Definitions and application of sensory evaluation

INTRODUCTION AND BACKGROUND

How we use our senses
• By using our senses we
decide
– Whether we like a product or
not
– Warnings, sense danger
– Differing levels of important
attributes dependent on the
product
 Brief history

• Sensory testing has been ongoing for centuries

– Individual judgements
– Use of experts as judges of quality
• More systematic approach started in the 1940s
– Use of panels
– Methodological and experimental approach

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 Current state of sensory evaluation

• Collection of techniques and methods for systematic analytical

evaluation of foods and drinks
• More methods continue to be developed
• Methods must ultimately be appropriate for the purpose
• Good sources of reference:
– Journal of sensory studies
– Chemical Senses
– FQP
– Conferences
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Definition for sensory evaluation?

A scientific method to evoke,

measure, analyze and interpret
those responses to products as
perceived through the senses
- IFT
 Defining sensory evaluation – the 4 processes

• Four main processes involved in sensory evaluation:

• To evoke
– Sensory evaluation provides guidelines concerning sample
preparation and serving to minimize bias
• To measure
– Sensory evaluation is a quantitative science producing numeric data
– Allows associations between product characteristics and human
perceptions to be established

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 Defining sensory evaluation – the 4 processes

• To analyse
– Highly variable human data requires proper analyses of data
– Statistical analyses is a most useful tool to establish real as opposed
to random variability
• To interpret
– Sensory evaluation is an experimental process
– Interpretation should be done in the context of a hypothesis
– Consider also background information and implications for decisions

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 The science in sensory evaluation
• Sensory evaluation is a measurement science
• Important aspects of this science are:
• Validity and Repeatability
• To achieve these and maintain it as an objective method, tests
must be conducted under controlled conditions using:
– Appropriate Experimental design
– Appropriate Test methods
– Appropriate Statistical analysis

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 The science in sensory evaluation

• An objective science, but also subjective

– Use of humans as instruments
• Subjective methods are influenced by
psychological factors
• Statistical methods are used to avoid
misleading conclusions
– CAUTION: Use scientific knowledge about product
properties and background information to
interpret statistical findings logically
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 Importance of sensory evaluation
• Instruments cannot duplicate
….human sensory evaluation will always be a most
critical component for advancing the industry’s human senses
assurance of higher quality dairy products for consumers
• Sensory evaluation is
…..sensory evaluation could contribute pertinent,
valuable information related to marketing consequences
foundational for
and simultaneously provide direct actionable
information….
– Advancing quality assurance
– Providing valuable marketing
……there remains no machine or instrument that can
duplicate or fully replicate the human perception of
insights
flavour. Sensory analysis remains the foundation…… – Providing actionable information
M. Drake et al. 2009 for product development
 Importance of consumer research

• Consumer research is useful in many ways:

– Product concept and prototype testing
– Domestic and export market consumer profiles
– Customer motivation and how this can shape marketing strategies
– Demand, purchase intent and consumer willingness to pay
– Consumer threshold for defects
• These trends are shaping the scope of research in sensory and
consumer research
Reading – Meiselman, H. 2012. The future of sensory/consumer research….evolving to a better
science. Food Quality and Preference. Article in Press
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 Applications of sensory evaluation
• Sensory evaluation can be used in various industries for
product characterisation and evaluation:
– Extensively in the food and drinks industry
– Monitor environmental odours
– Personal hygiene products
– Testing of pure chemicals
– Other FMCG
– In the pharmaceutical and medical industry

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 Uses and application of sensory data
• Principal uses of sensory evaluation are in
– Quality control
– Product development and improvement
• Ingredient formulation/interaction and changes
• Process changes
• Packaging changes and interactions
• Shelf life testing
– Research

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 Some specific aims for sensory analysis in food
industry

• Characterize sensory changes in foods

• Distinguish between batches or sources of a
particular product
• Ascertain whether quality can be represented
by a simple numerical index or whether it is
multi dimensional

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 Specific aims cont.
• Help establish standards for raw and processed
food products
• Grading products according to agreed quality
classification system
– Eggs, wine etc
• For consumer preference/acceptability studies
• Correlate objective and sensory data
– Consumer acceptability
– Product attributes
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 Other terms used
• Organoleptic testing or analysis
• Taste test
• Sensory analysis
• Consumer testing
• Sensory panels
 Future trends of sensory analysis
• Competition in the market place has widened the
field of Sensory Analysis to include Consumer
Science and Research
• Consumer Research provides information about
potential customers and is crucial to product
success
• Various methods are used in consumer research
and are often qualitative
– E.g. focus groups, surveys, experimental auctions, at-
home trials and novel interview methods to
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understand how consumers think and feel about food
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• The human senses
• Factors that affect sensory judgement

PRINCIPLES OF SENSORY EVALUATION

 Objectives
• To explain how the human sense perceive sensory stimuli
• To explain how to reduce bias in obtaining sensory data
• To describe some sensory properties of foods
 Learning outcomes
• At the end of the session you will be able to
– Explain how we use our senses to perceive sensory stimuli
– Know about the sensory properties of foods
– Know your individual taste sensitivity to basic taste stimuli
The human senses
• Eyes
– Sight
• Nose
– Smell/odour
• Mouth
– Taste and touch
• Ears
– Hearing/auditory sound
• Skin
– Touch
 Sensory perception

• The process is not one step

• Environmental stimuli
impinge on our senses
• Information is sent to the
brain
• The brain translates the
stimuli into a response
 Types of sensory responses
• Objective response • Subjective response
– Intensity of the stimulus and – Statements of feelings about the
sensation sensation
– Memory and learning – Emotions
 Order of sensory perception
• General order for sensory perception
– Appearance
– Aroma
– Flavour
– Mouthfeel
– After taste/feel
• In reality there is overlap
• All the attributes perceived influence
how we enjoy food
Which of these products is fresher?
Sensory properties and how we perceive them
 Appearance and Vision
• Vision is the psychological response to objective stimulus
generated by the physical nature of an object
• Appearance is the recognition and assessment of the
properties of the object seen
– It involves more than just colour
 Vision
• The eyes are used for seeing
objects
• Vision is the first sense often
engaged when evaluating
food
• Can influence perception of
other sensory properties of
food
 Appearance
• It entails more than colour
• Includes properties such as:
– Size and shape
– Surface texture
– Clarity
– Composition
– Packaging
Colour

• Three components of colour

from physical viewpoint
– Hue – the actual colour
• E.g. Yellow colour
– Intensity – strength of the colour
• From light to dark
– Purity – brightness of the colour
• Dull to pure
 Factors affecting the appearance of colour
• Factors that affect colour • Colour blindness
vision – 8% males and 0.44%
– Composition of the object females are colour blind
– Composition of light – Commonest is red/green
source colour blindness
– Sensitivity of the viewer – Important to screen for
colour blindness
Colour blindness
• Commonest type is
red/green blindness
• Typical in males than in
females
• Other forms of colour
blindness
• Important to know your
status especially as colour is
important for measuring
product quality
 Factors affecting appearance
• Other appearance properties (as well as colour) may be
affected by:
– Lighting
– Background
– Contrast

Source: http://ecolightsolutions.com.au/products-services/
Contrast effect
Background effect
 Write the numbers you see in the discs below

Source: http://ishiharatest.blogspot.com/2011/03/ishihara-color-blindness-test.html
Write the numbers you see in the discs below
Write the numbers you see in the discs below
 Aroma
• Response from volatile stimuli perceived in nasal cavity
• Perceived through nose and mouth
• Smell – odour – bouquet – fragrance
– Aroma of food
– Fragrance of perfume
• Aromatics
– Volatiles perceived by olfactory system from substances in mouth
• Mammals have a strong sense of smell
• The olfactory system can differentiate between odorants with very similar
structures
 Aroma
• Receptors easily saturated
• Specific anosmia common in
people
– Insensitivity to specific odourants
• Can give very strong response at
low levels depending on
thresholds
• Level of aroma/odour is affected
by temperature & nature of
compound (surface conditions)
 Which of these will have a stronger aroma? What
factors influence aroma?

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 Factors that influence aroma

• Odour molecules are transmitted by gas

• Intensity of odour depends on amount of gas which
comes into contact with olfactory receptors
• Tasting may give higher perception of odour than
smelling
• At a given temperature, more volatiles escape from soft,
porous, humid surface than hard, smooth, dry ones
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 Taste
• Response from dissolved
in volatile stimuli
(chemicals)
 Basic tastes

• Other basic tastes

– Metallic (France)
• Metal ions, fat
breakdown etc
– Astringent/drying
• Reaction between
salivary proteins and
phenolic compounds
 Factors that affect taste
• concentration
• temperature
• viscosity
• rate
• duration
• area of application
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 Taste interactions

• Mixtures of tastes show partial inhibitory or

masking interactions

• Interactions are seen in all taste categories

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 What is flavour
• A combination of
– Smell
– Taste
• Associated with retronasal olfaction
– Smells perceived through the mouth
• Also some flavours are chemical irritation or trigeminal
sensation
– Cooling (menthol)
– Heat (chilli peppers)
 Flavour
• Flavor depends on odor, texture, and temperature as well as on
taste.
 Touch or feeling

• Has a high degree of variability due to presence of many neurons on

different parts of the body
 Texture
• Direct and indirect
• Texture of food products mainly
influenced by touch
• Texture also influenced by
hearing and vision
• Difficult to agree on descriptors
• More important to consumers
than they realise
 Hearing
• Often is together with
other properties
• The sound of texture
• Fizz of carbonation
• Snap of chocolates/snack
foods
• Crunch of apples
http://www.pond5.com/sound-effect/48584073/human-
eating-crunch-bite-apple-carrot-crisps.html