Flavor Authentication Studies of α-Ionone, β-Ionone, and α-Ionol from Various Sources

Abstract

In addition to the already available information on the authenticity of alpha- (1) and beta-ionone (2) from plant tissues, there is an interest in the stable isotope data of 1 and 2 available by synthesis from citral and acetone, as European Union regulations, in contrast to the United States and other countries, do not allow a product to be declared as 'natural' that has been chemically synthesized (e.g., by using a natural catalyst) from natural educts. Analyses performed by on-line capillary gas chromatography-isotope ratio mass spectrometry in the combustion and pyrolysis modes (HRGC-C/P-IRMS) as well as by elemental analyzers (EA-C/P-IRMS) measuring delta(13)C(V)-PDB and delta(2)H(V)-SMOW values provide for the first time isotope data of such 'natural' 1 and 2 as well as of synthetic and 'ex plant' alpha-ionol (3). The isotope data recorded for synthesized 1 and 2 reflected the influence of the origin of the used citral, whereas that of acetone was less remarkable. For instance, 'natural' 1 ex citral from lemongrass showed, as expected for a C4 plant, an enriched delta(13)C(V)-PDB value of -18.5 per thousand. In addition, the use of synthetic citral resulted in an enriched delta(2)H(V)-SMOW value of -43 per thousand, whereas with citral ex Litsea cubeba and ex lemongrass values of -242 and -232 per thousand, respectively, were recorded. IRMS analyses of 'natural' 2 revealed delta(13)C(V)-PDB and delta(2)H(V)-SMOW values that were nearly identical to that recorded for 'natural' 1. As to both 1 and 2, variations of synthesis conditions led to distinct changes in the delta(13)C(V)-PDB but not the delta(2)H(V)-SMOW values. Synthetic 3 showed delta(13)C(V)-PDB and delta(2)H(V)-SMOW values of -24.5 and -184 per thousand, respectively. These data differed from those found in raspberry fruit under study (n = 8), that is, ranging from -33.6 to -36.6 per thousand for delta(13)C(V)-PDB and from -200 to -225 per thousand for delta(2)H(V)-SMOW. The values determined additionally for 1 and 2 in raspberry fruit samples ranged from -30.3 to -35.1 per thousand and from -176 to -221 per thousand for delta(13)C(V)-PDB and delta(2)H(V)-SMOW, respectively, and thus corresponded to the already known literature information.

Multi-factorialin vivostable isotope fractionation: causes, correlations, consequences and applications

“…This is obviously the case with a new class of persistent biomarkers: lipids as n-alkanes, terpenoids, hopanoids and phytanes [121]. They preserve in various sediments over geological periods the material composition and relative range of δ 2 H values as known from present representatives in agreement with their origin and biosynthesis [273,302,303]. Therefore, they can be used as reliable indicators for ancient environmental conditions (local climate, precipitation and salinity) and ecosystems (composition and variety of flora).…”

Gas Chromatography‐Combustion‐Isotope Ratio Mass Spectrometry for Traceability and Authenticity in Foods and Beverages

“…Prunus fruits such as peaches, apricots, and nectarines were analyzed by Tamura and others () for the isotopic ratios of γ‐decalactone and δ‐decalactone (δ 13 C ranges of γ‐decalactone and δ‐decalactone for fruits: −34.0‰ to −38.4‰; “natural”: −27.7‰ to −30.1‰; and synthetic: −27.4‰ to −28.3‰ and δ 2 H ranges of both compounds for fruits: −160‰ to −228‰; “natural”: −185‰ to −286‰; and synthetic: −151‰ to −184‰). Berries also have been subjected to isotope analysis, for example, del Mar Caja and others () analyzed raspberry for α‐ionone, β‐ionone, and α‐ionol (δ 13 C ranges of α‐ionone, β‐ionone, and α‐ionol for fruits: −30.3‰ to −36.6‰; “natural”: −9.1‰ to −28.0‰; and synthetic: −24.5‰ to −29.0‰ and δ 2 H ranges of both compounds for fruits: −176‰ to −225‰; “natural”: −43‰ to −257‰; and synthetic: −26‰ to −184‰). Both studies were able to differentiate between fruit, “natural,” and synthetic‐derived compounds, proving that the GC‐C/P‐IRMS is useful for authenticity assessments.…”

Construction of IsoVoc Database for the Authentication of Natural Flavours

“…Much effort has also gone into developing isotopic methods to detect adulteration of natural products with synthetic compounds. Among them, gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) seems to be the most specific and sophisticated method that can discriminate between natural and synthetic aromas based on the isotopic values of selected volatile organic compounds, VOCs [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. The use of GC-C-IRMS is the subject of a review by van Leeuwen et al [ 8 ] and a paper by Strojnik et al [ 26 ] in which the authors emphasise the importance of the relevant analytical conditions to obtain precise isotopic ratios.…”

“…Articles on determining the authenticity of fruit volatile organic compounds based on GC-C-IRMS are summarised in Appendix A ( Table A1 ). These studies cover, for example, raspberry [ 10 , 13 , 18 , 19 , 27 ], peach [ 7 , 11 , 23 , 25 ], strawberry [ 7 , 8 , 20 ], apple [ 16 , 25 , 28 ], nectarine [ 11 , 23 , 25 ], pineapple [ 7 , 9 ], and orange [ 15 , 25 ]. Many aromatic characteristics are shared between different fruits.…”