Research On Determination And Removal Effects Of Zearalenone In Corn Oil

As a kind of common edible vegetable oil in China,corn oil was made from corn germ.Corn oil is rich in unsaturated fatty acids,phytosterols,vitamin E and so on.During its growth and preservation process,corn is easily contaminated by mold which can produce a kind of mycotoxin called zearalenone(ZEN).As a secondary metabolite of fusarium mold,ZEN has the effect of estrogen which can cause serious damage to the reproductive system.It has immune and liver toxicity,strong teratogenic and mutagenic effects,and has the potential carcinogenicity.In addition,it has strong teratogenic and mutagenic effects,and has potential carcinogenicity.The studies on ZEN determination and detoxification in corn and its products have attracted much attention.Corn germ oil,as a corn product,also has the risk of ZEN contamination.Therefore,this paper was focused on the determination and detoxification of ZEN in fats and oils.The main contents are listed as follows.(1)A total of 159 corn oils from China were analyzed.The results showed that ZEN was detected in most of corn oils with an average value of about 170.1 ?g/kg,and ZEN concentrations in a few samples reached 1950 ?g/kg.Furthermore,the changes of ZEN content in each section of refining process were also collected and analyzed.The content of ZEN in each corn oil sample decreased obviously after alkali refining,which was about 8.0%~65.5%.As to bleaching,dewaxing and deodorizing process of refining corn oil,ZEN concentrations of the samples from a few plants increased while others decreased.(2)The pretreatment process of the existing high performance liquid chromatography(HPLC)quantitative determination method for ZEN was improved.The existing international standard determination method adopts immunoaffinity column pretreatment,which has high cost and tedious operation.In this study,ultrasound assisted solvent extraction took the place of the conventional immunoaffinity column pretreatment.Taking the extraction recovery of ZEN as the index,the pretreatment conditions of ultrasonic solvent extraction were optimized.The optimized conditions were obtained as the mixture solvents of acetonitrile/water(9:1,V/V),solid-liquid ratio of 1:4(m/V,g/ml),ultrasonic extraction time of 20 min.These extraction conditions could achieve the effective isolation and accurate quantification of ZEN in subsequent HPLC determination,and the determination limit could reach 4.5 ?g/kg.The recoveries and method repeatabilities were good under different spiked levels.The spiked recoveries with 10 ?g/m L,100 ?g/m L and 1000 ?g/mL were 77.9%,105.7% and 95.0%,respectively.The relative standard deviations were 2.05%~8.43%.Specially,the results of 1000 ?g/mL spiked sample showed that this method was better than the traditional immunoaffinity column pretreatment method.(3)The removal efficiencies of ZEN from corn oil by alkali refining and UV irradiation were evaluated.Single factor experiment was conducted on the corn oil samples with ZEN content of 7488.67 ?g/kg in order to optimize the processing conditions for ZEN removal by alkali refining.The optimized conditions were obtained as extra alkali content of 0.2%,alkali refining time of 20 min,alkali refining temperature of 55°C,stirring speed of 500 rpm/min.The effects of this method on the removal rates of ZEN in different concentrations under these conditions were evaluated.The final ZEN contents of corn oils with 725.4 ?g/kg and 7488.67 ?g/kg after alkali refining were decreased to 51.1 ?g/kg and 2463.22 ?g/kg,respectively.When the ZEN content was low,the sample could meet the EU regulations(400 ?g/kg)after removal;When the ZEN content was high,the sample needs to be further carried out the second alkali refining.However,the effect of UV irradiation on the removal of ZEN was not ideal.For the mixture solution of methanol/water(1:1)with ZEN standard of 5000 ?g/kg,the removal rate could reach 55.79% under the optimized absorption wavelength of 235 nm and 5 h irradiation,whereas it was only 6.37% under 270 nm.However,the removal efficiencies of 235 nm and 270 nm irradiation were poor for the ZEN in corn oil.The removal rate of 235 nm and 270 nm irradiation with 5 h were 1.52%~6.32% and 3.29%~4.86%,respectively.