Are you a wine expert? No? A food expert, perhaps? No ….really? If, like me, you have a tendency to eat food more than once a day, you really should have been paying attention! But, attending or not, we all have a vast implicit store of knowledge about food, or at least the food that is typical of the culture within which we live. The average consumer can spot a change in one of their regular foods or drinks without very much effort. But what they can’t do is talk very much about that difference, since most of us lack even a basic food vocabulary. And trying to quantify the degree of difference say between two foods is even harder.
For food producers this is a problem. Maintaining the quality of foods can be a challenge when ingredient supplies or storage conditions or packing materials vary. Especially for those foods that are easily influenced by geography or weather or the health of the plant or animal – dairy, wine, olive oil, tea and so on – the expert taster has been a source of information that helps eliminate those samples with faults.
In addition, much of the sensory study of food flavours has been undertaken using experts – specifically trained panellists – whose training is aimed precisely at producing individuals who respond to sensory qualities in an analytical, non-hedonic, and highly sensitive manner [1]. In other words, they are meant to respond entirely unlike the typical consumer. Panellists who are well trained tend to produce data that are reliably reproducible. In contrast, consumers’ data tend to be highly variable, both within (for example, over time) and between individuals. These distinctions are sometimes described as contrasting objective with subjective data, with the implication that the former is intrinsically more desirable for understanding products.
But the trained panel’s apparent advantages come at a cost of reduced ecological validity - that is, application to the real world of consumers. The point of sensory analysis is ultimately to understand the basis of consumers’ decisions about products, which are intimately linked to hedonics. Thus, sensitive trained panellists may describe product differences that are either unperceived by consumers or, even if perceived, then unimportant in terms of their influence on product acceptability. Conversely, minor product differences could potentially exert major effects on food preferences.
Linking measures of product sensory attributes to consumer preferences implies that trained panellists and consumers actually perceive product attributes in the same way. But this is not necessarily true. We know that food flavours reflect the integration – or melding together – of taste, olfactory, and tactile information, and this integration means that these individual sensory attributes are melded together. But the whole approach of experts is to analyse, to break apart this synthesis, and with it the integration that produces the overall food flavour. As one example, this is evident when we asked consumers to be analytical and it reduces their liking for the flavour [2]. So, a major issue with consumers is not just that they are inconsistent and variable in their assessments of sensory properties, but that they also ‘see’ flavour as wholes rather than a collection of parts
As recently as the 1990s, it was accepted that the way to find out about consumer preferences was to ask them about liking – which they are clearly easily able to do – and to find out about the product by using trained experts, most often former consumers who’d had the hedonics knocked out of them. The small panels of tasters were experts because of their ability to focus on the minutiae of a product’s sensory qualities in a highly reproducible way. So, after 20, 40 or 80 hours of training, panelists can understand the difference between cohesiveness and fracturability, or between kerosene notes and acetone notes. When faced with such distinctions, the consumer merely looks bemused.
More recently, however, it has been seen as acceptable to ask consumers to distinguish among different products, either via sorting them into groups – which tends not to require a sensory vocabulary – or in the past few years identifying words that apply to whatever is being tasted methods do not require the development of an extensive vocabulary of relevant terms by the consumers themselves. These check-all-that-apply (CATA) techniques allow an insight into consumer perceptions of the similarities and differences between different samples or products.
The biggest change, though, appears to be emerging in the area of simply telling products apart, that is, discrimination. In an earlier discussion (see The highly discriminating consumer), I pointed out the increasing recognition being given to role of emotions in discrimination and how an emotional state might encourage sensitivity. In turn, this derives from the different ways in which experts and consumers ‘see’ products.
The ability to discriminate between different tastes, flavours or foods is typically seen as a function of perceptual sensitivity derived from detailed analysis of their sensory properties. Hence, trained panels are recommended for such tasks. Conversely, consumers are thought to be relatively insensitive to the presence of, or variations in, sensory qualities, at least when compared to trained panelists, and there has been a reluctance to use consumers to undertake discrimination tests. This practice, however, relies on two assumptions that are increasingly being questioned.
The first of these is that high levels of sensitivity to variations in sensory qualities is always important. In fact, trained panels may over-estimate the effect of variations on consumer preferences. Thus, measuring the concentration of trichloranisol (TCA; also known as cork taint) at which wine consumers would reject wine produced a much higher value that that given by wine tasters trained to be sensitive to TCA. In effect, wines rejected as tainted by the experts would have been perfectly acceptable to the majority of wine drinkers [3].
So, consumers may be entirely appropriate to use in discrimination tasks when making judgments about what other consumers might perceive in products. The question is then how to find differences between products that are actually relevant to consumers? That is, would consumers actually notice the difference and, if they did, would they actually care? In a recently published study, Kim and colleagues [4] used an affective consumer discrimination method. The essence of this test was to perform a standard test of discrimination known as the duo-trio test in which consumers were asked to match one of two unknown stimuli to a reference. In this case, though, the reference was established beforehand as being preferred (affective groups) or no such pre-test was performed (analytical group). They were able to demonstrate that for those consumers who were genuinely “affective discriminators” – that is, they showed a clear preference for the product used as a reference (as compared to non-discriminators) – their ability to match the samples was higher than for an analytical group, who did not undergo this preference pre-test.
Hence, rather than encouraging these consumers to ignore their preferences, actively utilizing these preferences produced superior discrimination. Of course, the presence of sub-groups of ‘affective discriminators’ sounds like unwanted variability of the sort that does not occur with experts. But we should be used to the idea of preference segments. Variability in consumer perceptions and preferences is currently a rapidly increasing area of research (see for example How sweet it is ... or is it?). The key is not to manage-out consumer variability by turning them into experts, but rather measure, identify and interpret the sources of the variability and ask what it tells us about food preference and choices in the population. Eliminating the impact of individual differences means that important variables that have a consistent impact on product perceptions and ultimately acceptability are ignored.
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1. Prescott, J., J. Hayes, and N. Byrnes, Sensory Science, in The Encyclopedia of Agriculture and Food Systems., N.K.V. Alfen, Editor. 2014, Elsevier. pp. 80 - 101.
2. Prescott, J., S.M. Lee, and K.O. Kim, Analytic approaches to evaluation modify hedonic responses. Food Qual. Pref., 2011. 22(4): p. 391-393.
3. Prescott, J., et al., An estimate of the “consumer rejection threshold” for TCA in white wine. Food Qual. Pref., 2005. 16: p. 345-349.
4. Kim, M.-A., H.-M. Sim, and H.-S. Lee, Affective discrimination methodology: Determination and use of a consumer-relevant sensory difference for food quality maintenance. Food Research International, 2015. 70: p. 47-54.
