NMR analysis helps identify saffron adulteration

Saffron is so expensive it is little wonder that criminals are tempted to cut the spice with adulterants to bulk it up.

The addition to your kitchen spice rack is so expensive - at several thousand dollars per 100g - that safflower, turmeric, gardenia and the stamens of the Crocus sativus plant from which saffron is harvested are all used to boost profit margins by unscrupulous dealers.

Everyone know adulteration is rife, detecting the activity is actually pretty hard, particularly for the powdered version of the spice, and for this reason the best quality saffron is usually sold in filaments.

Now, researchers from Greece and Italy have developed a laboratory technique - based on nuclear magnetic resonance (NMR) spectroscopy and chemometrics - that should make it easier to spot the fraud, regardless of the form in which the spice is presented.

The scientists used a Bruker Biospin AVANCE 600 spectrometer to analyse 10 samples of Greek saffron and produce a snapshot or 'fingerprint' of the metabolites present that could be compared against a representative, unadulterated sample of the spice.

The NMR technique was able to identify when safflower, gardenia, C sativus stamens and turmeric was present in the sample at a minimum level of 20 per cent by weight.

Importantly, the approach required only a tiny sample of the spice, was quick and easy to carry out and seemed to be very reproducible, which means it should be suitable for screening large quantities of saffron.

"The detection of commercial frauds in saffron is a challenging task since changes in physical, chemical or organoleptic properties are not always easily identifiable," say the authors, who have published their findings in the journal Food Chemistry.

Using the NMR-based approach "adulteration of saffron could be easily evaluated for each plant …bulking agent," they write, adding that this is thought to be the first time that the technique has been evaluated in this setting.

With a bit more work, it could be adapted for use with a broader range of saffron grades coming from multiple areas of the world, they conclude.

Image courtesy of Shutterstock / marilyn barbone