Lesson 6 - Sensory Analysis

The word description is synonymous with explanation. In descriptive tests we use sensory methods to explain how a beer tastes. As this explanation must work for everyone, the results of the analyses undertaken need to be objective even if undertaken by assessors considering the beer on a subjective basis. The design of the test addresses and corrects this contradiction.

In descriptive analysis we are looking to obtain both qualitative (descriptive) and quantitative (numerical rating) information about our beer. Quantitative descriptive analysis allows us to identify the elements of beer flavour and how the intensity of those elements gives our beer its character.

There are a number of methods for descriptive analysis of beer flavour. Descriptive tests vary from very simple methods with a great deal of freedom to tightly defined, highly focused analyses, and every brewery will have a slightly different approach. Several methods – like Flash Profiling®, the Spectrum Method™, and Quantitative Descriptive Analysis® – are registered trademarks and breweries using them are required to follow the procedure to the letter.

It is beyond the scope of this lesson to describe all tests to a practical level so this section covers the basics and common features of all tests, then focuses on the test protocol given in Analytica EBC.

The simpler methods are referred to as simple or free-choice descriptive tests. In the free-choice tests, we can ask panellists to sample the beer and write a description of what they taste. The most complex and focused are termed quantitative descriptive tests (because what is described is quantified) or sensory/flavour profile analyses. We often use the more complex tests to focus in on a complex component of flavour such as hop character. We need to tightly control all descriptive tests, no matter how simple, to ensure the results are valid and reproducible.

We use descriptive tests in the following areas:

• New product development, establishing the nature of the differences between products

• Quality control

• Storage (or shelf life) trials

• Providing sensory data for correlation with those from ‘conventional’ laboratory tests

• Providing data for production manuals for beers brewed at more than one site

• Providing the ideal model beer for a trueness-to-type test

Descriptive analysis panel training

The panel undertaking descriptive tests needs to be particularly highly trained in the language of beer flavour and also screened for blindness to particular flavours. The EBC suggests the following flavour standards for the test of prospective descriptive panellists.

Table: Flavour standards for descriptive ability from Analytica EBC

The ASBC have a flavour-standards spiking calculator which enables breweries to make their own standards by adding food-grade chemicals to beer. A simpler approach is the use of commercial flavour standard capsules from Aroxa and FlavorActiv. With these, we simply break open the capsules and add to a prescribed volume of subtly flavoured beer. These products come with information cards showing the details of the flavour standards.

The ISO standard for flavour profiling quotes up to a year or even more as an appropriate time for training. It recommends that around ten panellists undertake the tests. This number is chosen to ensure that a full range of sensitivities to flavour compounds is represented on the panel.