Control And Removal Of 3-chloropropanol Ester And Glycidyl Ester During The Refining Process Of Rice Bran Oil

The annual output of rice in China exceeds 200 million tons,accounting for about 32.24% of the total grain output.Rice bran is a by-product of rice processing,with an annual output of about 15 million tons.The fatty acid composition of rice bran oil extracted from rice bran is reasonable and rich in various nutrients such as oryzanol,vitamin E,and phytosterols.It is an internationally recognized healthy fat.However,the lipase content in rice bran is high,and the activity of lipase is high.The acid value of rice bran oil is very high and the color is difficult to remove.Rice bran oil contains more 3-chloropropanol esters and glycidyl esters.Therefore,3-chloropropanol esters and glycidyl esters need to be controlled and removed during the processing of rice bran oil.The existing research results show that chloride ions,monoglycerides and diglycerides in oils and fats are the main precursors for the formation of 3-chloropropanol esters and glycidyl esters in the deodorization of oils and fats.This subject mainly controls the formation of 3-chloropropanol esters and glycidyl esters during the deodorization of rice bran oil by reducing the content of monoglycerides and diglycerides in the deodorized oil of rice bran belt.Collect rice bran crude oil samples from rice bran oil processing enterprises,detect their acid value and glyceride composition and 3-chloropropanol ester and glycidyl ester content,analyze and study the relationship between crude oil acid value and glyceride composition and nutrient content;The effects of the alkali refining deacidification process on the composition of rice bran oil glyceride and the content of 3-chloropropanol and glycidyl ester were analyzed.The results show: The content of monoglycerides and diglycerides in rice bran crude oil increased significantly with the increase of the crude oil acid value;The 3-MCPD ester and GEs contents did not show a clear correlation with the crude oil acid value.After deacidification by alkali refining,both rice bran oils have significant deacidification effects,but the reduction in the content of monoglyceride and diglyceride is limited.The contents of 3-MCPD ester and GEs both decreased significantly during the deacidification process of alkali refining.This may be due to the adsorption and removal of soap feet during alkali refining or the elution of water after alkali refining.In addition,the deacidification of alkaline refining caused the loss of oryzanol?VE?sterol in rice bran oil.In this project,rice bran oil was deacidified by distillation.The removal rate of monoglyceride and diglyceride was used as an index for investigation.At the same time,the control of 3-chloropropanol ester and glycidyl ester was taken into consideration to optimize the conditions of distillation deacidification.In this project,rice bran oil was deacidified by distillation.The removal rate of monoglyceride and diglyceride was used as an index for investigation.At the same time,the control of 3-chloropropanol ester and glycidyl ester was taken into consideration to optimize the conditions of distillation deacidification.The results show: The best distillation conditions are distillation temperature 230 ? and distillation time 100 min.Under this condition,the removal rate of monoglyceride and glycolide in rice bran oil is higher than that of alkaline refining.But the effect of distillation deacidification is obviously not as good as alkali deacidification.At the same time,alkali deacidification can reduce 3-MCPD esters and GEs.Deodorize two kinds of rice bran deacidified oil.The effects of glyceride composition,3-MCPD ester and GEs content of deodorized rice bran oil on 3-MCPD ester,GEs and comprehensive quality in deodorized rice bran oil were analyzed and studied.The results show: It can be seen from the comparison that the alkali deacidification is better than distillation deacidification.This is because the deacidification by distillation has a good effect on the removal of monoglycerides and diglycerides,but,the high temperature in the distillation process and the higher content of monoglyceride and diglyceride in the distilled rice bran oil itself cause the formation of more 3-MCPD esters and GEs in the distillation process.The high content of 3-MCPD ester and GEs in the rice bran oil to be deodorized provides a bad basic condition for the high content of 3-MCPD ester and GEs in the deodorized rice bran oil,making the content of the two components in the deodorized oil still very high.In addition,The retention rate of nutrients in distillation,deacidification and deodorization has advantages and disadvantages in alkaline deacidification and deodorization.This topic considers to ombine the two deacidification methods.Firstly,the acid value of rice bran oil is reduced by alkali deacidification,and then the acid value is further reduced by distillation deacidification,and at the same time,the monoglycerides and the diglycerides are removed,and finally the deodorization treatment is carried out for 50 minutes to obtain finished oil.According to the different of distillation deacidification,it is divided into 4 groups of refining processes,and then 3 different types of rice bran oil samples are subjected to the above refining treatment.The results show: After alkali deacidification and distillation deacidification,the acid value of three kinds of rice bran oil is reduced to the national standard requirements under four conditions.After deodorization,the growth rates of 3-chloropropanol esters and glycidyl esters in each rice bran deodorization oil are lower than that of a single deacidification refining method.And the growth rate of the two increases with the temperature of distillation deacidification;Therefore,the best refining condition is No.1 refining process;In addition,the content of 3-chloropropanol ester and glycidyl ester in No.1 rice bran crude oil are close to the EU's unrefined oil limits.After refining through the best process,the contents of 3-chloropropanol esters and glycidyl esters are 2.16mg/kg and 0.85mg/kg,respectively,which conform to the EU's limit standards for refined vegetable oil(2.5mg/kg,1mg/kg).It can be seen from this that the selection of the best refining process can make the rice bran crude oil with lower contents of 3-chloropropanol esters and glycidyl esters meet the limit of the corresponding refined vegetable oil after refined.In addition,The loss of nutrients is at a normal level.This topic considers selecting molecular distillation for deacidification and analyzing its effect on 3-chloropropanol esters and glycidyl esters.The results show: The best molecular distillation conditions are distillation temperature 230 ?,feed rate 60d/min,scraping film speed 220r/min;The removal rates of monoglycerides and diglycerides of the two rice bran oils are higher than those of steam distillation deacidification,and 3-chloropropanol esters and glycidyl esters are greatly reduced;Molecular distillation will cause a large loss of nutrients.Deodorize the bleached oil and the oil to be deodorized after molecular distillation,It can be seen that after removing a large amount of monoglycerides and diglycerides by molecular distillation,the contents of 3-chloropropanol ester and glycidyl ester in rice bran oil No.1 were 0.55mg/kg and 0.11mg/kg;The contents of No.2 rice bran oil was 1.80mg/kg and 0.95mg/kg;Therefore,it can be explained that after deodorization by molecular distillation,the content of 3-chloropropanol ester and glycidyl ester of the two rice bran oils is lower than the EU limit,and the generation rate is far lower than that of the rice bran oil directly deodorized.