Detection of Added Beet Sugar in Concentrated and Single Strength Fruit Juices by Deuterium Nuclear Magnetic Resonance (SNIF-NMR Method): Collaborative Study

Abstract

A collaborative study of the site-specific natural isotope fractionation-nuclear magnetic resonance (SNIF-NMR) method for detecting added beet sugar in fruit juices is reported. This method is complementary to the stable carbon isotope ratio analysis (SCIRA) (AOAC Official Methods 981.09 and 982.21), which can detect sugars derived from plants exhibiting C4 metabolism (corn and sugarcane). It is based on the fact that the deuterium content at specific positions of the sugar molecules is higher in fruit sugars than in beet sugar. The fruit juices are fermented, and the alcohol is distilled with a quantitative yield and analyzed with a highfield NMR spectrometer fitted with a deuterium probe and fluorine lock. The proportion of ethanol molecules monodeuterated on the methyl site is recorded. This parameter (D/H)i is lowered when beet sugar is added to a fruit juice or concentrate. The precision of that method for measuring (D/H)i was observed to be similar to that of other isotope ratio methods: sr values ranged from 0.19 to 0.25 ppm and SR values varied between 0.21 and 0.37 ppm. An excellent correlation was observed between the percentage of added beet sugar and the (D/H)i isotope ratio measured in this collaborative study. Consequently, all samples in which beet sugar was added were found to have a (D/H)i isotope ratio significantly below the normal value for authentic juice or concentrate of that fruit. The SNIF-NMR method for detection of added beet sugar in fruit juices has been adopted by AOAC INTERNATIONAL.

Combination of 13C and 2H SNIF‐NMR isotopic fingerprints of vanillin to control its precursors

“…A clear distinction between vanillin origins was achieved considering the sources used at that time (synthetic versus natural ex‐bean samples). As a result, the method was approved as official method by the Association of Official Analytical Chemists (AOAC 2006.05); however, because deuterium atoms have a low natural abundance, the quantity of pure vanillin necessary for the analysis is approximately 1 g, and the acquisition with an adequate signal‐to‐noise ratio (SNR) takes around 15 hours on common spectrometers equipped with a specific room‐temperature probe for three spectra. This method is therefore expensive in terms of preparation time and instrumental time, and this excludes the possibility to work on finished products (e.g.…”

Characterization of farmed and wild salmon (Salmo salar) by a combined use of compositional and isotopic analyses

“…The SNIF-NMR technique was developed in the early 1980s (6) and was applied to detect adulteration of wine (7,8). Today this method has been adopted as an official European method for authentication of wines (9) and as an AOAC approved technique for the control of sugar addition in fruit juices (10). Isotopic fractionation studies of lipids have been mainly carried out by 13 C IRMS (11,12), and several SNIF-NMR studies have been devoted to plant lipids (13) and to olive oils (14)(15)(16).…”

Measurement of Adjuncts in Hard Ciders Obtainable in the United States Using Carbon Isotopes

“…The sweeteners used in these ciders are likely derived from beet sugar rather than corn or cane sugar. The addition of beet sugar can be detected utilizing the SNIF-NMR method, as has been done for fruit juices, maple syrup, and still wines. − This represents an avenue of future work for detecting beet sugar as an adjunct in hard ciders. In the case of the Strongbow Honey and Apple, it likely contains honey as the name implies, though it is not listed as an ingredient.…”