nmr (5)

Tesco's withdrawal of its own-label honey comes after an investigation by Richmond Council  Trading Standards. Honey was sent for analysis by NMR,which gave results that it was adulterated with exogenous sugar syrups. Tesco has temporarily taken the honey off the shelves for further examination, but insists the product is "100% pure, natural and can be directly traced back to the beekeeper".

3742110317?profile=RESIZE_710x Read the BBC article

Read more…

This review by Polish researchers reviews the use of spectroscopic methods in testing the authenticity of some selected herbs and spices. The review covers the spectroscopic techniques - IR, NMR, UV in combination with advanced statistical methods (PCA, CA) to confirm either the origin of the product or  distinguishes the herbs or spices from any adulterating ingredients. 

3686348872?profile=RESIZE_710x Read the abstract here

Read more…

Nuclear magnetic resonance (NMR) spectroscopy has increasingly been applied in the field of food authenticitation. Its instrumental variability is very low so that it is possible to compile large databases of authentic spectra. This review discusses the application of NMR for authenticating honey, beer and spices. For honey, it is possible to verify the botanical origin and exclude adulteration with sugars. In beer analysis, it is possible to distinguish between major beer types and to detect the geographical origin of beer. In spice analysis, NMR allows to detect crude adulterations (e.g. of saffron) or quantify marker ingredients such as essential oils.

                 Read the full review at: NMR authentication

Read more…

16-O-methylcafestol (16-OMC)  is used as a marker for non-Arabica coffees (Robusta coffee). UK researchers have analysed lipophilic extracts from 30 authentic roasted Arabica coffees by high-field and low-field proton NMR spectroscopy, and found a small marker peak, which has subsequently been identified as 16-OMC and 16-O-methylkahweol.  This is the first time these markers have been found in Arabica coffee, and previously thought to only exist in non-Arabica coffee. However, the level of 16-OMC in Arabica coffee is very low and much higher in Robusta coffee. Therefore, using low-field NMR, Robusta in Arabica could be detected at levels of the order of 1–2% w/w. A surveillance study of retail purchased “100% Arabica” coffees found that 6 out of 60 samples displayed the marker signal to a degree commensurate with adulteration at levels of 3–30% w/w. 

Read the full article at: Arabica coffee authenticity

Read more…

Researchers applying a multi-step approach using HPLC, UV–Vis, FT-IR and NMR analyses, uncovered a new type of adulteration of a commercial product labelled as “saffron”, and sold packed in powder form in a major consuming country.  Applying the four methods and NMR data from in-house databases, they uncovered a  “tailor-made” case of 100% substitution of saffron by a mixture of exogenous chemical compounds in such a way that the commercial product would approximately mimic not only the appearance of saffron but also its UV–Vis spectrum and specific absorbance values. The findings indicated a sophisticated practice, including total substitution of saffron constituents by tartrazine and sunset yellow along with propane-1,2-diol, propan-2-ol and acylglycerols, probably as emulsifier agents. 

Read the abstract at: Multi-step approach uncovers saffron fraud

Read more…