Determination of organic milk authenticity using carbon and nitrogen natural isotopes

Analytical strategies based on untargeted and targeted metabolomics for the accurate authentication of organic milk from Jersey and Yak

Organic milk has a high risk of food fraud as it can easily be adulterated with non-organic milk. This study aimed to identify metabolite markers for assessing the authenticity of organic milk from Jersey and Yak. In the untargeted strategy, ultra-high performance liquid chromatography-Q Exactive HF-X mass spectrometer coupled with chemometrics analysis was used to screen and identify tentative markers of organic milk from Jersey and Yak. In the targeted strategy, a quick and easy method of ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed to quantify three markers. The peptide of Thr-Ala-Val and D-biotin were determined to be metabolite markers for distinguishing organic and non-organic Jersey milk, whereas trimethylamine N-oxide was determined to be a metabolite marker for distinguishing organic and non-organic Yak milk. These findings provide critical information to facilitate assessments of organic milk authenticity.

Application of multiple stable isotopes to aid identification of the origin of regional and organic animal products in Hesse, Germany

There is an increasing global demand for regional and organic produce. However, the growth of these markets depends on consumers' trust. Thus, novel methods must be developed to aid the verification of the origin of produce. We built on our previous study to identify the geographical origin and production method of animal-derived food products. Thirty-samples of eggs, 99 of milk, 34 of beef, and 62 of pork were collected from different regions in central Germany and analysed for their stable isotopic composition. The analysis followed a single-variate authentification approach using five isotope signatures, δ18O, δ2H, δ13C, δ15N, and δ34S. The best-performing indicators for verification of the geographical origin were δ15N and δ34S for beef; δ18O, δ2H, and δ13C for milk, and δ2H and δ13C for pork. These tracers indicated statistically significant differences among regions with the exception of pork; the results recorded for eggs were inconclusive. It was possible to distinguish between production methods by means of δ15N and δ34S (beef); all five tracers (eggs), and δ13C, δ15N, and δ34S (milk). This study demonstrated how the analysis of stable isotopes can be employed to determine the geographic region of origin and production method of animal-derived products in Germany.

Isotope Fingerprinting as a Backup for Modern Safety and Traceability Systems in the Animal-Derived Food Chain

In recent years, due to the globalization of food trade and certified agro-food products, the authenticity and traceability of food have received increasing attention. As a result, opportunities for fraudulent practices arise, highlighting the need to protect consumers from economic and health damages. In this regard, specific analytical techniques have been optimized and implemented to support the integrity of the food chain, such as those targeting different isotopes and their ratios. This review article explores the scientific progress of the last decade in the study of the isotopic identity card of food of animal origin, provides the reader with an overview of its application, and focuses on whether the combination of isotopes with other markers increases confidence and robustness in food authenticity testing. To this purpose, a total of 135 studies analyzing fish and seafood, meat, eggs, milk, and dairy products, and aiming to examine the relation between isotopic ratios and the geographical provenance, feeding regime, production method, and seasonality were reviewed. Current trends and major research achievements in the field were discussed and commented on in detail, pointing out advantages and drawbacks typically associated with this analytical approach and arguing future improvements and changes that need to be made to recognize it as a standard and validated method for fraud mitigation and safety control in the sector of food of animal origin.

Redefining Quality in Food Supply Chains via the Natural Resource Based View and Convention Theory

This study develops and tests a novel product quality framework for food supply chains (FSCs) that addresses sustainability. Issues including climate change, population growth, and the resources required by industrialized agriculture, as well as changing consumer preferences contribute to concerns about the social, ecological, and economic sustainability of FSCs. FSCs, therefore, need to be adapted to address changing supply and demand characteristics. We integrate the natural resource-based view (NRBV) with convention theory (CT) to develop a new set of quality dimensions. Placing social and ecological considerations within the domain of quality management advances theory in two ways. First, while social and ecological considerations are typically peripheral to business models, this framework allows social responsibility and the natural environment to occupy a central place within FSC operations. Second, the framework reflects the fundamentally socially embedded nature of FSCs, including the geographic, historical, and cultural associations of food quality. We then construct a typology of quality conventions and FSCs. We empirically test the typology using a case study methodology with cases from the United States of America (USA). The analysis explores how firms bundle quality conventions across FSCs for competitive advantage. We also find a set of paths through which FSCs transition via exploitation, exploration and organizational ambidexterity to generate competitive advantage, highlighting tradeoffs that may arise as FSCs evolve. These tradeoffs, which relate to maintaining or adapting quality conventions, are practically important because, if not managed appropriately, may result in lower performance and less sustainable FSCs.

Multivariate analysis for organic milk authentication

To differentiate organic milk (OM) from conventional milk (CM), an orthogonal projection to latent structure-discriminant analysis (OPLS-DA) model was constructed using δ¹³C, δ¹⁵N, δ¹⁸O, 51 elements and 35 fatty acids (FAs) as the variables. So far, most reported studies barely use three or more types of variables, but more variables could avoid one-sidedness and get stabler models. Our multivariate model combines geographical and nutritional parameters and displays better explanatory and predictive abilities (R²X = 0.647, R²Y = 0.962 and Q² = 0.821) than models based on fewer variables for differentiating OM and CM. In particular, δ¹⁵N, Se, δ¹³C, Eu, K and α-Linolenic acid (ALA) are found to be critical parameters for the discrimination of OM. These results show that the multivariate model based on stable isotopes, elements and FAs can be used to identify OM, and can potentially expand the global databases for quality and authenticity of milk.

Dietary homogenization and spatial distributions of carbon, nitrogen, and sulfur isotope ratios in human hair in South Korea

Dietary homogenization has progressed worldwide due to westernization and the globalization of food production systems. We investigated dietary heterogeneity in South Korea by examining the spatial distribution of carbon (C), nitrogen (N), and sulfur (S) isotope ratios using 264 human hair samples. Overall, variation in isotope values was small, indicating low dietary heterogeneity. We detected differences in δ¹³C, δ¹⁵N, and δ³⁴S values between administrative provinces and metropolitan cities; inter-regional differences were typically < 1 ‰. Values of δ³⁴S were significantly lower in hair samples from inland regions relative to those from coastal locations, and a similar pattern was observed in δ¹⁵N values. Understanding geographic variation in δ³⁴S and δ¹⁵N values in human hair is useful for provenancing humans in South Korea.

Determining the geographical origin of milk by multivariate analysis based on stable isotope ratios, elements and fatty acids

To construct a reliable discrimination model for determining milk geographical origin, stable isotope ratios including δ¹³C, δ¹⁵N and δ¹⁸O, 51 elements and 35 fatty acids (FAs) in milk samples from Australia, New Zealand and Austria were detected and analyzed. It is found that all of the stable isotope ratios in the milk samples of Australia are the highest, followed by those of the samples from New Zealand and Austria. In addition, 14 elements and 8 FAs show different contents in the samples of different countries at the significance level of P < 0.05. Based on these results, a multivariate model with good robustness and predictive ability for authenticating milk origin (R²X = 0.693, Q² = 0.854) was successfully constructed. Element contents and stable isotope ratios are more reliable variables for milk origin discrimination and Rb, δ¹⁸O, Tl, Ba, Mo, Sr, δ¹⁵N, Cs, As, Eu, C20:4n6, Sc, C13:0, K, Ca and C16:1n7 are the critical markers in the multivariate model for verifying milk origin.

Prevalence of Milk Fraud in the Chinese Market and its Relationship with Fraud Vulnerabilities in the Chain

This study aimed to assess the prevalence of ultra-high-temperature (UHT) processed milk samples suspected of being adulterated on the Chinese market and, subsequently, relate their geographical origin to the earlier determined fraud vulnerability. A total of 52 UHT milk samples purchased from the Chinese market were measured to detect possible anomalies. The milk compositional features were determined by standardized Fourier transform-infrared spectroscopy, and the detection limits for common milk adulterations were investigated. The results showed that twelve of the analysed milk samples (23%) were suspected of having quality or fraud-related issues, while one sample of these was highly suspected of being adulterated (diluted with water). Proportionally, more suspected samples were determined among milks produced in the Central-Northern and Eastern areas of China than in those from the North-Western and North-Eastern areas, while those from the South were in between. Combining the earlier collected results on fraud vulnerability in the Chinese milk chains, it appears that increased fraud prevalence relates to poorer business relationships and lack of adequate managerial controls. Since very few opportunities and motivations differ consistently across high and low-prevalence areas, primarily the improvement of control measures can help to mitigate food fraud in the Chinese milk supply chains.

Authentication of organic pork and identification of geographical origins of pork in four regions of China by combined analysis of stable isotopes and multi-elements

The purpose of this study was to verify that the organic status of pork purchased in the markets from four different regions of China can be authenticated by the combined analysis of stable isotopes and multiple elements. Four stable isotope ratios (δ¹³C, δ¹⁵N, δ²H and δ¹⁸O) and the concentrations of seven elements (K, Na, Mg, Ca, Fe, Cu and Se) were determined in organic and conventional pork samples from four locations of China. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to analyze stable isotope ratios and multi-element concentrations in pork. Based on the limited database of analytical values, the methodology would be potentially able to confirm whether a sample of pork came from the region and organic status it claimed. These results provide a possibility for authenticity of organic agricultural products from a large scope such as a province even a country.

Dairy farming system markers: The correlation of forage and milk fatty acid profiles from organic, pasture and conventional systems in the Netherlands

The relationships between the fatty acid (FA) composition in forage and milk (F&M) from different dairy systems were investigated. Eighty milk samples and 91 forage samples were collected from 40 farms (19 organic, 11 pasture and 10 conventional) in the Netherlands, during winter and summer. The FA profiles of F&M samples were measured with gas chromatography. The results showed that the F&M of organic farms were significantly differentiated from the F&M of other farms, both in summer and winter. The differences are likely due to the different grazing strategies in summer and different forage composition in winter. The Pearson's correlation results showed the specific relationship between individual FAs in forages and related milk. A PLS-DA model was applied to classify all milks samples, resulting in 87.5% and 83.3% correct classifications of training set and validation set.

Seasonal Variation in Stable Isotope Ratios of Cow Milk in Vilnius Region, Lithuania

Various studies have shown that stable isotope analysis has the potential to verify the geographic origin of foods and drinks. However, stable isotope composition is not always constant in the environment and can even change in the same area. Dairy products are of particular interest as a group of foods that play an important role in feeding the population. The composition of milk is fundamentally dependent on the feeding of the cows, and thereby on a particular environment. To better understand the amount of variation in δ18O, δ13C, and δ15N values in the milk from the same area, we measured stable isotope ratios in cow milk water, artesian water, and precipitation (δ18O) as well as in bulk milk samples (δ13C and δ15N) collected in 2014⁻2016. Different water and food sources were available during the winter (artesian water only and dry grass) and summer (artesian water and fresh grass), and spring and autumn seasons reflected transitional periods. Oxygen stable isotope ratios in milk water were relatively lower in winter and transitional seasons and higher in summer, showing the dependence on the main water source. δ13C values reflected particular food sources. This study shows the applicability of the stable isotope ratio method in linking cow milk to specific environments and reveals the amount of variation in stable isotope ratios in the same area. These results could be valuable for other studies on geographical origin determination of dairy products.

Fatty Acid- and Amino Acid-Specific Isotope Analysis for Accurate Authentication and Traceability in Organic Milk

The present study describes compound-specific δ¹³C and δ¹⁵N analyses of fatty acids and amino acids for improving the accurate authentication of organic milk (OM) against conventional milk (CM) collected in Korea. Most δ¹³C_fatty-acid and δ¹³C_amino-acid values were lower in OM than in CM ( P < 0.05); however, most δ¹⁵N_amino-acid values displayed weak discriminative power for OM authentication. Higher isotopic fractionation was observed in δ¹³C_fatty-acid than in δ¹³C_amino-acid and δ¹⁵N_amino-acid, with fractionation trends differing with individual amino acids. In particular, δ¹³C_{linoleic-acid} of -33.5‰ and δ¹³C_{myristic-acid} of -28‰ were determined to be promising year-round threshold values for Korean OM authentication. The δ¹³C_bulk was highly correlated with δ¹³C_Ala ( r = 0.92) and δ¹³C_{oleic-acid, trans} ( r = 0.77), and strong positive correlations were observed between δ¹³C_Val and δ¹³C_Ile ( r = 0.98) and between δ¹⁵N_Thr and δ¹⁵N_Ser ( r = 0.90). Chemometric modeling for OM authentication produced a high quality model ( R² X = 0.547, R² Y = 0.865, and Q² = 0.689) with reliable chemical markers, notably δ¹³C_{myristic-acid}, δ¹³C_{linoleic-acid}, and δ¹³C_stearic-acid. Furthermore, the models developed for seasonal separation in OM ( Q² = 0.954) and CM ( Q² = 0.791) were of good quality. Our findings, based on compound-specific isotope data, improve the reliability of OM authentication in cases where bulk stable isotope ratio analysis alone is insufficient. They also provide valuable insight into the control of fraudulent OM labeling in Korea, with potential application in other countries.

Carbon and nitrogen stable isotopes in U.S. milk: Insight into production process

RATIONALE

Stable isotope analysis (SIA), a potential method of verifying the geographic origin and production method of dairy products, has not been applied to United States (U.S.) dairy samples on a national scale. To determine the potential of carbon and nitrogen SIA in authenticity assessment of U.S. dairy products, we analyzed a geographically representative collection of conventional milk samples to determine isotopic variations with (1) Purchase Location and (2) Macronutrient Content.

METHODS

A total of 136 milk samples spanning five commercially available varieties (3.25% [i.e., 'whole'], 2%, 1%, 0% [i.e., 'skim'] and 1% chocolate) were collected from randomly selected counties across the U.S. as part of the United States Department of Agriculture's (USDA's) National Food and Nutrient Analysis program. δ¹³ C and δ¹⁵ N values of bulk samples determined via elemental analysis/isotope ratio mass spectrometry (EA/IRMS) were used to assess the contribution of fat content, added sugar content and census-designated region of collection to isotopic variations within the dataset.

RESULTS

There was a negative linear relationship between fat content and δ¹³ C values, with average milk δ¹³ C values decreasing by 0.33‰ for each 8.75% increase in dry weight (1% wet weight) fat content. The average δ¹³ C value of flavored 1% chocolate milk samples, which contain an additional 12 g of added sugar, was 2.05‰ higher than that of 1% unflavored milk (-16.47‰ for chocolate milk vs -18.52‰ for unflavored milk). When controlling for macronutrient content, milk samples collected in West region supermarkets possessed significantly lower δ¹³ C values than samples collected from Midwest, South, and Northeast regions. δ¹⁵ N values did not vary with macronutrient content or region of collection.

CONCLUSIONS

Carbon stable isotope ratios in U.S. milk samples varied with macronutrient content and region of purchase, suggesting that SIA can provide insight into production processes within the U.S. dairy industry, with potential applications in national food adulteration and authentication efforts.

Discrimination of organic milk by stable isotope ratio, vitamin E, and fatty acid profiling combined with multivariate analysis: A case study of monthly and seasonal variation in Korea for 2016-2017

This study examined the monthly and seasonal variations of δ¹³C, δ¹⁵N, fatty acids (FAs), and vitamin E in organic milk (OM) and conventional milk (CM) collected in Korea during 2016-2017, discriminating OM authenticity with chemometric approaches. Compared to CM, the mean δ¹³C and δ¹⁵N values were lower in OM, whereas the mean α-tocopherol and nutritionally desirable FA contents were higher in OM. Furthermore, δ¹³C, δ¹⁵N, and FA contents vary significantly with the season in OM, whereas α-tocopherol does not show a specific seasonal trend in either OM or CM. Chemometric approaches provided reliable chemical markers, notably C18:3n-3, C18:2n-6, and δ¹³C_bulk-milk, for accurate OM discrimination according to sampling season. Our findings elucidate milk nutritional quality issues and also provide valuable insight into the control of fraudulent OM labeling in Korea, with potential application in other countries.

Stable isotope composition of cocoa beans of different geographical origin

The isotopic profile (δ(13) C, δ(15) N, δ(18) O, δ(2) H, δ(34) S) was used to characterise a wide selection of cocoa beans from different renowned production areas (Africa, Asia, Central and South America). The factors most influencing the isotopic signatures of cocoa beans were climate and altitude for δ(13) C and the isotopic composition of precipitation water for δ(18) O and δ(2) H, whereas δ(15) N and δ(34) S were primarily affected by geology and fertilisation practises. Multi-isotopic analysis was shown to be sufficiently effective in determining the geographical origin of cocoa beans, and combining it with Canonical Discriminant Analysis led to more than 80% of samples being correctly reclassified. Copyright © 2016 John Wiley & Sons, Ltd.

Stable carbon and nitrogen isotopes as a potential tool to differentiate pork from organic and conventional systems

BACKGROUND

Isotopic discrimination, dietary composition and feeding regime determine the carbon and nitrogen stable isotope ratios of animals. Accordingly, measurement of the stable isotope ratios of carbon and nitrogen can be a potential method to identify patterns of pork production.

RESULTS

In the current study, we investigated the carbon and nitrogen isotopic ratio in pork from organic and conventional systems. The average carbon and nitrogen isotope ratios for various organic tissues, including hair, blood and defatted meat, were higher than those of conventionally raised ones. The discriminant analysis results based on the combination of carbon and nitrogen isotopic ratios in defatted meat reached a 100% correct classification. Furthermore, the variation in carbon and nitrogen stable isotope ratios of retail organic and conventional pork has been studied over 1 year. The results suggested that organic pork had a higher δ(13) C value than that of the conventional pork in all but three fortnights. Grouping of the δ(15) N data showed that the δ(15) N value in organic pork was higher than that of the conventional one throughout the whole year.

CONCLUSION

The method established in the present study provides a potential detection that can be highly valuable to prevent fraudulent labelling of organic pork. © 2015 Society of Chemical Industry.

Stable Isotope Ratio Analysis for Assessing the Authenticity of Food of Animal Origin

The main elemental constituents (H, C, N, O, and S) of bio-organic material have different stable isotopes (² H, ¹ H; ¹³ C,¹² C; ¹⁵ N,¹⁴ N; ¹⁸ O,¹⁷ O,¹⁶ O; ³⁶ S, ³⁴ S, ³³ S, and ³² S). Isotopic ratios can be measured precisely and accurately using dedicated analytical techniques such as isotope ratio mass spectrometry (IRMS). Analysis of these ratios shows potential for assessing the authenticity of food of animal origin. In this review, IRMS analysis of food of animal origin and variability factors related to stable isotope ratios in animals are described. The study also lists examples of application of stable isotope ratio analysis to meat, dairy products, fish, and shellfish and emphasizes the strengths and weaknesses of the technique. Geographical, climatic, pedological, geological, botanical, and agricultural factors affect the stable isotope ratios (SIR) of bio-elements, and SIR variations are ultimately incorporated into animal tissue through eating, drinking, breathing, and exchange with the environment, being recorded in the resulting foods. SIR analysis was capable of determining geographical origin, animal diet, and the production system (such as organic/conventional or wild/farmed) for pork, beef, lamb, poultry, milk, butter, cheese, fish, and shellfish. In the case of the hard PDO (protected designations of origin) cheeses Grana Padano and Parmigiano Reggiano it is also used in real-life situations to assess the authenticity of grated and shredded cheese on the market.

Free Maillard Reaction Products in Milk Reflect Nutritional Intake of Glycated Proteins and Can Be Used to Distinguish "Organic" and "Conventionally" Produced Milk

Using LC-MS/MS and isotopically labeled standard substances, quantitation of free Maillard reaction products (MRPs), namely, N(ε)-(carboxymethyl)lysine (CML), 5-(hydroxymethyl)-1H-pyrrole-2-carbaldehyde (pyrraline, PYR), N(δ)-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H), and N(ε)-fructosyllysine (FL), in bovine milk was achieved. Considerable variations in the amounts of the individual MRPs were found, most likely as a consequence of the nutritional uptake of glycated proteins. When comparing commercial milk samples labeled as originating from "organic" or "conventional" farming, respectively, significant differences in the content of free PYR (organic milk, 20-300 pmol/mL; conventional milk, 400-1000 pmol/mL) were observed. An analysis of feed samples indicated that rapeseed and sugar beet are the main sources for MRPs in conventional farming. Furthermore, milk of different dairy animals (cow, buffalo, donkey, goat, ewe, mare, camel) as well as for the first time human milk was analyzed for free MRPs. The distribution of their concentrations, with FL and PYR as the most abundant in human milk and with a high individual variability, also points to a nutritional influence. As the components of concentrated feed do not belong to the natural food sources of ruminants and equidae, free MRPs in milk might serve as indicators for an adequate animal feeding in near-natural farming and can be suitable parameters to distinguish between an "organic" and "conventional" production method of milk.

Ginseng authenticity testing by measuring carbon, nitrogen, and sulfur stable isotope compositions that differ based on cultivation land and organic fertilizer type

Background

The natural ratios of carbon (C), nitrogen (N), and sulfur (S) stable isotopes can be varied in some specific living organisms owing to various isotopic fractionation processes in nature. Therefore, the analysis of C, N, and S stable isotope ratios in ginseng can provide a feasible method for determining ginseng authenticity depending on the cultivation land and type of fertilizer.

Methods

C, N, and S stable isotope composition in 6-yr-old ginseng roots (Jagyeongjong variety) was measured by isotope ratio mass spectrometry.

Results

The type of cultivation land and organic fertilizers affected the C, N, and S stable isotope ratio in ginseng (p < 0.05). The δ¹⁵N_AIR and δ³⁴S_VCDT values in ginseng roots more significantly discriminated the cultivation land and type of organic fertilizers in ginseng cultivation than the δ¹³C_VPDB value. The combination of δ¹³C_VPDB, δ¹⁵N_AIR, or δ³⁴S_VCDT in ginseng, except the combination δ¹³C_VPDB–³⁴S_VCDT, showed a better discrimination depending on soil type or fertilizer type.

Conclusion

This case study provides preliminary results about the variation of C, N, and S isotope composition in ginseng according to the cultivation soil type and organic fertilizer type. Hence, our findings are potentially applicable to evaluate ginseng authenticity depending on cultivation conditions.

Effect of baking and fermentation on the stable carbon and nitrogen isotope ratios of grain-based food

RATIONALE

Isotope ratio mass spectrometry (IRMS) is used extensively to reconstruct general attributes of prehistoric and modern diets in both humans and animals. In order to apply these methods to the accurate determination of specific intakes of foods/nutrients of interest, the isotopic signature of individually consumed foods must be constrained. For example, 86% of the calories consumed in the USA are derived from processed and prepared foods, but the relationship between the stable isotope composition of raw ingredients and the resulting products has not been characterized.

METHODS

To examine the effect of common cooking techniques on the stable isotope composition of grain-based food items, we prepared yeast buns and sugar cookies from standardized recipes and measured bulk δ(13) C and δ(15) N values of samples collected throughout a 75 min fermentation process (buns) and before and after baking at 190°C (buns and cookies). Simple isotope mixing models were used to determine if the isotopic signatures of 13 multi-ingredient foods could be estimated from the isotopic signatures of their constituent raw ingredients.

RESULTS

No variations in δ(13) C or δ(15) N values were detected between pre- and post-baked yeast buns (pre: -24.78‰/2.61‰, post: -24.75‰/2.74‰), beet-sugar cookies (pre: -24.48‰/3.84‰, post: -24.47‰/3.57‰), and cane-sugar cookies (pre: -19.07‰/2.97‰, post: -19.02‰/3.21‰), or throughout a 75 min fermentation process in yeast buns. Using isotopic mass balance equations, the δ(13) C/δ(15) N values of multi-ingredient foods were estimated from the isotopic composition of constituent raw ingredients to within 0.14 ± 0.13‰/0.24 ± 0.17‰ for gravimetrically measured recipes and 0.40 ± 0.38‰/0.58 ± 0.53‰ for volumetrically measured recipes.

CONCLUSIONS

Two common food preparation techniques, baking and fermentation, do not substantially affect the carbon or nitrogen isotopic signature of grain-based foods. Mass-balance equations can be used to accurately estimate the isotopic signature of multi-ingredient food items for which quantitative ingredient information is available.