Sample preparation and serving in practice

Katariina Roininen (VTT, Finland) and María José Sánchez (ainia centro tecnológico, Spain)
 katariina.Roininen@vtt.fi,  mjsanchez@consumolab.es

When a sensory evaluation test is conducted, the product developer and the sensory analyst are looking for some treatment effect. This effect is for example effect of an ingredient change, change in processing variables, in packaging materials or storage time. Therefore one of the primary responsibilities of the sensory analyst is to ensure that no extraneous variable are introduced and real treatment variables are not obscured. This can be done by controlling the handling, the preparation and the presentation of samples.

The controlled preparation of samples requires adequate selection of samples, equipment and methods. The general principle when selecting material for sensory testing is representativeness of the sample or process under study. Special attention much be made to the consequences of selecting sample from single batch. If the samples are taken from only one batch, then there is no information about the variation inherent when making the product. The equipment and container used in sample preparation must be odourless to be sure that we do not introduce biases and new variables for our test. Extreme attention must be given to sample preparation. This requires careful regulation and monitoring of the procedures used. In many instances there is freedom to select any one of a variety of sample preparation methods. For example, when testing potatoes the preparation methods could be frying, boiling, mashing or baking. However, usually this method should represent typical, normal use of the product.

Related to serving procedures, the general philosophy is that the samples presented must be exactly alike with respect to all the factors under experimental control. Among the factors to be considered are visual appearance, sample size, temperature, containers and coding procedures.
Sample serving temperature is determined by the objectives of the test. Uniformity of temperature is generally agreed to be a necessary condition in sensory testing of foods. Samples should be served in containers of the same size and colour.  All samples presented to the judges must be coded in such a way as to avoid giving information to the panel. Assignment of code markings by some method which ensures randomness is essential.

Control of all these aspects has clearly indicated benefits. Furthermore, environmental conditions need to be controlled during the test. These include reducing distraction and providing air conditioning, proper lighting, and comfortable seating.

Accurate sample preparation and presentation ensures valid and reliable results.

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