Saving time, money and reputation: aromaLAB talks fighting off-flavours

By Katy Askew contact

- Last updated on GMT

From compound to cause: aromaLAB traces off-flavours ©iStock
From compound to cause: aromaLAB traces off-flavours ©iStock
Scientists at aromaLAB specialise in tracking off-flavours to their chemical compounds. This enables food makers to see exactly what went wrong and take corrective action.

No brand wants to deal with the reputational fallout of delivering sub-par products. And that means that when an off-flavour is found in a packaged food or beverage, it is vital to find out what went wrong and fix it - fast.

Off-flavours are taints in food products caused by the presence of undesirable flavour compounds. In many cases, traces of a single compound can spoil the flavour of the product to the point where it is no longer edible.

Examples of off-flavours include 2,4,6-trichloroanisole (mouldy off-flavour) in wine, skatole and p-cresol (fecal, horsestable-like off-flavor) in white pepper, methional (“sunlight” flavour) in milk or geosmin (earthy off-flavour) in cocoa products.

The problem is relatively widespread, according to aromaLAB researcher Dr. Veronika Greger. “It is a pretty big problem, given the multitude of samples with off-flavours we've analysed over the last ten years,”​ she told FoodNavigator.

“In some cases, the companies detect the problem before the product goes on sale during internal quality control. But often they are not aware that something is wrong with the flavour of their product until customers complain – these are certainly the more critical cases.”

Help is at hand

When something has gone wrong, it is vital to figure out what and why. This is where experts like German-based aromaLAB can step in.

“We think it is rather important to identify the cause of the off-flavour on a molecular level (i.e. to identify the compounds) because in many cases it is then possible to guess the reason for the formation of a certain compound or how it found its way into the product.

“Some compounds are typically formed during heating (or overheating) the product, some are the result of microbial activity, others are formed during exposure of the product to light. The possibilities are manifold. However, it is not always possible to explain the origin of the off-flavour, but the success rate is higher once the compound is known.”

aromaLAB “usually”​ identifies the compounds using Gas chromatography/Olfactometry (GC/O), although Dr. Greger said sometimes the sensory evaluation of the sample gives the “first hint”​ of what the problem is.

GC/O means that a solvent extract is prepared from the sample and analysed via gas chromatography with simultaneous flame-ionisation and olfactometric detection. The carrier gas effluent is split in half and one part of the effluent is led to the flame ionisation detector while the other part is led to a “sniffing port”​, where the human nose is used as a detector.

“By sniffing the carrier gas effluent, a trained analyst is able to detect the odour-active compounds in the sample. These compounds are subsequently identified on the basis of odour quality and retention time by comparison with compounds from an in-house database,”​ Dr. Greger revealed.

If a compound causing an off-flavour is identified, it is then quantified using a stable-isotope labelled internal standard (13C- or 2H-labelled) by means of Gas chromatography/Mass spectrometry (GC/MS).

The detective work begins

Once the compound is identified, aromaLAB works with its clients to figure out what is responsible for the formation of the off flavour in either the processing, packing or distribution process.

“For example, not long ago, we had a water sample with a sour, musty off-note. After we had identified decanoic acid as a possible source of the off-flavour, we asked the client (the producer of the mineral water) about his thoughts on this result. He told us that they were using a cleaning agent containing decanol and that the decanoic acid (which is formed from decanol by oxidation with atmospheric oxygen) is most likely a result of the use of this cleaning agent.”

Dr Greger said that aromaLAB’s expertise is “helpful in terms of time, money and reputation”​. She estimates that the group is successful in hunting down the cause of off-flavours in around 90% of the cases it works on.

Related topics: Food safety, Food Safety & Quality

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