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In common with most jurisdictions, India has regulatory analytical criteria for authentic honey.  This includes various stable isotope ratios.

In this study (open access) the researchers set out to construct an analytical database of fully traceable authentic honeys in order to verify the criteria set by the Food Safety and Standards Authority of India.

They collected 98 authentic samples (covering 19 botanical sources, 42% multifloral and 58% monofloral).  They covered 17 states and provinces.  Sample were from collection centres of the All-India Coordinated Research Project on Honey Bees and Pollinators (AICRP, HB&P), under the auspices of the Indian Council of Agricultural Research (ICAR).   In addition, beekeepers registered with the National Bee Board (NBB) were also identified for sample collection. All samples were fully traceable.

The researchers generated a database of stable carbon isotope ratios (¹³C/¹²C) by Elemental Analyzer/Liquid Chromatography–Isotopic Ratio Mass Spectrometry (EA/LC-IRMS). The samples were analyzed for the parameters δ¹³C_Honey(δ¹³C_H), δ¹³C_Protein(δ¹³C_P), δ¹³C individual sugars, ∆δ¹³C_{Protein-Honey}(δ¹³C_P-H), C4 sugar, ∆δ¹³C_{Fructose-Glucose}(δ¹³C_Fru-Glu), ∆δ¹³C_max, and foreign oligosaccharides as per the official methods of analysis of the Association of Official Analytical Chemists (AOAC 998.12) and the FSSAI.

The results were evaluated against the published literature and Indian regulatory criteria for authentic honey. The δ¹³C value for honey (δ¹³C_H) ranged from −22.07 to −29.02‰. It was found that 94% of samples met the criteria for Δδ¹³C_P-H (≥−1.0‰), Δδ¹³C_Fru-Glu (±1.0‰), and C4 sugar content (7% maximum), with negative C4 sugar values treated as 0% as prescribed by the AOAC method.  86% of samples met the accepted foreign oligosaccharide criteria (maximum 0.7% peak area).

They conclude that the data of this study provide scientific backing for these four parameters as per the FSSAI regulation. However, the non-compliance of a high number (47%) of authentic honey samples for Δδ¹³C_max (±2.1‰) compels further systematic investigation with a special focus on bee feeding practices. Further, they found that honey samples with a Δδ¹³C_P-H greater than +1‰ and a C4 sugar content more negative than −7% also did not comply with the Δδ¹³C_max criteria. They suggest that Δδ¹³C_P-H values (>+1‰ equivalent to C4 sugar < −7%) could be an indicator of C3 adulteration to some extent.

This review (open access) presents a comprehensive summary of the principles and recent advancements in the application of stable isotope techniques for authenticity assessment. It examines their use in detecting fraud (e.g., identifying edible alcohol, exogenous water, carbonylation, and trace compounds), vintage identification, and geographical origin determination across various alcoholic beverages, with a particular focus on wine, Chinese baijiu, and beer.   It cites over 100 publications from the past 15 years.

The authors conclude that stable isotope analysis is a powerful tool for verifying the authenticity of alcoholic beverages, offering effective solutions to combat counterfeiting, mislabeling, and adulteration. They recommend that future studies should focus on understanding the ecological, biological, and hydrometeorological factors influencing isotope signatures and develop advanced multi-isotope and chemometric approaches to improve reliability. Expanding global databases and integrating emerging technologies such as artificial intelligence (AI) and machine learning will further enhance the effectiveness and accessibility of stable isotope techniques, ensuring safer and higher-quality alcoholic beverages for consumers worldwide.

Photo by Ibrahim Boran on Unsplash

This study (open access) examined how variations in δ²H and δ¹⁸O values of cooking water affect the isotopic fingerprint of noodles with different gluten-to-starch formulations.

Eight differently formulated noodles were boiled using waters with six distinct isotopic compositions ranging from of −160‰ to +50‰ for δ²H and from −22.9‰ to +99.9‰ for δ¹⁸O, respectively.

It was found that formulation and water isotopic composition significantly affected the δ²H in cooked noodles. Additionally, the δ²H values of noodles changed with the isotopic signatures of the cooking water. Conversely, δ¹⁸O in the noodles remained stable despite boiling processing and was also not changed by the water's isotopic signature.

The authors derived an equation for determining the exchange factor (f(H)ex) between noodles and cooking water. The fraction of hydrogen atoms in different noodles for exchange was highest at 19.3% in noodles with the formulation of 45:55(gluten-to-starch) and the lowest at 11.1% in noodles with 100% gluten.

The authors conclude that cooking water systematically alters the isotopic signatures of noodles, underscoring the necessity of considering this type of effect in food authentication and traceability practices.

Photo by M. W on Unsplash

There is a price premium for tomato sauce labelled as “natural” or “no artificial additives”.  Citric acid (E330) is a common component of tomato sauces, and the cheapest form is biosynthetic (i.e. it is not “natural”).  There is therefore an incentive for deliberate misrepresentation on the label, and a consequential need for test verification methods as to whether the citric acid is “natural”.  Current reference specifications (e.g. AIJN) do not include tomato sauce.

In this conference presentation (open access) the authors report the successful use of Stable Isotope Ratio Analysis to discriminate the botanical source of the citric acid in tomato sauce  Biosynthesised citric acid is from cane or corn feedstock (C4 plants) whereas inherent tomato citric acid is C3.  The researchers established threshold values for citric acid carbon isotope ratios from authentic “natural” tomato sauces and used these to test a range of products on the market.

Photo by sentidos humanos on Unsplash

Isotope ratio data are increasingly used in a variety of fields including, ecology, marine sciences, earth and geosciences, forensic science, hydrology, medicine, food (including food authenticity and origin), and climate science.
 
Over the years, there have also been changes to guidelines for measurement methods, calibration conventions and even to international measurement standards that form the base of the traceability chain for isotope delta values for H, C, N, O and S.
 
It is impossible to combine isotope ratio data from a variety of sources unless the data are accompanied by a clear description of traceability and other method details.

The UK National Measurement Laboratory at LGC was part of an international group that compiled the IUPAC Technical Report presenting minimum requirements for reporting isotope ratio data, covering analytical procedure, traceability, data processing and uncertainty evaluation.

This report will help in the standardisation of methods that involve the measurement of stable isotopes.

Read the IUPAC Technical Report on minimum requirements for publishing hydrogen, carbon, nitrogen, oxygen and sulfur stable-isotope delta results.