News

Honey is one of the foods susceptible to extension and adulteration with exogenous sugars. Whereas there is a well established test for C4 sugar (cane or corn based sysrups) adulteration using EA-IRMS (elemental analyser -isotope ratio mass spectrometry), detection of C3 sugar syrups (rice and beet sugar) is more difficult. In this study, an approach combining Fourier-transform infrared spectroscopy (FTIR) and chemometrics was developed for a rapid screening tool to detect potential adulteration of honey with either rice or corn syrup. A set of 46 authentic and 39 commercial honey samples were collected and adulterated samples of between 1-16% with rice syrup and 3-15% corn syrup were prepared, and their FTIR spectra determined. A single class soft independent modeling of class analogy (SIMCA) model was developed on the spectra of the set of commercial and authentic honey samples. The SIMCA model was externally validated with a set of calibration-independent authentic and commercial honey control samples, and those spiked with rice and corn syrups in the 1-16% concentration range. The authentic and commercial honey test samples were correctly predicted with a 88.3% classification rate. High accuracy was also found in predicting the rice and corn syrup spiked samples above 7% concentration range, yielding 97.6% and 94.8% correct classification rates, respectively.  

Read the full open access paper

This study used Fourier transform infrared spectroscopy (FTIR), visible near-infrared spectroscopy (Vis-NIR) and excitation-emission matrix fluorescence spectroscopy (EEMs) combined with chemometrics to distinguish different types of edible vegetable oils. A set of 147 samples of five vegetable oils from different brands were analysed by the three different spectroscopic methods. After chemometric analysis of the spectra, the total correct recognition rate of the training set and prediction set of FTIR spectra was 100% for both, and for Vis-NIR spectra was 100% and 97.6% based on the PLS-DA method. However, the total correct recognition rate of training set and prediction set of EEMs data based on N-PLS-DA method was only 69.39% and 75.51%, respectively. The comparative study showed that FTIR and Vis-NIR combined with chemometrics were more suitable for vegetable oil species identification than EEMs technique, probably because of a small amount of fluorophores in the oils.

Read the abstract here

 The popularity of spelt (Triticum spelta) is growing, and there is a need for a rapid method to authenticate it, and especially to detect adulteration by common wheat. In this study, an attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) method was developed, and combined with orthogonal partial least square discriminant analysis (OPLS-DA). A validation set of spelt and common wheat provided good discrimination between the two cereals. Also, adulterated samples were prepared as an external validation set, and the developed OPLS-DA model identified the spelt-common wheat mixtures as a separate class highlighting its strong predictive power. 

Read the abstract here

This review investigates the feasibility of different non-destructive techniques used for authenticating meat products, which could provide real-time monitoring in the near future. The spectroscopic techniques reviewed are NIR (near infrared), MIR (mid-infrared), FTIR (Fourier transform infrared), and Raman. The imaging techniques discussed are colour imaging, hyperspectral imaging and Xray imaging with computed technology. The advantages of these techniques is that they can be applied in-situ, and they give rapid results, but calibration procedures are laborious. In addition, the results are influenced by scanning times, sample to detector distance and environmental factors such as ambient temperature, humidity, illumination conditions, and sample temperature, the latter can differ in meat processing facilities. However, it is hoped that the application of these techniques will be easier with the improvement in instrumental technology, the availability of high-speed computers with appropriate storage capacity, and the development of appropriate chemometric procedures.

Read the full paper here

Maple syrup, the concentrated sap of Acer saccharum March, is sought after for its unique flavour and taste. As a popular and high value product, it is increasingly susceptible to adulteration by other sugar syrups. This review looks at most recent advances in the analytical methods used for detecting the different types of maple syrup adulteration.It concludes that SpectrAcer and nuclear magnetic resonance (NMR) are the most efficient methods for detection of maple syrup adulteration. SpectrAcer, an automated spectroscopy sytem developed by the Canadian company Acer, based reflected light at different wavelengths using the syrup's fluorescence properties with UV, and sugar composition at other wavelengths.

Read the abstract here

The use of pork and porcine ingredients is banned in halal and kosher foods. This review by Indonesian researchers examines the various methods from DNA analysis, FTIR spectroscopic analysis, chromatography to electronic nose, that have been used to detect porcine DNA, pork, pork gelatine, and lard in meat products.

Read the full paper  

Garlic is widely used in cooking all over the world. Researchers at Queens University Belfast have verified whether NIR (near infrared) and FTIR (Fourier transform infrared) spectroscopy with chemometric analysis can detect garlic mixed with possible adulterants. Authentic and adulterated garlic (with talc, maltodextrin, corn starch, cornflour, peanut butter powder, sodium caseinate, potato starch, rice flour, cassava and white maize meal) samples were prepared at 20–90% levels, and NIR and FTIR spectra of the samples obtained. Principal component analysis (PCA) models were created to establish if there was separation of garlic from the adulterants.Orthogonal partial least squares – discriminant analysis (OPLS-DA) models were then developed to be able to detect and classify the levels of adulteration correctly using both NIR and FTIR.

Read the abstract

Vanilla is a high value flavouring used in ice cream, desserts and confectionery, and mainly grown in Madagascar. Synthetic vanillin and biovanillin (produced by fermentation) are cheaper. By using SIRA (stable isotope ratio analysis) to look at the δ13C, it is possible to distinguish between the three types of vanilla flavouring. The method was tested on market samples of yoghurt and ic cream. Also FTIR (Fourier Transform Infrared) spectoscopy with chemometric analysis was calibrated with authentic samples of black pepper so that it was possible to detect the adulteration of ground black pepper with black pepper husk and defatted spent material. The research was undertaken as a Ph.D registered at the Technical University of Denmark, but carried out at the Danish National Food Institute and IGFS - Queens University Belfast.  

Read the article or the Ph.D thesis 

The illegal practice of adding sucrose to milk has increased in recent years. Sucrose is used as an adulterant of reconstituted milk to increase the total solids content. This research developed the use of  FTIR spectroscopy in combination with multivariate chemometric modelling for the differentiation and quantification of sucrose in cow milk. Trial samples of sucrose adulterated milk from 0.5 - 7.5% were prepared and analysed by FTIR. Chemometric analysis was performed on the spectra, and partial least squares regression (PLS-R) showed the best prediction of adulteration with a detection level of 0.5% w/v sucrose adulteration. The method is simple, non-destructive, quick and needs minimal samples preparation. 

Read the abstract here

Polish researchers have published a paper on the development of rapid, simple, and non-destructive analytical procedure for discrimination and authentication of whiskies originating from Scotland, Ireland and USA  as well as time of maturation (two, three, six and twelve years). Combination of data from Fourier Transform Infrared Spectroscopy (FTIR) with statistical analysis was used to construct eight discriminant models. The models obtained permitted whiskies from Scotland, Ireland, and USA to be distinguished from each other, and 2 and 3 years old beverages from 6 and 12 years old whiskies. Results show that 100% of samples were correctly classified in models discriminating American and Scottish whiskies or 2-year-old and 6-year-old American whiskies. American whiskies were classified correctly in all models, which may suggest its considerable chemical difference compared to whisky produced in Scotland or Ireland. 

  Read the full paper here

Researchers at Rutgers University, NJ, have developed a rapid method using a portable FTIR (Fourier Transform Infrared) Spectrometer to distinguish between synthesised Omega-3 ethyl esters and natural unprocessed fish oil. Using a commercial liquid transmission accessory, small samples of fish oil at three thicknesses (25,50 and 100 microns) permit the differentiation by focussing on different vibrational bands. A survey of fish oil capsules sold on the US market found about 80% of the products tested that are marketed as fish oil, contain oil that has been chemically altered from natural fish oil.

Read the full article at: fish oil authenticity

The Danish Consumer Organisation, Forbrugerrådet Tænk, collected 10 samples of oregano from supermarkets and stores around Copenhagen during the summer. The samples were sent for analysis by FTIR and chemometric modelling followed by mass spectrometry for confirmation. Three of the samples had only 50% oregano, and a fourth 70% oregano, the remainder was dried plant material from olive leaves and myrtle. 

Read the article at: Danish oregano tests

Researchers applying a multi-step approach using HPLC, UV–Vis, FT-IR and NMR analyses, uncovered a new type of adulteration of a commercial product labelled as “saffron”, and sold packed in powder form in a major consuming country.  Applying the four methods and NMR data from in-house databases, they uncovered a  “tailor-made” case of 100% substitution of saffron by a mixture of exogenous chemical compounds in such a way that the commercial product would approximately mimic not only the appearance of saffron but also its UV–Vis spectrum and specific absorbance values. The findings indicated a sophisticated practice, including total substitution of saffron constituents by tartrazine and sunset yellow along with propane-1,2-diol, propan-2-ol and acylglycerols, probably as emulsifier agents. 

Read the abstract at: Multi-step approach uncovers saffron fraud