The pigment components in edible vegetable oil are complex, mainly including chlorophyll, carotene, flavone pigment, anthocyanin, and the decomposition products of some sugars and proteins.
Some Decoloration method of edible oil
The pigment components in edible vegetable oil are complex, mainly including chlorophyll, carotene, flavone pigment,anthocyanin, and the decomposition products of some sugars and proteins. In addition, cottonseed oil contains brownish red gossypol, which is a toxic component. As most of the pigment components have strong stability, it needs to be treated by decolorization process. The color index of edible oil is one of the characteristic indexes to evaluate the quality of edible oil, especially for the oil used in edible, cosmetic and fine chemical fields, the requirements for its color are more strict. The pigment in edible oil will affect the appearance and performance of the oil. Different pigments have different effects on the stability of the oil. Therefore, in the process of edible oil processing, edible oil should be decolorized to change the color of edible oil; The purpose of making edible oil meet the requirements of different product grades.
Decolorization method of edible oil:
1. Adsorption decolorization
2. Decolorization by heating
3. Oxidative decoloration
4. Chemical reagent decolorization
Adsorption decolorization is commonly used in the decolorization of edible oil. The principle of adsorption decolorization method is to use the characteristic that the adsorbent with strong adsorption force can adsorb pigments and other impurities in hot oil, and remove the adsorbed pigments and impurities while filtering the adsorbent, so as to achieve the purpose of decolorization and purification of edible oil.
General conditions for edible oil decolorization (adsorption decolorization):
1. Requirements for adsorbent
The adsorbent shall have strong adsorption capacity, good selectivity, low oil absorption rate, no chemical reaction with polonium, no special smell and taste, low price and abundant sources. Activated clay is a widely used adsorbent.
2. Decolorization temperature
Low temperature is favorable for surface adsorption; When the temperature is high, chemical adsorption can be carried out, but it is easy to decompose the soap to produce fatty acids. Therefore, the high decoloration temperature is generally 104-110 ℃ under normal pressure and 82 ℃ under vacuum.
3. Decolorization time
Intermittent operation for 15-30min and continuous decoloration for 5-10min.
4. Oil moisture content
When the moisture content of oil is below 0.2%, it will affect the adsorption of clay when it reaches 0.3%. The phosphorus content is less than 10-30mg / kg.
5. Amount of clay
To the extent that the specified decolorization effect is achieved.