Authenticity Of Edible Oils Research Articles

Rapid screening of mixed edible oils and gutter oils by matrix-assisted laser desorption/ionization mass spectrometry

Authentication of edible oils is a long-term issue in food safety, and becomes particularly important with the emergence and wide spread of gutter oils in recent years. Due to the very high analytical demand and diversity of gutter oils, a high throughput analytical method and a versatile strategy for authentication of mixed edible oils and gutter oils are highly desirable. In this study, an improved matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) method has been developed for direct analysis of edible oils. This method involved on-target sample loading, automatic data acquisition and simple data processing. MALDI-MS spectra with high quality and high reproducibility have been obtained using this method, and a preliminary spectral database of edible oils has been set up. The authenticity of an edible oil sample can be determined by comparing its MALDI-MS spectrum and principal component analysis (PCA) results with those of its labeled oil in the database. This method is simple and the whole process only takes several minutes for analysis of one oil sample. We demonstrated that the method was sensitive to change in oil compositions and can be used for measuring compositions of mixed oils. The capability of the method for determining mislabeling enables it for rapid screening of gutter oils since fraudulent mislabeling is a common feature of gutter oils.

Characterization of diacylglycerol isomers in edible oils using gas chromatography–ion trap electron ionization mass spectrometry

Verifying the authenticity of edible oils is of international concern. A new quality control standard for olive oil has been proposed that relates the ratio of 1,2-diacylglycerol (DAG) to 1,3-DAG to sensory aspects of olive oil. DAGs and their isomers are difficult to quantitate and characterize by Flame Ionization Gas Chromatography (GC-FID) due to the lack of suitable standards. Mass detectors offer the advantage of providing structural detail to the eluding DAG(s), thus removing ambiguity to the identification of both resolved and unresolved DAGs in GC chromatograms. In this study, a GC Electron Ionization Mass Spectrometry (GC-EI-MS) method was developed to determine the fatty acid composition and molecular structure of trimethylsilyl (TMS) derivatized DAGs present in edible oils. Twenty-two species of DAG isomers were identified in refined coconut oil and unrefined olive oil utilizing signature fragment ions, [M−15]+, [M−89]+, [M−RCO2]+, [RCO2+58]+ and [M−RCO2CH2]+. The [M−RCO2CH2]+ ion is considered the key diagnostic ion to distinguish between DAG positional isomers. MS/MS spectra of [M−RCO2]+ and [M−15]+ ions obtained from commercial standards containing both 1,2- and 1,3-DAG isomers were used as a model system to confirm the identification of DAG isomers in natural products. Furthermore, a number of reaction mechanisms are proposed to explain the formation of the most abundant mass fragments of DAGs and their isomers.

Development and optimization of an efficient method to detect the authenticity of edible oils

The authenticity of edible oils has recently attracted increased attention, particularly due to the emergence of swill-cooked dirty oil. There has not been an effective method to detect the authenticity of edible oils due to the diversity of edible oils, the trace DNA in oils and serious DNA degradation. In this study, an efficient method was developed and optimized to detect the authenticity of edible oils. The stability and efficiency of detecting the authenticity of edible oils were dramatically increased by the DNA extraction method, amplification fragment selection and nano-real time PCR. The DNA extraction method was optimized with regard to the type and the amount of organic reagent, the types and the amounts of extraction buffer, and the DNA carriers. The types of organic reagents and DNA carriers determined whether DNA could be successfully extracted from different edible oils. The amount of DNA extracted from edible oils and adulterated edible oils with the optimized extraction method was evaluated by real-time PCR with different amplification fragments and nano-real time PCR. The results showed that 10 mL soybean oil can be detected against a background of 40 mL sesame oil. Additionally, the new nano real-time PCR technology was applied to amplify the DNA in edible oils at the first time. The efficiency and the precision of the PCR were dramatically increased by gold colloid. The results from this research are beneficial for detecting the authenticity of edible oils.

Calorimetry for Fast Authentication of Edible Oils

There are little data in the literature on how to authenticate edible oils through calorimetry techniques. However, oil melting curves can be used to represent correlations between calorimetric results and oil quality. A calorimetric method has been developed for studying the solid–liquid phase transitions of olive oil and seed oils, in which melting peak behavior is correlated to the type, quality, and composition of the oil. Good reproducible thermograms were obtained by defining precise protocols for use in testing, which take into account the specific characteristics of a particular oil. This approach does not replace classical analytical methods; nevertheless, it is believed that calorimetric tests could be a useful preliminary stage for quality testing. The calorimetric technique allows the detection of the adulterant (seed oils or refined olive oil), oil origin, and possible photo-oxidation degradation processes, before more complex and expensive procedures and analyses are applied.

Discriminant analysis of edible oils and fats by FTIR, FT-NIR and FT-Raman spectroscopy

The goals of this study were to use Fourier transform mid-infrared (FTIR), near-infrared (FT-NIR) and Raman (FT-Raman) spectroscopy for discrimination among 10 different edible oils and fats, and to compare the performance of these spectroscopic methods for edible oil/fat study. The spectral features of edible oils and fats were studied and the unsaturation bond (C C) in IR and Raman spectra was identified and used for discriminant analysis. Linear discriminant analysis (LDA) and canonical variate analysis (CVA) were used for the discrimination and classification of different edible oils and fats based on spectral data. FTIR spectroscopy was found to be the most efficient in classification of oils and fats when used with CVA and yielded about 98% classification accuracy, followed by FT-Raman (94%) and FT-NIR (93%) methods; however, the number of factors were much higher for FT-Raman and FT-NIR methods. Overall, results demonstrated that FTIR, FT-NIR and FT-Raman techniques can be used to rapidly and simply determine the authenticity of edible oils and fats with chemometric analysis.

A comparison of mid‐infrared and raman spectroscopies for the authentication of edible oils

AbstractRobust, routine, and rapid instrumental methods for the determination of the authenticity of edible oils, and the detection of adulteration, are continually being sought. In this paper, we compare mid‐infrared and Raman spectroscopies for their ability to discriminate between oils of differing botanical origin and for their ability to detect added adulterants. Furthermore, we used sufficient numbers of samples to permit a comparison of some of the chemometric methods (linear discriminant analysis, artificial neural networks) available and looked at the results obtained when the two spectroscopic datasets were combined. We show that mid‐infrared spectroscopy, in combination with linear discriminant analysis, gave the best classification rates and adulteration detection levels compared to Raman or combined data.