Characterization and Authentication of Significant Chinese Edible Oilseed Oils by Stable Carbon Isotope Analysis

Geographical origin classification of peanuts and processed fractions using stable isotopes

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Stable isotopes of peanuts and their different fractions are investigated.

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Stable C, N, O and H isotopes of peanuts are used to assign production origin.

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Peanuts are leguminous plants and fix nitrogen from the atmosphere.

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Peanut δ¹⁵N is unaffected by processing and indicates soil nitrification processes.

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LDA model achieved higher classification rates than k-NN and SVM models.

This study investigates the use of stable isotopes (C, N, H, and O) to characterize the geographical origin of peanuts along with different peanut fractions including whole peanut kernel, peanut shell, delipidized peanuts and peanut oil. Peanut samples were procured in 2017 from three distinctive growing regions (Shandong, Jilin, and Jiangsu) in China. Peanut processing significantly influenced the δ¹³C, δ²H, and δ¹⁸O values of different peanut fractions, whereas δ¹⁵N values were consistent across all fractions and unaffected by peanut processing. Geographical differences of peanut kernels and associated peanut fractions showed a maximum variance for δ¹⁵N and δ¹⁸O values which indicated their strong potential to discriminate origin. Different geographical classification models (SVM, LDA, and k-NN) were tested for peanut kernels and associated peanut fractions. LDA achieved the highest classification percentage, both on the training and validation sets. Delipidized peanuts had the best classification rate compared to the other fractions.

Detection of camellia oil adulteration using chemometrics based on fatty acids GC fingerprints and phytosterols GC-MS fingerprints

The fatty acid, squalene, and phytosterols, coupled to chemometrics were utilized to detect the adulteration of camellia oil (CAO) with palm superolein (PAO), refined olive oil (ROO), high oleic- sunflower oil (HO-SUO), sunflower oil (SUO), corn oil (COO), rice bran oil (RBO), rice oil (RIO), peanut oil (PEO), sesame oil (SEO), soybean oil (SOO), and rapeseed oil (RAO). CAO was characterized with higher triterpene alcohols, thus differentiated from other vegetable oils in principle component analysis (PCA). Using partial least squares-discriminant analysis (PLS-DA), CAO adulterated with PAO, ROO, HO-SUO, SUO, COO, RBO, RIO, PEO, SEO, SOO, RAO (5%-100%, w/w), could be classified, especially higher than 92.31% of the total discrimination accuracy, at an adulterated ratio above 30%. With less than 22 potential key markers selected by the variable importance in projection (VIP), the optimized PLS models were confirmed to be accurate for the adulterated level prediction in CAO.

Rapid Classification and Quantification of Camellia (Camellia oleifera Abel.) Oil Blended with Rapeseed Oil Using FTIR-ATR Spectroscopy

Currently, the authentication of camellia oil (CAO) has become very important due to the possible adulteration of CAO with cheaper vegetable oils such as rapeseed oil (RSO). Therefore, we report a Fourier transform infrared (FTIR) spectroscopic method for detecting the authenticity of CAO and quantifying the blended levels of RSO. In this study, two characteristic spectral bands (1119 cm^-1 and 1096 cm^-1) were selected and used for monitoring the purity of CAO. In combination with principal component analysis (PCA), linear discriminant analysis (LDA), and partial least squares regression (PLSR) analysis, qualitative and quantitative methods for the detection of camellia oil adulteration were proposed. The results showed that the calculated I₁₁₁₉/I₁₀₉₆ intensity ratio facilitated an initial check for pure CAO and six other edible oils. PCA was used on the optimized spectral region of 1800-650 cm^-1. We observed the classification of CAO and RSO as well as discrimination of CAO with RSO adulterants. LDA was utilized to classify CAO from RSO. We could differentiate and classify RSO adulterants up to 1% v/v. In the quantitative PLSR models, the plots of actual values versus predicted values exhibited high linearity. Root mean square error of calibration (RMSEC) and root mean square error of cross validation (RMSECV) values of the PLSR models were 1.4518%-3.3164% v/v and 1.7196%-3.8136% v/v, respectively. This method was successfully applied in the classification and quantification of CAO adulteration with RSO.

Stable isotope signatures (δ2 H-, δ13 C-, δ15 N-values) of walnuts (Juglans regia L.) from different regions in Germany

BACKGROUND

Walnuts (Juglans regia L.) are considered of high value for human nutrition and are cultivated worldwide. With globalization, however, the demand for regional products has increased. Isotopic fingerprints (δ² H-, δ¹⁵ N- and δ¹³ C-values (‰)) created by means of stable isotope ratio mass spectrometry provide the possibility of tracing the geographical provenance of plant foods.

RESULTS

Authentic walnut samples from different geographical regions in Germany could be separated from each other by means of their bulk δ² H-values (‰) with samples from northern regions being more enriched in ² H than samples collected from southern Germany. Next to precipitation data, the topography of the surrounding landscape of the sampling sites was taken into account for data interpretation by the creation of approximate elevation profiles. Moreover, German walnuts could be separated from French walnuts which showed significantly higher δ² H-values (‰). Variations in annual total precipitation was reflected by the shift in δ² H-ranges (‰) depending on the harvesting year. Additionally, organic walnuts could be well separated from conventionally produced walnuts due to their distinct δ¹⁵ N-values (‰) which could be ascribed to a cultivation practice common for organic farming.

CONCLUSIONS

The data presented here outlined the potential of determining isotopic fingerprints of walnuts from different sites within one country for tracing their regional origin and revealing their cultivation conditions. Including topographic characteristics between the sampling locations as well as precipitation data helped to even differentiate walnuts from two adjoining countries. © 2019 The Authors. Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Authentication of Processed Epimedii folium by EA-IRMS

Processing of crude drug is a key character of traditional Chinese medicine (TCM), which could enhance the efficacy and/or reduce the toxicity of crude drugs to fulfill different requirements of TCM clinical practice. Epimedii folium (EF) is a widely used TCM. As a traditional method of TCM, EF is processed with refined mutton fat before being used in clinical practice. It has been reported that processing EF with mutton fat could improve the bioavailability and intestinal absorption of epimedium flavonoids and thus enhances the pharmacological effects. For economic benefits, it is possible to adulterate processed EF with unprocessed drug or process EF with cheaper plant oils. In the present study, 17 batches of crude and processed EF samples were collected from the Chinese market and 10 batches of replica processed drugs were prepared with different edible plant oils and animal fats in our laboratory. Elemental analyzer coupled with isotopic ratio mass spectrometry (EA-IRMS) was applied to determine the δ ¹³C values of the cyclohexane extracts of those samples. Significant differences could be observed in the results. EA-IRMS could be used to discriminate raw EF, processed EF, and EF processed with C3 plant oils.

Application of Red Mud in Wastewater Treatment

Red mud (RM) is an industrial waste produced in large amounts during alumina extraction from bauxite. Its disposal generates serious environmental pollution due to high alkalinity. Therefore, a strategy for the effective utilization of RM must be developed. For instance, RM may be transformed into useful products, such as adsorbents. Given its high concentrations of aluminum oxides, iron oxides, titanium oxides, silica oxides, and hydroxides, RM may be developed as a cheap adsorbent for the removal of various ions from aqueous solution and soils (e.g., metal and non-metal ions, phenolic compounds, and dyes) and waste gas purification (sulfide and carbide). This review summarizes the background, properties, and applications of RM as an adsorbent. Proper approaches of removing metal and non-metal elements from wastewater are also systematically reviewed and compared. Emphasis is placed on the surface modification of RM to obtain high adsorption. Finally, the scope for future research in this area for RM is discussed in depth.

¹H-NMR Profiling and Carbon Isotope Discrimination as Tools for the Comparative Assessment of Walnut (Juglans regia L.) Cultivars with Various Geographical and Genetic Origins-A Preliminary Study

The aim of the study was to investigate the differences between walnut genotypes of various geographical and genetic origins grown under the same or different environmental conditions. The biological material analyzed consisted in walnut kernels of 34 cultivars, nine advanced selections, and six hybrids harvested in 2015 and 2016, summing up to a total of 64 samples. The walnuts, walnut oil, and residue were characterized in respect to their chemical (proximate composition—fat, protein, nutritional value, fatty acids profile by ¹H-NMR) and carbon-13 isotopic composition. The data was used to statistically discriminate the cultivars according to composition, geographical area of origin, and year of harvest, comparing the Romanian cultivars, selections, and hybrids with the internationally available ones.

Stimulated Brillouin scattering in combination with visible absorption spectroscopy for authentication of vegetable oils and detection of olive oil adulteration

Vegetable oils provide high nutritional value in the human diet. Specifically, extra virgin olive oil (EVOO) possesses a higher price than that of other vegetable oils. Adulteration of pure EVOO with other types of vegetable oils has attracted increasing attentions. In this work, a stimulated Brillouin scattering (SBS) combined with visible absorption spectroscopy method is proposed for authentication of vegetable oils and detection of olive oil adulteration. The results provided here have demonstrated that the different vegetable oils and adulteration oils exhibit significant differences in normalized absorbance values of two relevant wavelengths (455 and 670 nm) and frequency shifts of SBS. The normalized absorbance values of all spectra at the two relevant wavelengths of 670 nm and 455 nm linearly decrease with the increase of the adulteration concentration. The Brillouin frequency shifts exponentially increase with the increase of the adulteration concentration. Due to non-destructive and requiring no sample pretreatment procedure, this method can be effectively employed for authentication and detection of oils adulteration.

Stable Carbon Isotope Composition of the Lipids in Natural Ophiocordyceps sinensis from Major Habitats in China and Its Substitutes

Ophiocordyceps sinensis is one rare medicinal fungus produced in the Qinghai-Tibetan Plateau. Its quality and price varies hugely with different habitat, and its numerous substitutes have sprung up in functional food markets. This paper aims to discriminate the geographic origin of wild O. sinensis and its substitutes via element analyzer-isotope ratio mass spectrometry and gas chromatography-isotope ratio mass spectrometry. The δ13C values of major fatty acids in the lipids of O. sinensis are characterized unanimously by the variation relation C18:0 < C18:2 ≈ C16:0 < C18:1, while their fluctuation intervals are notably different between those of neutral and polar lipids. The comparative analysis of the δ13C ratios of major fatty acids in lipids of O. sinensis suggests that the δ13C patterns may be sensitive potential indicators to discriminate its geographical origin. The δ13C values of individual major fatty acids of lipids from the cultivated stromata of Cordyceps militaris (SCM), the fermented mycelia of Hirsurella sinensis (FMH) and Paecilomyces epiali (FMP) range from -31.2‰ to -29.7‰, -16.9‰ to -14.3‰, and -26.5‰ to -23.9‰, respectively. Their δ13C pattern of individual major fatty acids may be used as a potential indicator to discriminate the products of natural O. sinensis and its substitutes.

Fungus-larva relation in the formation of Cordyceps sinensis as revealed by stable carbon isotope analysis

For more than one thousand years, Cordyceps sinensis has been revered as a unique halidom in the Qinghai-Tibetan Plateau for its mysterious life history and predominant medicinal values. This mysterious fungus-larva symbiote also attracted the over-exploitation, while several problems on the initial colonization of Ophiocordyceps sinensis in the host larva have constrained artificial cultivation. In this work, stable carbon isotope analysis was employed to analyse the subsamples of C. sinensis from 5 representative habitats. The results demonstrated that these samples possessed similar δ¹³C profiles, i.e., a steady ascending trend from the top to the bottom of stroma, occurrence of the δ¹³C maximum at the head, a slight decrease from the head to the end of thorax, a sharply descent trend from the end of thorax to the forepart of abdomen, and maintenance of lower δ¹³C values in the rest parts of abdomen. Based on the data, we consider that the site near the head of the host larva may be the initial target attacked by O. sinensis, and the fungus growth is closely related to the digestive tract of its host larva. The growth stages of O. sinensis are accordingly speculated as the symptom-free, symptom-appearing, and stroma-germinating stages.

Authentication of virgin olive oil by a novel curve resolution approach combined with visible spectroscopy

Adulteration of olive oil is not only a major economic fraud but can also have major health implications for consumers. In this study, a combination of visible spectroscopy with a novel multivariate curve resolution method (CR), principal component analysis (PCA) and linear discriminant analysis (LDA) is proposed for the authentication of virgin olive oil (VOO) samples. VOOs are well-known products with the typical properties of a two-component system due to the two main groups of compounds that contribute to the visible spectra (chlorophylls and carotenoids). Application of the proposed CR method to VOO samples provided the two pure-component spectra for the aforementioned families of compounds. A correlation study of the real spectra and the resolved component spectra was carried out for different types of oil samples (n=118). LDA using the correlation coefficients as variables to discriminate samples allowed the authentication of 95% of virgin olive oil samples.

Control of origin of sesame oil from various countries by stable isotope analysis and DNA based markers--a pilot study

The indication of origin of sesame seeds and sesame oil is one of the important factors influencing its price, as it is produced in many regions worldwide and certain provenances are especially sought after. We joined stable carbon and hydrogen isotope analysis with DNA based molecular marker analysis to study their combined potential for the discrimination of different origins of sesame seeds. For the stable carbon and hydrogen isotope data a positive correlation between both isotope parameters was observed, indicating a dominant combined influence of climate and water availability. This enabled discrimination between sesame samples from tropical and subtropical/moderate climatic provenances. Carbon isotope values also showed differences between oil from black and white sesame seeds from identical locations, indicating higher water use efficiency of plants producing black seeds. DNA based markers gave independent evidence for geographic variation as well as provided information on the genetic relatedness of the investigated samples. Depending on the differences in ambient environmental conditions and in the genotypic fingerprint, a combination of both analytical methods is a very powerful tool to assess the declared geographic origin. To our knowledge this is the first paper on food authenticity combining the stable isotope analysis of bio-elements with DNA based markers and their combined statistical analysis.