높게 나타났으며, 양식산은 천연산에 비하여 monoene산의 함양이 높고 polyene산의 함양치가 낮았다. 3. NL의 지방산조성에서, 천연산은 $C_{18:0}$ 및 $C_{20:1}$산의 조성비가 높았고, 양식산은 $C_{16:0}$ 및 $C_{18:1}$산의 조성비가 높게 나타났으며, 양식산은 천연산에 비하여 monoene산의 함양이 높고 그 밖에 포화산 및 polyene산의 함양은 비슷하였다. 4. PL의 지방산조성에서, 천연산은 $C_{16:1}$ 및 $C_{17:1}$산의 조성비가 높았고, 양식산은 $C_{16:0}$ 및 $C_{18:1}$산의 조성비가 높게 나타났으며, 양식산은 천연산에 비하여 monoene 산의 함양이 낮고 그 밖에 포화산 및 polyene산의 함양은 비슷 하였다. 5. 천연 및 양식산 보리새우의 sterol은 cholesterol이 $78.7{\sim}88.9\%$의 함양분포를 보여 주성분을 이루고 그 밖에 24-methylene cholesterol, sitosterol등이 소량성분으로 검출되였다. 특히 24-methylene cholesterol은 양식산에서 다소 높게 나타난 반면, 천연산에서는 거의 나타나지 않거나 극소량이 존재하여 천연 및 양식산 보리새우의 sterol조성의 차이를 보였다. 6. 양식산 보리새우근육의 총 carotenoid 함량(평균 40.7 mg/100g of lipid)은 천연산(평균 70.4 mg/100 g of lipid)에 비하여 현저히 낮았고, 보리새우 근육의 carotenoid는 astaxanthine ($54.1{\sim}60.8%$)이 주성분이고 그 밖에 phoenicoxanthin($16.5{sim}22.9%$), ${\bata}-carotene\;(20.0{\sim}22.0%)$이 주체를 이루고 있었다.