The Studies On The Content Of Arsenic In Vegetable Oilseeds And Oils

In this article, we researched the content of arsenic in oilseeds and oils of the regions ofarsenic contained mineral and other regions in order to analysis the source of arsenic and itsresidues. At the same time, we researched the ways to reduce the arsenic content of rapeseedoils in alkali refining and oil bleaching. The major contents are described as follows:（1）We determined the content of arsenic in oilseeds by pressure digestion combined withHG-AAS. The conditions for pressure digestion were optimized in this research. The resultsshowed that the optimum conditions were as following：sample quantity0.5000g，theresolution temperature160℃, the resolution time5h.When the oilseeds were completelydigested, the solution was very clear.All15determined oilseeds didn’t exceed the nationalstandard. The content of arsenic in oilseeds of the regions of arsenic contained mineral was0.06-0.18mg/kg.The average was0.12mg/kg. The content of arsenic in oilseeds of otherregions was0.04-0.10mg/kg. The average was0.08mg/kg. However, the content of arsenic inoilseeds of regions of arsenic contained mineral were slightly higher than it in other regions.The arsenic content of rapeseed oils was slightly higher than it in the peanuts and sesameseeds.（2）We determined the content of arsenic in oils by solvent extraction combined withHG-AAS. The recoveries were in the range of93.0%-110%.The results showed that all8determined oils didn’t exceed the national standard. The content of arsenic in oils of regions ofarsenic contained mineral was0.028-0.037mg/kg. The average was0.033mg/kg.The contentof arsenic in oils of other regions was0.12-0.030mg/kg. The average was0.020mg/kg.Thecontent of arsenic in oils of regions of arsenic contained mineral were slightly higher than it inother regions. Compared the content of different kinds of oils, the content of rapeseed oilswere slightly higher than it in peanut oil and sesame oil. The content of arsenic oilseeds wasassociated with it in oils.（3）We researched the way to reduce the arsenic content of rapeseed oils in thedeacidification of oils by alkali refining. The optimum conditions of arsenic removal in theprocess of alkali refining were as following：ultra-alkali content0.2%,the alkali concentration12°Bé, the alkali refining temperature75℃, alkali refining time20min. Finally, the arseniccontent of rapeseed oil was0.035mg/kg. And the arsenic removal rate was88%.（4）We researched the way to reduce the arsenic content of rapeseed oils in oil bleaching.The conditions for absorption decolorization of oils were optimized in this research. The results showed that the arsenic removal effect of activated clay was stronger thanattapulgite.And the arsenic removal effect of attapulgite was stronger than NORIT activatedcarbon.And the arsenic removal effect of NORIT activated carbon was stronger than ordinaryactivated carbon. The optimum conditions of arsenic removal in the process of oil bleachingwere as following：activated clay content5%, bleaching temperature110℃, bleaching time20min. Finally, the arsenic content of rapeseed oil was0.040mg/kg. And the arsenic removalrate was73%. The decolorization rate of rapeseed oil was91%. And the process conditionsdid not cause the rise of the trans fatty acids content in rapeseed oil. The conditions for thedeacidification of oils were optimized in this research. The results showed that the content oflead in oil was decreased gradually with the oil refining processing carried out. Arsenicremoval rate is increased. Finally, the arsenic content of rapeseed oil was0.042mg/kg. Andthe arsenic removal rate was88%.The arsenic in the rapeseed oil is mainly removed in theprocess of alkali refining.