Abstract
A fast and simple method for authenticating raspberry flavors from food products was developed. The two enantiomers of the compound (E)‐α‐ionone from raspberry flavor were separated on a chiral gas chromatographic column. Based on the ratio of these two enantiomers, the naturalness of a raspberry flavor can be evaluated due to the fact that a natural flavor will consist almost exclusively of the R enantiomer, while a chemical synthesis of the same compound will result in a racemic mixture. Twenty‐seven food products containing raspberry flavors where investigated using SPME‐chiral‐GC‐MS. We found raspberry jam, dried raspberries, and sodas declared to contain natural aroma all contained almost only R‐(E)‐α‐ionone supporting the content of natural raspberry aroma. Six out of eight sweets tested did not indicate a content of natural aroma on the labeling which was in agreement with the almost equal distribution of the R and S isomer. Two products were labeled to contain natural raspberry flavors but were found to contain almost equal amounts of both enantiomers indicating a presence of synthetic raspberry flavors only. Additionally, two products that were labeled to contain both raspberry juice and flavor showed equal amounts of both enantiomers, indicating the presence of synthetic flavor.
Highlights
Authenticity of food products is often used as a parameter of quality in marketing
SPME fibers: SPME fibers were purchased from Supelco, (Supelco, USA), all coated on a fused silica fiber and with a length of 1cm; divinylbenzene (DVB)/polydimethylsiloxane (PDMS) 65μm coating, carboxen (CAR)/(PDMS) 75μm coating and DVB/CAR/PDMS 50μm DVB and 30μm CAR on PDMS coating
SPME-chiral-GC-MS method: The SPME fibers were used for extracting aroma compounds from raspberries and subsequent analysis using automated headspace solid phase micro extraction (HS-SPME) using a GC-Combi PAL (CTC Analytical, Zwingen, Switzerland) on an Agilent 6890 gas chromatograph (GC) (Agilent Technologies, Inc., Wilmington, Germany) equipped with an Agilent 5979 Mass Selective Detector
Summary
Authenticity of food products is often used as a parameter of quality in marketing. Food products containing only natural ingredients are preferred by many consumers who are willing to pay a higher price for such products. Some of the flavoring substances are chiral and the enantiomeric composition in raspberry extracts was characterized by chiral GC-MS, α-ionone occurs mainly in the R-form (97-100%) whereas δ-octalactone, δ-decalactone and terpinen-4-ol occurs mainly in the S-form (80-100%) (Malowicki et al 2008a and b). For all fruits there seemed to be a preponderance of the R-form of the longer chained γ-lactones > C8 whereas for the shorter chained γ-lactones some fruits had preponderance of the R-form, some of the S-form and some hardly showed enantiomeric excess In both orange flowers and unifloral orange honey the enantiomeric composition of linalool was 87-91% of the (+) form and 9- 13% of the (-) form indicating the usefulness of chiral analysis in the authenticity assessment of unifloral honey (Verzera et al, 2014)
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