Principles and Practices by Harry T. Lawless and Hildegarde Heymann
Presenting divergent philosophies in a balanced manner, this comprehensive and up-to-date
text covers all the basic techniques of sensory testing, from simple discrimination tests
to home use placements for consumers.
Offering a balanced view of diverse approaches, the text
presents the chapters in such a way as to provide undergraduate and graduate students taking
courses in sensory evaluation, who want only practical aspects of conducting sensory tests,
with clear instructions on how tests should be conducted. Advanced students will profit from
the more detailed sections on rationale and sensory evaluation issues. Sensory Evaluation of
Food is also an essential reference for industrial practitioners.
- Provides a practical guide to how tests are conducted
- Explores the fundamental psychological and statistical theories
that form the basis and rationale for sensory test design
- Statistics used in sensory
evaluation are demonstrated as integrated applications in the context of appropriate sensory
methods and are also presented as stand-alone material in appendices
- Statistical applications are tailored to common analyses encountered to sensory work,
so that practicality and relevance are obvious, and space is not wasted on designs or
analyses that are not suitable for data collection from human observers
Introduction and overview: Definition and focus. Historical landmarks and the three
classes of test methods. The central dogma - analytical vs. hedonic tests. Applications: why
collect sensory data? Differences from Other Research Methods.
Physiological and psychological foundations of sensory function:
Classical sensory testing and psychological
methods. Anatomy and physiology and functions of taste. Anatomy and physiology and functions
of smell. The trigeminal flavor senses. Sensory interactions.
Principles of good practice: Sensory testing environment. Test protocol considerations.
Tabulation and analysis.
Discrimination Testing: Types of discriminatiom tests.
The ABX discrimination task. Reputed strengths and weaknesses. Data analyses. Binominal
distributions and tables. Issues. Common mistakes made in the intrepertation of discrimination
Discrimination theories and advanced topics: The theory of signal detection.
Thurstonian models for choice tests. Signal detection applied to foods using the R-index.
uessing models and discriminator theory. Estimating sample size in discrimination tests.
The test for significant similarity. Conclusions: Signal detection, Thurstonian, and guessing models
Measurement of sensory thresholds:
Introduction: The appeal of threshold concepts. Empirical thresholds: concepts, issues
and problems. Practical methods: ascending forced choice. Alternative aproaches: rated
difference, adaptive procedures, signal detection. Dilution analysis and odor Units.
Scaling: Practical applications of numbers to sensory phenomena. Common
methods of scaling. Some variations - other scaling techniques. Comparing methods: what
is a good scale? Practical guidelines. Conclusions. Postscript: The 9-point scale revisited-how
they did it.
Time-intensity methods: The approach and its advantages. history of time-intensity
methods. Examples and applications. Data analysis. Problems and remaining questions.
Context effects and biases in sensory judgement: Relative nature of rating scales. Simple contrast
and adaptation level. Range frequency theory. Poulton's classification of biases. Halo effects
and false enhancement from response restriction. Classical psychological errors. Antidotes.
Descriptive analysis: Uses of descriptive analysis. Language and descriptive analysis.
Descriptive analysis techniques.
Texture evaluation: Texture defined. Auditory, visual
and tactile texture. Sensory texture measurements. Texture profile analysis. Instrumental
texture measurements and sensory correlations.
Color and appearance: Color and appearance. What is color? Vision. Measurement of
appearance and color attributes. Instrumental Color Measurement.
Acceptance and preference testing: Consumer sensory evaluation.
Preference tests. Acceptance tests. Variations on acceptance. Qualifying Panelists.
Consumer field tests and questionnaire design: Objectives: Sensory testing versus concept
testing. Testing scenarios: central location, home use. Practical conduct of home use tests.
Interacting with field services. Questionnaire design. Ten rules of thumb for question
Qualitative consumer research methods: Introduction. Characteristics
of focus groups. Using focus groups in sensory evaluation. Conducting focus group studies.
Issues in moderating. Analysis and reporting. Alternative procedures and variations of the
Sensory evaluation in quality control: Objectives and challenges.
Program development and management issues. Methods for sensory QC system. Methods for sensory QC.
Importance of good practice. Summary and conclusions.
Postscript: whither excellence?
Data relationships and multivariate applications: Introduction.
Overview of multivariate statistical techniques. Relating consumer and descriptive data.
Strategic research: Introduction. The
category review. Perceptual mapping and opportunity identification. Consumer contact.
Overview of sensory principles and practices: General considerations in sensory
testing. 50 rules of thumb for sensory testing. Flowcharts for sensory evaluation procedures.
Sensory evaluation in industrial and academic research.
Appendix I: Basic statistical concepts
for sensory evaluation: Introduction. Basic statistical concepts. Hypothesis testing and
statistical inference. Variations of the t-test. Summary: statistical hypothesis testing.
Postscript: What p-values signify and what they don't.
Appendix II: Nonparametric and
binomial-based statistical methods: Introduction to the nonparametic tests. Binomial
ased tests on proportions. Chi-square. Useful rank order tests. Mann Whitney U test. Ranked data
with more than two samples. The Spearman rank order correlation.
Analysis of variance: Introduction. Basic analysis of variance, rationale and worked example.
An interlude for the confused. Multiple factor analysis of variance and the concept of a linear
model. Analysis of variance from
complete block designs and partitioning of panelist variance. Sensory panelists: Fixed or random
effects. Planned comparisons between means following ANOVA. Two-way ANOVA from randomized complete
Split-plot or between-groups (nested) designs. Epilogue: other techniques.
Appendix IV: Correlation, regression, and measures of association: Correlation.
Linear regression. Multiple linear regression. Other measures of association.
Appendix V: Statistical power and testing sensitivity: Introduction. Factors
affecting power of statistical tests. Worked examples. Power in simple difference and preference
Appendix VI: Statistical Tables. Glossary. Index.