Study On Color Displaying Detection Of Sesame Oil Adulterated With Soybean Oil

Sesame oil received deeply popular by people for its unique flavor and taste. Due to itsnutritional value and marketable value are higher than that of soybean oil, rapeseed oil,cottonseed oil and so on, and no purity request was limited in the national standards, whichcause above70%sesame oil is adulterated in present market. The adulteration of sesame oilnot only causes the losses to the legitimate operator and the general consumer, but also posesa potential threaten to human health. However，the current detection methods of adulteratedsesame oil cannot meet the requirements of contemporary laws and regulations. It is difficultto distinguish the adulteration or not with conventional physical and chemical detectionmethods. In addition, modern detection methods present some other problems, such as morecomplex operations, the high cost, and the less universal in our country. Therefore, it isnecessary to develop a convenient, rapid, and accurate detection method of sesame oil forqualitative and quantitative of sesame oil.In this paper, qualitative and quantitative detection of adulterated sesame oil were takenas main objects. In order to build specificity, accuracy, and feasibility method for quantitativedetection, the Villavecchia, Boudouin and chloroform-concentrated sulfuric acid method werepreliminary studied for choosing one stable reaction system method. Afterward the sesame oilblended with different proportion first-level soybean oil were detected as research objects forconfirming a rapid, convenient development process, which not only can distinguish thesesame oil sample through the visual detection, but also can estimate the adulteration ratio.The main contents and specific conclusions of this paper were as follows:1) Based on preliminary study of the existing three colored methods, Villavecchia wasselected as the basis for quantitative detection. The method was as below: the sesame oil wasmixed with concentrated hydrochloric acid for30s, followed by standing for10min, adding3mL water and shaking immediately, and then absorbance values at415nm and520nm weredetected. The standard curve linear range is from0to0.024g, and the recovery rate was up to95.67%~102.79%. In practical test, the dual-wavelength detection further enhanced theaccuracy of test results. When the determination results of dual-wavelength are both higherthan95%, the sample can be considered as pure sesame oil;2）Trichloroacetic acid method and its optimized method were studied, which candistinguish the sesame oil sample and estimate the blended proportion just by the visual detection. The method is following:0.500g sesame oil samples was added to0.5mLpetroleum ether, added into3mL40%trichloroacetic acid solution,0.5mL2%peroxyaceticacid solution, and then added the petroleum ether till5mL volume, after15min, the apparentdifferent color were observed. The above5%blended proportion can be identified. When theamount of adulteration was less than30%in sesame oils, the absorption peak appeared ataround630nm in the visible absorption spectral scanning and the absorbance value reduceswhile the amount of adulteration increases.