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Isolab GmbH - Laboratorium für Stabilisotopenanalytik

Stable isotopes analysis for the determination of origin and authenticity of

Food
Beverages
Flavoring
Fodder
Wood and Synthesis Chemicals
As well as Forensic and
Archaeological samples

The origin and authenticity of our food determine its quality and price, and consumers expect these two factors to match. Determining the ratios of stable isotopes of biomass, water or minerals from food can ensure that consumers aren't buying freshly squeezed fruit juice from fruit juice concentrate, Bordeaux wine from Romania, Parmesan cheese from Bavarian milk, organic eggs from battery hens or German beef from Argentina.

How to identify false advertisting

The origin and authenticity of our food determine its quality and price, and consumers expect these two factors to match. Determining the ratios of stable isotopes of biomass, water or minerals from food can ensure that consumers aren't buying freshly squeezed fruit juice from fruit juice concentrate, Bordeaux wine from Romania, Parmesan cheese from Bavarian milk, organic eggs from battery hens or German beef from Argentina.

Kindly approved by: dmz 21 18-23 (2003)

The origin and authenticity of our food determine its quality and price, and consumers expect these two factors to match. Determining the ratios of stable isotopes of biomass, water or minerals from food can ensure that consumers aren't buying freshly squeezed fruit juice from fruit juice concentrate, Bordeaux wine from Romania, Parmesan cheese from Bavarian milk, organic eggs from battery hens or German beef from Argentina.

δ13C[‰]V-PDB= links (13C/12C)PROBE  -1 rechts  *1000
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(13C/12C)V-PDB

δ13C-values ([‰] VPDB) of biomass - Photosynthesis type of plants

The carbon isotope effect on the primary reaction of CO2 assimilation is responsible for the δ13C value of biomass. In so-called C3 plants, most of our native plants, the δ13C value is between -30 and -25‰, in C4 plants (corn, sugarcane, millet) between -14 and -11‰, and in CAM (crassulacean acid metabolism) plants (pineapple, vanilla) between -21 and -18‰. Based on this, the proportion of C4 material in plant biomass or in animal feed can be calculated. The respective range given is determined, among other factors, by climatic and plant anatomical characteristics and includes corresponding information. Animal products reflect the animals' diet with a trophic level effect of approximately +1.5‰.

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δ15N-values ([‰] AIR) of biomass - Nitrogen sources

The primary N-reservoir for organically bound nitrogen is atmospheric nitrogen with δ15N = 0‰. It serves as an immediate nitrogen source during nitrogen assimilation by legumes (used in green manure) and for technically produced ammonia and nitrate (used in mineral fertilization). Nitrification, denitrification, and ammonia evaporation lead to 15N enrichment in the unreacted portions of the respective starting materials. Organic fertilizers and soil-bound nitrogen are also generally relatively enriched in 15N; this is among the reasons why products from organic farming typically have a higher δ15N value than conventionally produced ones. The trophic level effect for animal products is approximately +2‰ per level.

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δ2H- and δ18O-values ([‰]VSMOW) of biomass - Climate and water cycle

Water is a fundamental component of most foods; moreover, it serves as a precursor for organically bound hydrogen and oxygen. Due to the higher vapor pressure of "light" water molecules (1H1H16O), these accumulate in the vapor, while the "heavy" water molecules (1H2H16O, 1H1H18O) accumulate in the condensate. Consequently, precipitation and groundwater become lighter the further they are from the ocean (continental effect) and the higher they occur (altitude effect). Additionally, local climate and plant anatomical factors determine plant water evaporation, influencing the H and O isotopic characteristics of leaf water and ultimately plant biomass. In animal biomass, the δ18O values of water are influenced by those of drinking water, food, and metabolic water. The δ2H values of major fractions from plant and animal tissues (carbohydrates, proteins, fats) differ characteristically due to metabolic hydrogen isotopic fractionation.

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δ34S-([‰]VCDT) and δ87Sr-values of biomass - local geological features

δ34S-([‰]V-CDT) and δ87Sr values of biomass are due to the isotopic characteristics of the local primary sources. In the case of sulphur, in addition to soil SO42-, SO42- from sea aerosol (sea spray) near the sea and SO2 from combustion processes near industrial plants and highways are added. The allocation therefore requires a corresponding cadastre or comparative values. The same applies to 87Sr and to isotopes of (anthropogenically introduced) heavy metals (Pb and others). Strontium is the most important indicator for the geographical determination of origin.

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