By Rob Levermore - 29 April 2019

What is ‘taint’ in food and drink?

Flavour is an important component of food quality. Off-flavours are generally defined as unpleasant odours or tastes due to natural deterioration of the food. Taints, on the other hand, are usually regarded as unpleasant odours or tastes resulting from contamination of a food by one or more extraneous chemicals.

Understanding flavour, off-flavours and taints – including their formation and how they change during processing and storage – is vital when it comes to product quality, product development, in process control and for troubleshooting.

Typical taint descriptions include, for example, 'antiseptic', 'musty', 'rancid' and 'petrol'. A manufacturer may have noticed the taint themselves or have received consumer complaints, but not know the cause. Sometimes the problem turns out to be microbiological in origin. An odour of 'nail varnish remover' or 'pear drops', for example, can arise from wild yeast contamination of baked goods.

Problems with taints and off–flavours can cost food and drink companies considerable money and time through wasted product, impact on reputation and lost production. Taint is a sensory issue, but often needs chemical analysis to determine what it is and how it arose. Understanding the cause is crucial in preventing recurrences.

How does taint arise?

Taint can arise from many sources during production, transportation and storage. A few examples of causes of taint include: inadequately cleaned vats, tainted wooden pallets, exposure to cleaning fluids, dirty bottles, or proximity to odorous substances. It can also be due to batch variation, microbial activity and deterioration of foods during storage, the most commonly encountered example of which is rancidity.

We find that taint issues come in two main types:

• the first is when the client knows that there is a problem - for example, they, or a consumer, have detected the taint, and want to know what it is and how it might have arisen
• the second is when they think they may have a problem or where they want to assess the potential for a problem

As a very general rule of thumb, the former will rely on chemical analysis and the latter on sensory analysis.

Comprehensive taint testing, principal component analysis and sensory testing

Having a range of technical services is important for comprehensive taint investigation and we often assess taint from chemical, microbiological and sensory perspectives. In our high-tech lab we use GC-MS (gas chromatography–mass spectrometry) technology which allows us to perform analysis for the vast majority of volatile compounds in a single screening analysis. This allows us to detect and identify tainting compounds without needing to know what they are beforehand.

We can also compare the overall volatile profiles of samples using principal component analysis. This is a statistical technique used on multivariate data sets to display any significant variations between the samples, which due to the huge amount of data involved would not be apparent from visual examination of the raw results. This latter technique can be used for taint investigations but can also be used for flavour analyses of acceptable samples, for example to examine the similarities and differences between different brands of the same product type, or different varieties of the same fruit or vegetable.

As well as analysis using chemistry and microbiological methods, testing by sensory assessment is also critical. At Campden BRI we have the benefit of our sensory panels comprising fully screened, trained or selected sensory assessors. Our sensory panels can help establish whether there is a problem using techniques such as free description profiling and triangle testing. An objective description of the sensory characteristics of a taint can be very important in tracing its source.

Further information

Analytical chemistry
Rob Levermore, Flavour and Taints Group Manager
+44(0)1386 842264
rob.levermore@campdenbri.co.uk

Sensory analysis
Susan Rogers, Sensory Analysis & Testing Section Manager
+44(0)1386 842230
susan.rogers@campdenbri.co.uk