Detection of Corn Oil in Adulterated Sesame Oil by Chromatography and Carbon Isotope Analysis

Abstract

AbstractsThis study was performed to the development of methods for the identification and detection of corn oil in adulterated sesame oil. The fatty acids composition and carbon isotope ratio of authentic sesame oil and adulterated sesame oil with corn oil were studied by using GC‐FID and IRMS. The content of palmitic (P), linoleic (L), and linolenic (Ln) acids increased gradually as the mixed rate of corn oil was increased, whereas the content of stearic (S) and oleic (O) acids decreased. On increasing the mixing ratio of corn oil, the stearic acid contents and the (L × L)/O ratio showed significant differences between authentic and adulterated sesame oils (p < 0.05). The δ13C‰ value for authentic sesame oil and corn oil fell into the range of −27.68 to −29.26‰ and −16.51 to −17.27‰. The adulterant had more carbon‐13 compared with those of authentic sesame oil and the δ13C‰ value was increased linearly (r2 = 0.996). Therefore, the combination of the stearic acid% (<4.8%), (L × L)/O ratio (>56.1) and the carbon isotope ratio (> −27.0‰) turned out to be a good tool for detecting the adulteration of sesame oil with the cheaper corn oil, up to the 10% level.

Differentiation of Lard, Chicken Fat, Beef Fat and Mutton Fat by GCMS and EA-IRMS Techniques

“…Many past reports highlighted the use of stable isotope ratio in the detection of adulteration in edible oils. For instance, the potential use of SIRMS has been investigated for detection of sesame oil adulteration with corn oil 15 , adulteration of ganoderma spore lipid with cheaper vegetable oils 16 as well as adulteration of maize oil with other vegetable oils 17 . According to our literature search, the carbon isotope ratios determination has been scantily used for differentiation of animal fats such as lard, chicken fat, mutton fat and beef fat.…”

Application of Chromatographic and Infra-Red Spectroscopic Techniques for Detection of Adulteration in Food Lipids: A Review

“…Interestingly, this approach enabled the detection of contamination of olive oil with sunflower oil at the lowest of 1% level. Similarly, Seo and co-workers [29] suggested to the use of stearic acid content in combination with the ratio between linoleic and oleic acid to detect sesame oil adulteration by corn oil. This method, however, could detect sesame oil adulteration only above 5% level.…”

Determination of 2-Propenal Using Headspace Solid-Phase Microextraction Coupled to Gas Chromatography–Time-of-Flight Mass Spectrometry as a Marker for Authentication of Unrefined Sesame Oil

“…Therefore, the economically motivated adulteration of sesame oil, with potential impact on the oil quality, nutritional value, and safety to consumers, is a critical problem. Adulterated sesame oils are most commonly manufactured by blending pure unrefined sesame oil with cheaper and lower quality edible oils such as refined corn and soybean oils [4,5].…”

“…For instance, several nonseparation/nondestructive techniques (e.g., isotope ratio mass spectrometry, infrared spectroscopy, and nuclear magnetic resonance spectroscopy) have been applied for the detection of adulterated sesame oils [1,4,6]. Previous studies have also employed techniques such as gas chromatography (GC) coupled with a flame ionization detector [7] or mass spectrometer [8,9], high performance liquid chromatography with a refractive index detector [10], an evaporative light scattering detector [5,11] or a fluorescence detector [12], an electronic nose [13], and realtime PCR [14].…”

“…Despite the recent advances in the analytical 2 Journal of Chemistry methods available for the detection of sesame oil adulteration, the minimum adulteration detection levels remain relatively high. Currently, it is possible to detect the presence of refined corn oil in unrefined sesame oil at ≥10% [1,4] and that of refined soybean oil at ≥3% [1]. This limitation arises mainly from the fact that sesame oil and oil adulterants (e.g., corn and soybean oils) have very similar physical, chemical, and biological properties.…”