| The 3-Chloro-l,2-Propanediol fatty acid esters(3-MCPD esters)and glycidyl esters(GEs)are widely exist in the refined plant oil,which are pollutant and potentially harmful to human body.This problem has become a food safety hotspot issues in recent years.In this paper,soybean oil with lower content and higher content of corn oil were used as raw material,the impacts of oil type,adsorbent type,adsorbent dosage,adsorption temperature and adsorption time on the removal effect of 3-MCPD esters and glycidyl esters in two typical edible oils were investigated.The optimum adsorption conditions of GEs were obtained by orthogonal test.Meanwhile,the formation rules of 3-MCPD esters and GEs of the oil deodorization were studied.On this basis,the temperature and time conditions were optimized by means of two-stage deodorization process,which obtained the optimum adsorption conditions.The main results were as follows:Firstly,soybean oil was used as raw material,the impacts of adsorbent type,adsorbent dosage,adsorption temperature and adsorption time on the removal effect of 3-MCPD esters and glycidyl esters in soybean oil were investigated.The results showed that the removal effect of different adsorbent on 3-MCPD esters from high to low was as follows: H-1activated carbon,activated clay,H-2 activated carbon,common activated carbon,attapulgite.The removal rates of adsorbents were all low.When the dosage of H-1 activated carbon with a relatively better removal effect was 0.5%,the removal rate was merely 34.42%.The order of the removal effect of different adsorbent on glycidyl esters from high to low was as follows: H-1 activated carbon,H-2 activated carbon,common activated carbon,activated clay,attapulgite.The optimal removal conditions were as follows: the dosage of H-1 activated carbon was 3.0%,the adsorption time was 40 min and the adsorption temperature was 100?.Under the conditions,the content of glycidyl esters was reduced from the initial 2.810 mg/kg to 0.124 mg/kg,as the removal rate was 95.59%,which can reach the EU's limit of glycidyl esters in edible oil.Meanwhile,the effect of decolorization is good,the color of soybean oil from the initial Y70R2(133.4 mm)to Y20R3(133.4 mm).Using corn oil as raw material,the impacts of adsorbent type,adsorbent dosage,adsorption temperature and adsorption time on the removal effect of 3-MCPD esters and glycidyl esters in soybean oil were investigated.The results showed that the different adsorbents all cause the increase of 3-MCPD esters,which was not similar to soybean oil.This indicated that different conditions had great influence on the production of 3-MCPD esters and glycidyl esters,such as the different types of oils,the quality of the crude oil,especially the diacylglycerol,monoglyceride,free fatty acid and chloride ion content.The order of the removal effect of different adsorbent on glycidyl esters from high to low was as follows: H-1 activated carbon,common activated carbon,H-2 activated carbon,activated clay,attapulgite.The optimal removeal conditions were as follows: the dosage of H-1 activated carbon was 3.0%,the adsorption time was 40 min and the adsorption temperature was 110?.Under the conditions,the content of glycidyl esters was reduced from the initial 8.56 mg/kg to 0.181 mg/kg,as the removal rate was 97.88%,which can reach the EU's limit of glycidyl esters in edible oil.Meanwhile,the effect of decolorization is good,the color of corn oil from the initial Y30R4(25.4 mm)to Y30R2(133.4 mm).Secondly,the effect of deodorization temperature and deodorization time on the formation of 3-MCPD esters and GEs in oil was studied by using soybean oil and corn oil as raw materials.The results showed that the content of 3-MCPD esters and glycidol esters was increased significantly during the deodorization process.With the higher deodorization temperature and the longer deodorization time,the amount of 3-MCPD esters and glycidol esters had the larger increase.The deodorization temperature had a greater influence on the formation of the two constituents than the deodorization time.When the deodorization temperature does not exceed 230?,the content of 3-MCPD esters and GEs increased slowly,and the content increased rapidly as the temperature continued to rise.With the deodorization temperature wasn't up to 230? and the deodorization time was 60-120 min in soybean oil,the content of 3-MCPD esters was merely increased by 0.053-0.696 mg/kg and the GEs content raised barely by 0.025-5.735 mg/kg.While the deodorization temperature was 250?,even 60 min was applied for the deodorization,the 3-MCPD esters and GEs content were significantly increased by 0.85 mg/kg and 10.006 mg/kg,respectively.Especially in the oil limit deodorization condition of 270? and 120 min,the content of 3-MCPD esters and GEs in soybean oil was up to 2.411 mg/kg and 28.562 mg/kg.For corn oil,with the deodorization temperature wasn't up to 230? and the deodorization time was 60 min-120 min,the content of 3-MCPD esters was merely increased by 0.047-2.581 mg/kg and the GEs content raised barely by 0.3-3.883 mg/kg.While the deodorization temperature was 250?,even 60 min was applied for the deodorization,the 3-MCPD esters and GEs content were significantly increased by 5.039 mg/kg and 8.354 mg/kg,respectively.Especially in the oil limit deodorization condition of 270?and 120 min,the content of 3-MCPD esters and glycidol esters in corn oil was up to 13.004 mg/kg and 34.864 mg/kg.In the same limiting deodorization conditions of 270? and 120 min,the added amount of 3-MCPD esters and GEs in corn oil after deodorization was about 4.6 times and 1.1 times of the increase in the soybean oil,respectively.This showed that there was a significant difference in the formation of 3-MCPD esters in the process of deodorization of two oils.Considering the acid value,the peroxide value and other indicators of two oils and according to the national standard of soybean oil and the new national standard of corn oil,which the do not exceed 230? is recommended for reduce the content of 3-MCPD esters and GEs in oil.When the condition was 230? and 60 min,the acid value and peroxide value of soybean oil was 0.15 and 1.63,respectively.While the acid value and peroxide value of corn oil was 0.32 and 1.24,respectively.When the deodorization time was extended to 120 min,the acid value of deodorized soybean oil and corn oil was 0.08 and 0.20 respectivelyand the peroxide value was 1.35 and 1.72 respectively.All of them can reach the requirement of the standard of soybean oil and new standard of corn oil,namely GB/T 1535-2003 and GB/T 19111-2017,respectively.Thirdly,based on the result of the second,the two-stage deodorization process for controlling and reducing the generation of 3-MCPD esters and GEs was studied by using soybean oil and corn oil as raw materials.The results showed that the two-stage deodorization process had a good control effect on the generation of 3-MCPD esters and GEs in deodorization process.Meanwhile,under the optimum process conditions,the quality indexes of acid value and peroxide value can reach the standard of first-grade product oil.The two-stage deodorization process had a good inhibitory effect on the increase of TFA content in the oil of the deodorization stage and had a good retention effect on the beneficial component in the oil,such as vitamin E and sterol.The optimum two-stage deodorization process conditions of soybean oil were performed as the following conditions.The temperature of the first stage was 180? and kept for 50 min and then heating to 230?,kept for 30 min.Under these conditions,the content of 3-MCPD esters and GEs was increased from 0.276 mg/kg and 1.287 mg/kg to 0.392 mg/kg and 2.52mg/kg,respectively.The adding amount was 0.116 mg/kg and 1.233 mg/kg,respectively,which was significantly lower than the conventional deodorization conditions of higher than 250? and held for 60 min.The added amount of 3-MCPD esters and GEs was up to 0.85mg/kg and 10.006 mg/kg under normal deodorization of 250? and 60 min.Meanwhile,the content of the trans fatty acid content in soybean oil with two-stage deodorization was 0.39%,which was less than the production of conventional deodorized acid in the report,and the content of the report was 1% ~ 4%.What's more,the loss rate of vitamin E and sterol was 10.36% and 10.4% respectively,which were lower than that report of 14%~42%and 13%~27% in the conventional deodorization of soybean oil.The optimum two-stage deodorization process of corn oil was as the following steps.The temperature was firstly heated to 200?and held for 50 min,and then increased to 230? keeping for 30 min.Under the conditions,the content of 3-MCPD esters and GEs was increased from 3.119 mg/kg,2.25 mg/kg to 3.988 mg/kg and 3.027 mg/kg respectively.The adding amount of the content of 3-MCPD esters and GEs was 0.869 mg/kg and 0.777 mg/kg,respectively,which was significantly lower than the conventional deodorization conditions(the incremental of deodorization temperature 250?,time of 60 min are 5.039 mg/kg,8.354 mg/kg.Meanwhile,the trans fatty acid content of soybean oil with two-stage deodorization was 0.31%,VE loss rate was 9.71% and sterol loss rate was 8.29%. |
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