The refining degree of tertiary oil and quaternary oil is low, and only through simple degumming and deacidification procedures. Its color is dark, smoke point is low, cooking fume is large, and soybean oil even has soybean smell. Due to the low degree of refining, the impurities in the third and fourth grade edible oils are high, but at the same time, some carotene, chlorophyll, vitamin E and so on are retained.
Rapeseed oil is divided into many grades, and the high-grade rapeseed oil is more refined and has higher nutritional value. However, most enterprises can't reach the first-class standard when refining rapeseed oil, so the most common rapeseed oil on the market should be third-class or fourth-class rapeseed oil, but there is little difference between them. Because rapeseed oil lacks essential fatty acids such as linoleic acid, its fatty acid composition is unbalanced, and its nutritional value is lower than that of ordinary vegetable oil.
Extended data:
National quality standard of rapeseed oil: The national quality standard of rapeseed oil was issued by the government on August 3, 2004.
The refractive index of low erucic rapeseed oil is n1.4651.4691.467 relative density d202000 0.95438+000.92000 0.9140.920 iodine value gi.
Fatty acid composition% 14 fatty acid with carbon below ND myristic acid C 14:0 ND0.2 ND0.2 palmitic acid c16: 01.56.02.57.0 palmitoleic acid c16:1.
Stearic acid C 17:0 ND0. 1 ND0.3 heptadecenoic acid c17:1nd0.3 stearic acid c18: 00.53.10.
Linoleic acid c18: 2110.023.0/5.030.0 linolenic acid c18: 35.013.05.010.
Arachidonic acid C20:2 ND 1.0 ND0. 1 docosanoic acid C22:0 ND2.0 ND0.6 erucic acid C22: 1 3.060.0 ND3.0 docosahexaenoic acid C22:2 ND2.0 ND0. 1.
Wood tar acid C24:0 ND2.0 ND0.3 tetracosenoic acid C24: 1 ND3.0 ND0.4
Baidu Encyclopedia-National Quality Standard for Rapeseed Oil