Online Laboratory Magazine


Sensor detects mouldy or adulterated spices

What does a spice like pepper or paprika smell like if it is contaminated with mould or how does one determine whether a spice has been adulterated, for example, with mustard flour? It is difficult to determine, but experienced and trained noses can distinguish it. However, can these estimates be verified? Fortunately a mobile spice sensor for which the BAM Federal Institute for Materials Research and Testing has developed reference samples, will soon be provided to help with quality control and product safety.

Certain substances are responsible for the intense aroma in spices. The smell of pepper or paprika can be recognised by specific flavour substances such as terpenes. Terpenes are hydrocarbons, which mainly occur in plants, and also constitute the main ingredient of essential oils. BAM has developed a small emission chamber which can hold the spice to study such volatile ingredients. "As little as 50 milligrams of pepper or two grams of paprika are enough to carry out a measurement," says Carlo Tiebe of BAM. The air in the one-litre emission chamber is fully saturated by the aroma within half an hour. Synthetic air flows into the chamber, picks up the flavour substances and transfers them to the spice sensor connected to the emission chamber. The measurements at BAM have been carried out using this new sensor. The Berlin firm Environics-IUT GmbH has developed the device, which is now available as a prototype. A novel ion mobility spectrometer is used with a chromatographic column (GC-IMS), and this can be used in a mobile fashion.

Spices are already being tested for their quality, however, the tests are relatively expensive, are currently only available in the laboratory and require specially trained personnel. Therefore, one usually relies on estimates by testers with very sensitive noses. There are of course standards for this process, which is called olfactometry, but, "the new reference samples and the device should improve transparency and objectivity in the production of spice blends" says chemist Tiebe. For example, spice manufacturers can easily check whether or not the spice has been properly stored or transported. Also, they can now more easily find out if the paprika spice has been adulterated by ten percent of the cheaper mustard flour. A glance at the device's display will suffice. Of course, this is much harder when checking an odour sample contaminated with the odourless mustard flour, which is very difficult to detect by smell. The research project will run until June 2014 and is sponsored by the Federal Ministry of Economics and Technology (BMWi) with funds from the "Central Innovation Programme for SMEs".

Source: Federal Institute for Materials Research and Testing (BAM)