アセトン法とエーテル法の比較
ボーマー数について (第3報)
1965 年 14 巻 6 号 p. 275-278
詳細
1965 年 14 巻 6 号 p. 275-278
Acetone method was compared with ether method in measuring Bömer numbers of pure lard and lard mixtures with beef tallow or horse fat, and was also discussed about its after treatment. In case of ether method, the direct washing of precipitated glyceride by ether was tried as a simlpe and convenient method. In this modified method, 50g of sample fat in a cylinder was agitated with 200ml of ether at 15°C for 1hr, and its precipitate separated was shaken with 50ml of ether at 15°C and was filtered. After that, the precipitate was washed 3 times with each 50ml of ether at 15°C.
1) Both melting points of glyceride (Sg) and fatty acid (Sf) showed higher in the ether method. Consequently, the mean values of Bomer numbers were also higher by 0.25 with abdominal fat and by 0.56 with back fat in the ether method. Precence of another animal fat gave larger difference in the Bomer number than that of pure lard, and the difference of lard mixture containing 20% of beef fat was very remarkable, being 1.12 of its difference. When the content of another animal fat was 40%, the difference came to be smaller, and the same tendency was observed in lard mixtures containing 20% or 40% of horse fat.
2) The crystals of glyceride precipitated from acetone consist of coarse granules while those from ether is extremely fine. In the latter case, the iodine value come to be low since the crystals are washed thoroughly, and the standard deviations (σ) of the measured values are very smaller.
3) Time required for the measurement is far more faster in the ether method, but when a larger amount of glyceride is precipitated, its washing came to be difficult.
4) When recrystallization is repeated in the acetone method, unsaturated glycerides are removed, and the values of (Sg) and (Sf) become higher but the difference of melting point (Sg-Sf) becomes smaller, and the Bomer number come to be low. If recrystallization is repeated twice, the Bomer number becomes slightly higher, but the value is lower than that from ether method. The standard deviations of the measured values come to be very samll by recrystallization.
