Optimum conditions for preparing acid oil with high EPA and DHA using urea adduction method
1997
Somsamorn Gawborisutti
Soap-stock is a by-product from alkaline refining of tuna oil. It was converted to acid oil by proper conditions in resaponification stage and acidulation stage. At 80 deg C, combining with 35 percent by weight of soap-stock of 50 percent potassium hydroxide and 120 minutes resaponification time are proper conditions in resaponification stage. The saponified soap-stock next was acidulated with concentrated sulfuric acid for 5 minutes, propering time in acidulation stage. After resaponification and acidution amount of EPA and DHA increase about 100 percent of which containing in soap-stock. One part of acid oil, preparing from preliminary stages was added with 3 part of urea then dissolved with ethanol and heat until clear. Urea and urea complex were crystallized 24 hours at -10 deg C to concentrate EPA and DHA. After separate urea complex amout of EPA and DHA in acid oil increase 53 and 56 percent respectively. Concentrated acid oil contrained EPA 52.36 milligram/gram and DHA 240.70 milligram/gram with 35.84 percent yield, total fatty acid 92.72 percent, oxidized fatty acid 6.5 percent, iodine value 56.47, free fatty acid 92.76 and color: brownish yellow.
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