Barley for Food and Health: Science, Technology, and Products

SENSORY EVALUATION 141
as Stone and Sidel (1993) should be consulted for the theory and organization
of a program. Guidelines for specific tests can be obtained from the American
Society for Testing and Materials (Conshohocken, Pennsylvania). Sensory testing
can be done in two general ways: groups of untrained consumers ascertain general
acceptance of a product, or a trained laboratory taste panel can be used. The
latter is much more involved but provides much more specific information. The
consumer panel should have a large number of members, representing a cross
section of a population, who are given a sample and asked to complete a very
simple evaluation such as “like” or “don’t like.” This type of testing provides
only a general idea of product acceptability; however, the results can indicate the
advisability of further, more precise evaluation.
The physical area for trained taste panels should be a quiet, neutral environment
with privacy booths or spaces for panelists and an arrangement for
presentation of samples for testing. Training of panelists involves various aspects
of taste recognition and knowledge of quality factors of the specific type of
food to be tested. Standardized testing procedures should be used and results
should be analyzed statistically, which requires an adequate number of panelists
to assure reliable results. Three categories of tests are used in sensory evaluation:
discriminative, descriptive analysis, and affective (Stone and Sidel 1993). Discriminative
testing may use such simple tests as the paired comparison test, in
which two samples are presented and the panelists are asked if they can discern
a difference. Another is the triangle test, where three samples are presented, two
of which are identical and the panelists are asked to identify the off sample.
In descriptive analysis tests, a quantitative total sensory description of a product
is provided, necessitating thorough screening and training of panelists. They
may be asked to identify various aspects of flavor, aroma, presence of aftertaste,
chewiness, crunchiness or stickiness, or any other impressions of a product. The
third category, affective testing, indicates acceptance or preference of a product
by making a choice between two samples presented. Another form of affective
testing is the hedonic scale, in which panelists rate a product on nine points,
ranging from “like extremely” to “dislike extremely.” Facial image scales are
also used, where panelists (sometimes children) choose a facial expression close
to their reaction to a product. Additionally, the visual analogue scale (VAS) is
used to measure the satiety of a food by assessing degree of hunger, fullness,
nausea, desire to eat, and amount of food that can be eaten at a meal (Flint
et al. 2000).
Preparation of food samples to be tested must be carried out carefully so that
the appearances are identical. All samples must be equally fresh, of equal temperature,
in sizes only large enough for two bites. The order of presentation is
randomized and panelists should not be overwhelmed by the number of samples
at a sitting. Room-temperature water should be provided for mouth rinsing
between samples. Panelists are required to complete score forms to be used for
analysis of results. Documentation and record keeping are essential for credibility
of a sensory evaluation program. Decisions about research directions, product
development, and marketing may be dependent on the results.