Evaluation of methodologies to determine vegetable oil species present in oil mixtures: Proposition of an approach to meet the EU legislation demands for correct vegetable oils labelling

An overview of nutritional profiling in foods: Bioanalytical techniques and useful protocols

Maintaining a nutritious diet is essential for humans if they want to live a healthier life. Several food businesses and food safety organizations play a significant role and offer useful ways for improving nutritional quality that assists consumers in making informed selections. Making poor food choices and consuming unhealthy meals are the main causes of non-communicable diseases (NCDs). Nutritional profiling (NP) models are developed to evaluate the nutritional value, calorie content, and the amount of micronutrients and macronutrients contained in a given food accompanied by additional details on the nutritional anomaly provided by published standard nutrients and nutritional databases. To construct an ideal nutritional model that can facilitate food consumption, bioanalytical methods such as chromatography, microscopic techniques, molecular assays, and metabolomics can be applied. With the use of these technologies, one can learn more about the health advantages of nutrition and how to prevent disease. A wider element of NP is also provided by the developing technologies in the area of nutrition research, such as nanotechnology, proteomics, and microarray technology. In this review, we are focusing on the different bioanalytical techniques and the various protocols of NP and their application and refinement of the models. We have evaluated various NP techniques currently used in the food industry for the detection of different components present in food items.

Time-resolved fluorescent lateral flow strip for easy and rapid quality control of edible oil

Gutter oil is strictly prohibited from being reprocessed back to the catering and food industry. Extensive attention has been paid to rapid screening of gutter oil to guarantee the safety of edible oil. Capsaicin, a special component of condiments, has been adopted as the marker of gutter oil. The time-resolved fluorescent microspheres are utilized for labeling of antibody to capsaicin, which are further applied for the construction of fluorescent lateral-flow-strip (LFS). By simple extraction of capsaicin with ethanol (or liquor) from the edible oil, the capsaicin can be rapid determined with the fluorescent LFS in less than 10 min. As low as 20 ng/mL capsaicin can be visually judged and 2.3 ng/mL is achieved as the detection limit by ImageJ analysis. The illegal gutter oil is also well screened with this time-resolved LFS. This method can be a useful candidate for routine quality monitoring of edible oil and a powerful tool for self-inspection at home.

Mycobiome analysis for distinguishing the geographical origins of sesame seeds

Sesame (Sesamum indicum) is one of the most widely cultivated crops in Asia and Africa. The identification of the geographical origins of sesame seeds is important for the detection of fraudulent samples. This study was conducted to build a prediction model and suggest potential biomarkers for distinguishing the geographical origins of sesame seeds using mycobiome (fungal microbiome) analysis coupled with multivariate statistical analysis. Sesame seeds were collected from 25 cities in Korea, six cities in China, and five sites in other countries (Ethiopia, India, Nigeria, and Pakistan). According to the expression of fungal internal transcribed spacer (ITS) sequences in sesame seeds, 21 fungal genera were identified in sesame seeds from various countries. The optimal partial least squares-discriminant analysis model was established by applying two components with unit variance scaling. Based on seven-fold cross validation, the predictive model had 94.4% (Korea vs. China/other countries), 91.7% (China vs. Korea/other countries), and 88.9% (other countries vs. Korea/China) accuracy in determining the geographical origins of sesame seeds. Alternaria, Aspergillus, and Macrophomina were suggested as the potential fungal genera to differentiate the geographical origins of sesame seeds. This study demonstrated that mycobiome analysis could be used as a complementary method for distinguishing the geographical origins of raw sesame seeds.

The correlation of physicochemical properties of edible vegetable oils by chemometric analysis of spectroscopic data

This work aimed to investigate and compare the composition and the physicochemical properties of 18 different sources of edible vegetable oils. A systematic study on the correlation between composition and physical properties was performed using Fourier Transform Infrared (FTIR) Spectroscopy and fatty acid chromatographic analysis. Principal component analysis of FTIR spectra is performed to classify edible oils concerning their physical properties. The results demonstrate the potentiality of the method associated with multivariate statistics analysis as powerful, fast, and non-destructive tools for characterization and quality control of edible vegetable oils.

Excitation wavelength analysis of a laser-induced fluorescence technique for quantification of extra virgin olive oil adulteration

The performance of the laser-induced fluorescence (LIF) technique is greatly affected by the excitation wavelength (EW). This study aims to find an appropriate EW that can be used for analyzing extra virgin olive oil (EVOO) adulteration quantification by comparing the effect of different EWs. The EWs of 405 nm, 450 nm, and 532 nm were selected to perform the comparative experiments. By using the three EWs in the experiments, the LIF spectra of EVOO samples adulterated with peanut oil (PO) or soybean oil (SO) in different proportions, as well as the prediction models established through different multivariate analysis algorithms were analyzed. The linear discriminant analysis (LDA) was applied for qualitative analysis, while the partial least squares regression (PLSR), backpropagation neural network, and k-nearest neighbor were employed for quantitative analysis. The results show that the performance of 450 nm EW is always superior to that of 405 and 532 nm EWs in any model, with a smaller root mean square error (RMSE). Using the LDA-PLSR model, the RMSE is 1.35% for SO adulterants and 1.36% for PO adulterants, respectively.

Improved continuous locality preserving projection for quantification of extra virgin olive oil adulteration by using laser-induced fluorescence

An optimized dimensionality reduction technique is proposed as the improved continuous locality preserving projection (ICLPP), which was developed by modifying and optimizing the weighting functions and weighting factors of the continuous locality preserving projection (CLPP) algorithm. With only one adjustable parameter, this optimized technique not only enhances CLPP's capability of maintaining the continuity of the massive data, but also results in better simplicity and adaptability of the algorithm. In this paper, the performance of ICLPP is validated through quantification analysis of the adulteration of extra virgin olive oil (EVOO) with low-cost oils based on laser-induced fluorescence spectroscopy. Through cross validation and comparative studies, ICLPP, combined with the regression algorithm, is employed to predict and screen adulteration in EVOO, and is found to generally outperform other state-of-the-art dimensionality reduction algorithms, especially for prediction of adulterants at low level (<10%). It is evidenced that the ICLPP-based framework is superior in detecting adulteration by using spectral data.

Application of terahertz spectroscopy and chemometrics for discrimination of transgenic camellia oil

Discrimination of transgenic edible oil has become the focus of attention in the field of food safety. In this paper, we propose a method for discrimination of transgenic edible oils by using terahertz spectroscopy combine with weighted linear discriminant analysis (WLDA). To evaluate the lustiness of the model, we employ successive projection arithmetic (SPA) and partial least squares (PLS) to verify the discrimination performance through variable selection. The results demonstrate that the SPA-WLDA model has higher classification accuracy than PLS-WLDA. In conclusion, terahertz spectroscopy is coupled with chemometrics is an effective method for discriminating various types of transgenic edible oils.

Geographical discrimination of palm oils (Elaeis guineensis) using quality characteristics and UV-visible spectroscopy

This preliminary study demonstrated the possibility of discriminating geographical origin of palm oils using conventional quality characteristics and UV-visible spectroscopy. A total of 60 samples, 20 from each region (North (N), South (S), and Central (C)) of Ondo State Nigeria, were analyzed for their quality characteristics and UV-visible spectra. Principal component analysis (PCA) and orthogonal projection to latent structure discriminant analysis (OPLS-DA) were applied to elaborate the data. Models were built on the most informative portion of the spectra (250-550 nm) as: untreated (without pretreatment) and standard normal variate-second-derivative-treated (SNV+2der) data matrices. OPLS-DA classification models were validated by independent prediction sets and cross-validation. PCA score plots of both chemical and spectral data matrices revealed geographical distinction between the palm oil samples. Significantly high carotene content, free fatty acids, acid value, and peroxide value distinguished Central palm oils. K extinction values, color density, and chlorophyll content were the most important quality parameters separating North oil samples. In the discriminant models, over 95% and 85% percent correct classification were recorded for spectral and chemical data, respectively. These results cannot be considered exhaustive because of the limited sample size used. However, the study suggested a potential analytical technique suitable for geographical origin authentication of palm oils with additional advantages that include the following: speed, low cost, and minimal waste.

Modern analytical methods for the detection of food fraud and adulteration by food category

This review provides current information on the analytical methods used to identify food adulteration in the six most adulterated food categories: animal origin and seafood, oils and fats, beverages, spices and sweet foods (e.g. honey), grain-based food, and others (organic food and dietary supplements). The analytical techniques (both conventional and emerging) used to identify adulteration in these six food categories involve sensory, physicochemical, DNA-based, chromatographic and spectroscopic methods, and have been combined with chemometrics, making these techniques more convenient and effective for the analysis of a broad variety of food products. Despite recent advances, the need remains for suitably sensitive and widely applicable methodologies that encompass all the various aspects of food adulteration. © 2017 Society of Chemical Industry.

FT-NIR the method of choice to verify the authenticity of extra virgin olive oils

Fourier transform near infrared spectroscopy was recently demonstrated to be an excellent method to evaluate the authenticity and adulteration of extra virgin olive oil. Since this method is matrix dependent, it takes a chemical fingerprint of all the components which sets it apart from the targeted methods. Careful examinations of the Fourier transform near infrared spectra lead to the identification of a minor carbonyl overtone absorption at 5269 cm−1 associated with the volatile fraction in extra virgin olive oil that appears to be a reliable indicator of authenticity. The same spectra were used to identify the fatty acids present in the oil using models based on comparison to accurate GC data. Gravimetric mixtures of extra virgin olive oil with refined edible oils were then prepared to develop PLS1 calibration models to identify possible adulterants and by how much. The great varietal difference in olive oils made it necessary to develop four unique sets of PLS1 calibration models for each extra virgin olive oil variety. As a result, an extra virgin olive oil acceptance specification was established.

Classification and quantification of palm oil adulteration via portable NIR spectroscopy

Short wave near infrared spectroscopy (NIR) method was used to detect the presence of lard adulteration in palm oil. MicroNIR was set up in two different scan modes to study the effect of path length to the performance of spectral measurement. Pure and adulterated palm oil sample were classified using soft independent modeling class analogy (SIMCA) algorithm with model accuracy more than 0.95 reported for both transflectance and transmission modes. Additionally, by employing partial least square (PLS) regression, the coefficient of determination (R²) of transflectance and transmission were 0.9987 and 0.9994 with root mean square error of calibration (RMSEC) of 0.5931 and 0.6703 respectively. In order to remove the uninformative variables, variable selection using cumulative adaptive reweighted sampling (CARS) has been performed. The result of R² and RMSEC after variable selection for transflectance and transmission were improved significantly. Based on the result of classification and quantification analysis, the transmission mode has yield better prediction model compared to the transflectance mode to distinguish the pure and adulterated palm oil.

A tandem mass spectrometry method based on selected ions detects low-abundance phenolics in black tea - theatridimensins as products of the oxidative cascade

RATIONALE

Mixtures of phenolics are widespread in plant-derived food products, for instance black tea. Detailed compositional analysis of phenolics present is important for quality control. Characterization of low-abundance compounds often requires extensive purification; hence, the need for rapid screening methods to annotate compounds in complex mixtures without extensive sample preparation. Opportunities of ultra-high performance liquid chromatography/tandem mass spectrometry (UHPLC/MS) as tool in a rapid screening method are discussed for black tea analysis, with the two-step-oxidation product theatridimensin (T3D) as example.

METHODS

Three MS screening methods were compared for their ability to tentatively annotate two-step-oxidation products in black teas without the need for prior fractionation: (i) full MS; (ii) tandem mass spectrometry (MS/MS) on selected ions; and (iii) selected reaction monitoring (SRM), in combination with post-analysis extracted ion chromatography. A model system of theaflavin (TF), epicatechin (EC) and tyrosinase was used to prepare the two-step-oxidation product T3D, consisting of three oligomerized catechin subunits. Commercial teas were screened for the occurrence of T3Ds.

RESULTS

The MS(2) fragmentation pattern of T3D was compared with that of an isomeric catechin trimer from black tea, TFsEC. MS(2) signature fragments were found to distinguish the two isomers, i.e. m/z 617 for T3D and m/z 563 for TFsEC. The MS screening methods, MS/MS on selected ions and SRM, both enabled monitoring MS(2) data of compounds present in low abundance. The former provided the most complete MS(2) data set, which facilitated the discovery of another isomer, i.e. theaflavate A. T3Ds, TFsECs, and theaflavate A could be tentatively annotated in all tested tea samples.

CONCLUSIONS

When exploring black tea for the occurrence of two-step-oxidation products, the use of MS/MS on selected ions combined with extracted ion chromatography proved to be the most suitable. The occurrence of T3Ds and T3Dgs in various black teas was shown for the first time and the 'oxidative cascade hypothesis' was extended with novel oxidation products. Copyright © 2016 John Wiley & Sons, Ltd.

A comprehensive strategy to detect the fraudulent adulteration of herbs: The oregano approach

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Two tier strategy proposed to detect oregano fraud.

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FT-IR screening and HR-LC-MS confirmatory methods developed.

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Unique biomarkers discovered in adulterants by HR-LC-MS.

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Chemometric calibration models generated.

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24% of oregano samples tested in UK/Ireland were found to be adulterated.

Fraud in the global food supply chain is becoming increasingly common due to the huge profits associated with this type of criminal activity. Food commodities and ingredients that are expensive and are part of complex supply chains are particularly vulnerable. Both herbs and spices fit these criteria perfectly and yet strategies to detect fraudulent adulteration are still far from robust. An FT-IR screening method coupled to data analysis using chemometrics and a second method using LC-HRMS were developed, with the latter detecting commonly used adulterants by biomarker identification. The two tier testing strategy was applied to 78 samples obtained from a variety of retail and on-line sources. There was 100% agreement between the two tests that over 24% of all samples tested had some form of adulterants present. The innovative strategy devised could potentially be used for testing the global supply chains for fraud in many different forms of herbs.

Chemometric study of Andalusian extra virgin olive oils Raman spectra: Qualitative and quantitative information

Authentication of extra virgin olive oil (EVOO) is an important topic for olive oil industry. The fraudulent practices in this sector are a major problem affecting both producers and consumers. This study analyzes the capability of FT-Raman combined with chemometric treatments of prediction of the fatty acid contents (quantitative information), using gas chromatography as the reference technique, and classification of diverse EVOOs as a function of the harvest year, olive variety, geographical origin and Andalusian PDO (qualitative information). The optimal number of PLS components that summarizes the spectral information was introduced progressively. For the estimation of the fatty acid composition, the lowest error (both in fitting and prediction) corresponded to MUFA, followed by SAFA and PUFA though such errors were close to zero in all cases. As regards the qualitative variables, discriminant analysis allowed a correct classification of 94.3%, 84.0%, 89.0% and 86.6% of samples for harvest year, olive variety, geographical origin and PDO, respectively.

Effect of ultrasonic treatment on total phenolic extraction from Lavandula pubescens and its application in palm olein oil industry

The aims of the current study were to evaluate the best technique for total phenolic extraction from Lavandula pubescens (Lp) and its application in vegetable oil industries as alternatives of synthetic food additives (TBHQ and BHT). To achieve these aims, three techniques of extraction were used: ultrasonic-microwave (40 kHz, 50 W, microwave power 480 W, 5 min), ultrasonic-homogenizer (20 kHz, 150 W, 5 min) and conventional maceration as a control. By using the Folin-Ciocalteu method, the total phenolic contents (TPC) (mg gallic acid equivalent/g dry matter) were found to be 253.87, 216.96 and 203.41 for ultrasonic-microwave extract, ultrasonic-homogenizer extract and maceration extract, respectively. The ultrasonic-microwave extract achieved the higher scavenger effect of DPPH (90.53%) with EC50 (19.54 μg/mL), and higher inhibition of β-carotene/linoleate emulsion deterioration (94.44%) with IC50 (30.62 μg/mL). The activity of the ultrasonic-microwave treatment could prolong the induction period (18.82 h) and oxidative stability index (1.67) of fresh refined, bleached and deodorized palm olein oil (RBDPOo) according to Rancimat assay. There was an important synergist effect between citric acid and Lp extracts in improving the oxidative stability of fresh RBDPOo. The results of this work also showed that the ultrasonic-microwave assisted extract was the most effective against Gram-positive and Gram-negative strains that were assessed in this study. The uses of ultrasonic-microwave could induce the acoustic cavitation and rupture of plant cells, and this facilitates the flow of solvent into the plant cells and enhances the desorption from the matrix of solid samples, and thus would enhance the efficiency of extraction based on cavitation phenomenon.

Chemometric applications to assess quality and critical parameters of virgin and extra-virgin olive oil. A review

Today virgin and extra-virgin olive oil (VOO and EVOO) are food with a large number of analytical tests planned to ensure its quality and genuineness. Almost all official methods demand high use of reagents and manpower. Because of that, analytical development in this area is continuously evolving. Therefore, this review focuses on analytical methods for EVOO/VOO which use fast and smart approaches based on chemometric techniques in order to reduce time of analysis, reagent consumption, high cost equipment and manpower. Experimental approaches of chemometrics coupled with fast analytical techniques such as UV-Vis spectroscopy, fluorescence, vibrational spectroscopies (NIR, MIR and Raman fluorescence), NMR spectroscopy, and other more complex techniques like chromatography, calorimetry and electrochemical techniques applied to EVOO/VOO production and analysis have been discussed throughout this work. The advantages and drawbacks of this association have also been highlighted. Chemometrics has been evidenced as a powerful tool for the oil industry. In fact, it has been shown how chemometrics can be implemented all along the different steps of EVOO/VOO production: raw material input control, monitoring during process and quality control of final product.

Simultaneous determination of capsaicin and dihydrocapsaicin for vegetable oil adulteration by immunoaffinity chromatography cleanup coupled with LC-MS/MS

Capsaicin and dihydrocapsaicin were selected as adulteration markers to authenticate vegetable oils. In this study, a method of immunoaffinity chromatography (IAC) combined with liquid chromatography-tandem mass spectrometry was established for the determination of capsaicin and dihydrocapsaicin in vegetable oils. In this method, immunosorbents were obtained by covalently coupling highly specific capsaicinoid polyclonal antibodieswith CNBr-activated Sepharose 4B, and then packed into a polyethylene column. In this paper, the major parameters affecting IAC extraction efficiency, including loading, washing and eluting conditions, were also investigated. The IAC column displayed high selectivity for capsaicin and dihydrocapsaicin with the maximum capacity of 240ng. The limit of detection (LOD) and limit of quantification (LOQ) for capsaicin were calculated as 0.02 and 0.08μgkg(-1), and for dihydrocapsaicin were 0.03 and 0.10μgkg(-1). The recoveries of capsaicin and dihydrocapsaicin in oil samples were in the range of 87.3-95.2% with the relative standard deviation (RSD) of less than 6.1%. The results indicated that capsaicinoid compounds could not be found in edible vegetable oils. Therefore, the proposed method is simple, reliable and adequate for routine monitoring of capsaicinoid compounds in vegetable oils and has an excellent potential for detection of adulteration with inedible waste oil.

TDDFT prediction of UV-vis absorption and emission spectra of tocopherols in different media

We use the TDDFT/PBE0/6-31+G* method to determine the electronic absorption and emission energies, in different media, of the four forms of tocopherol, which differ by the number and the position of methyl groups on the chromanol. Geometries of the ground state S0 and the first singlet excited state S1 were optimized in the gas phase, and various solvents. The solvent effect is evaluated using an implicit solvation model (IEF-PCM). Our results are compared to the experimental ones obtained for the vitamin E content in several vegetable oils. For all forms of tocopherols, the HOMO-LUMO first vertical excitation is a π-π* transition. Gas phase and non-polar solvents (benzene and toluene) give higher absorption wavelengths than polar solvents (acetone, ethanol, methanol, DMSO, and water); this can be interpreted by a coplanarity between the O-H group and the chroman, allowing a better electronic resonance of the oxygen lone pairs and the aromatic ring, and therefore giving an important absorption wavelength, whereas the polar solvents give high emission wavelengths comparatively to gas phase and non-polar solvents. Fluorescence spectra permit the determination, the separation, and the identification of the four forms of tocopherols by a large difference in emission wavelength values. Graphical Abstract Scheme from process methodological to obtain the absorption and emission spectra for tocopherols.

Discrimination of honey of different floral origins by a combination of various chemical parameters

Honey is a high value food commodity with recognized nutraceutical properties. A primary driver of the value of honey is its floral origin. The feasibility of applying multivariate data analysis to various chemical parameters for the discrimination of honeys was explored. This approach was applied to four authentic honeys with different floral origins (rata, kamahi, clover and manuka) obtained from producers in New Zealand. Results from elemental profiling, stable isotope analysis, metabolomics (UPLC-QToF MS), and NIR, FT-IR, and Raman spectroscopic fingerprinting were analyzed. Orthogonal partial least square discriminant analysis (OPLS-DA) was used to determine which technique or combination of techniques provided the best classification and prediction abilities. Good prediction values were achieved using metabolite data (for all four honeys, Q(2)=0.52; for manuka and clover, Q(2)=0.76) and the trace element/isotopic data (for manuka and clover, Q(2)=0.65), while the other chemical parameters showed promise when combined (for manuka and clover, Q(2)=0.43).