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University of Horticultural Sciences, Bagalkot

Principles of sensory evaluation of Essential oils

Presentation on,

Shivanand, M.R.UHS11PGM143Dept. of PMA

KITTUR RANI CHANNAMMA COLLEGE OF HORTICULTURE, ARABHAVI 591 218

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• Quality of any product - acceptance by the consumer

- marketability

• However, it was realized that without sensory evaluation, the

acceptability of a product cannot be determined

• In the past, human sensory perception has been the only means

of evaluation of quality as illustrated by the classical examples

of cooks, who knew, how to mask the off nodes long before

microbial assessment of quality came into existence

The product quality was being traditionally determined by physical,

chemical and microbiological criteria with the assumption that the

products meeting the prescribed specifications in the above parameters

would automatically meet the desired sensory quality

However, soon it was realized that without sensory evaluation, the

acceptability of a product cannot be determined

The sensory evaluation is of great significance as a quality control tool in

the oil processing plant

Sensory analysis maintains the product quality and pattern matching with

the consumer concepts and provides a mean to optimize the product

successfully

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“Sensory analysis is a scientific discipline used to

measure, interpret and analyse reactions to those

characteristics of foods and materials as they are perceived

by the senses of sight, smell, taste, touch and hearing”.

Definition

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To understand the difference between trained and untrained testers

To know which senses are used in sensory evaluation

To understand how sensory tests are used

To know the different tests commonly used in the oil industry

To influence product listings with retailers by presenting

independent research demonstrating that the company has a

greater understanding of their products profile and consumers

To understand how the product performs against competitors

Objectives

The role of sensory evaluation is to….

provide valid and reliable information to R&D,

production, and marketing for management to

make sound business decisions about the

perceived sensory properties of products.

Sensory Evaluation

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Major components of sensory evaluation are:-

The human sense organs (the judges)

Methods of sensory evaluation

The laboratory

Data analysis and interpretation

Components

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Human Senses

Touch

Sight Smell Taste

Hearing

We tend to perceive the attributes of a any item in the following order…..

AppearanceOdor / aroma / fragranceConsistency and textureFlavor (aromatics, chemical feeling, taste)

Sensory Attributes

Sensory Evaluation

There are at least three steps in the process of sensory perception:

Essential oils are perceived by senses individually and processed by brain into total impression of quality

Impression of Flavor

Taste Odor Mouth feel

Trigeminal perception

Flavor

The overall impression of flavor is a combination of taste, odor, mouthfeel, and trigeminal perception

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Types of Panelists

Consumer (untrained)Semi-trained (experienced)Trained (highly experienced)Responses recorded on ballots (scorecards)

Expectations form Panelists

To produce reliable and valid data, the sensory panel

must be treated as a scientific instrument

It is therefore, necessary that panelists are free from

any psychological features and physical conditions

which might affect human judgments

Panelists must have an ability to perform the task and

to repeat their judgments

It is necessary that each panelist must be free from

the following defects:

Taste perception disorders

Odour perception disorders

Color blindness

Denture defects

Allergies

Use of those medications that effect the ability to taste

Sensory ability

Psychological Factors Affecting Sensory Panel

Expectation Error- This occurs when panelists are given too

much information about the samples. Therefore the

panelists should not be informed about the types of

ingredients used in the sensory testing.

Suggestion Error- This occurs when panelists are aware of

reactions of others during the sensory evaluation. This

should be addressed by providing panelists with individual

sensory booths (designed as per the details shown earlier).

Halo Effect- Sometimes panelists evaluate more than one quality

characteristic at a time. They should therefore be trained and

instructed to evaluate each quality parameter separately.

Central Tendency Error- Panellists may choose the mid range to

avoid extremes. All panelists should therefore be advised to

choose the correct scale for each quality characteristic rather than

just selecting the mid range of the scale to avoid extremes.

Order Effect- This may affect the panelists if the sensory samples

are provided in a defined order. All samples to be presented in a

random order with a three digit number assigned to each sample to

avoid the order effect.

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Ballots / Scorecards

• Developed for specific experiment, date, name of

judge

• Listed in order of evaluation

• Descriptive characteristics need careful descriptions

& way to score numerically

• Acceptability

STEPS IN SENSORY EVALUATION

Define overall project objective

Define test objective

Screening the samples

Designing the test (method and judges)

Conducting the test

Analyzing the data

Reporting the results

CONTROLS IN SENSORY EVALUATION

Temperature

Lighting

Atmosphere -smell

Individual booths

Sample selection (identical code dates)

Coding samples (3 digits codes)

Sample preparation

Sample presentation

Subject selection

Guidelines help to improve sensory evaluations:

Please read instructions carefully

Take as much time you need to arrive at your decision

Note a flavor sensations when judging - initial, overall, and

aftertaste

Evaluate samples from left to right, as they face you on the tray

Rinsing your mouth with water between each tasting helps remove

the flavors and “standardizes” your mouth for the next test

When testing between products with strong aftertaste, give

yourself 1-2 minutes between tasting to avoid flavor carryover

Making sounds like groaning, laughing, or talking during the

evaluation may influence others. Please use the form for

recording all your sensations

If you avoid eating, drinking, chewing gum and smoking 1/2

hour before tasting, it will sharpen your ability to taste and

smell

Check your results as they leave to see how you did

It’s a great temptation to share your “taste experience” with

others. Please wait until everyone has tasted, so you can’t bias

their judgement

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Different tests in sensory evaluation

1) Discrimination test

2) Affective test

3) Preference test

a) Paired comparison test

b) Ranking test

c) Hedonic scale test

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Difference between two or more products

The product A is identical to product B

Find two similar products among three samples

The type of panel required for this type of testing

would normally be a trained panel

1) Discrimination test

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Also known as consumer testing, this type of testing is concerned

with obtaining subjective data, or how well products are likely to be

accepted

Usually large (50 or more) panels of untrained personnel are recruited

for this type of testing, although smaller focus groups can be utilised

to gain insights into products

The range of testing can vary from simple comparative testing (e.g.

Which do you prefer, A or B?) to structured questioning regarding the

magnitude of acceptance of individual characteristics (e.g. Please rate

the "fruity aroma": dislike/neither/like)

2) Affective test

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It involves the biochemical and psychological theories relating to human sensations.

a) Paired comparison test –

Two samples – 1) Standard (control)

2) Experimental

b)Ranking test –• Several samples differ on the basis of single characteristics • Rank will be given for similar products

c) Hedonic scale test – • Measure consumer acceptability of the products • Products are scored on a 5 or 9 point scale

3) Preference test

Descriptive analysis - As a major branch of the sensory science,

descriptive analysis is widely used for collecting people's sensory

opinions on an object being food, cosmetics, apparel items, etc

Normally, for descriptive analysis, a minimum of 5 experts is

required, while with respect to naive panelists, this number should

be much bigger

The sensory experiment should be carried out according to

standardized techniques and procedures designed before the

evaluation

After experiments, statistical analysis is often applied to the

interpretation of the sensory results obtained

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Sensory Evaluation Grading System

Category Excellent Very Good

Good Satisfactory Unsatisfactory

Quality Level

Outstanding /Exceptional

Superior/ Very

Correct

Typical Weak/Not at full potential

Faulty / Defective

Grading System

Five grading categories

www.ngfl-cymru.org.uk

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Grading Form

Characteristics & Attributes

Grading CategoriesComment

ExcellentVery Good

Good Satisfactory Unsatisfactory

Appearance & Colour

Aroma

Correctness

Intensity

Quality

Taste

Correctness

Intensity

Finish

Quality

Harmonywww.ngfl-cymru.org.uk

Sensory evaluation of nutmeg seeds essential oil

Characteristics ObservationOdor Turpentine-like or spicy

Odor intensity Strong

Taste pungent and spicy

Color Colorless to pale yellowClarity

clear

Solubility Insoluble in water, soluble in ethanol,

petroleum ether, diethyl ether,

chloroform

Qualitative and Quantitative Analysis

Qualitative testing helps to determine exactly what

individual constituents are present in an essential oil,

and quantitative testing provides information on how

much of each component is present

This is very important because it is well known by

experts that for any given essential oil, here are

several origins and the quality between them varies

tremendously

Physical parameters

If an essential oil sample passes all of the sensory tests, the next

stage is to test the physical parameters of the essential oil by

means of measuring the Specific Gravity, Optical Rotation and

Refractive Index

The combination of these physical tests is usually sufficient to

determine if it is worth proceeding to the final stage of testing an

essential oil

If an oil successfully passes the first two stages it is then tested

using Gas Chromatography/Mass Spectrometry (GC/MS)

Gas chromatography When using Gas Chromatography to test an essential oil, a tiny

sample of the oil is injected (pictured right) into the apparatus

which contains a very thin coiled silica tube called a 'capillary

column'

This capillary column may measure up to 100 meters in length

and is coated on the inside with a material that has an affinity to

different chemicals at different temperatures

The column is housed within a temperature regulated oven and is

programmed to steadily increase in temperature over a period of

time in a very precise manner

When the sample of oil is injected into the column it immediately

vaporises, and an inert carrier gas (usually hydrogen or helium)

moves the vapour along the column to a detector called a Flame

Ionisation Detector which is situated at the end of the column

The flame ioniser detector responds quantitatively to the

vaporised constituents of the oil and converts this information,

via an integrator/computer, into proportional peaks printed onto

computer listing paper. The height of every 'peak‘ on the graph

corresponds proportionally to the level of that component within

the oil

Every individual component of the essential oil can be

identified by the time at which the peak elutes on the

trace. The data produced can then be compared to an

established 'profile' or 'fingerprint' for that particular

essential oil to finally determine the purity of the oil

Adulterants can usually be identified by this means of

testing, although it does require the expertise of an

organic analytical chemist

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Distinguish between the products

Test the popularity of products

Describe specific product attributes

Maintain consistent uniform product quality

Profile the characteristics of a modified product against those of

an original product

Developing new products

Measure shelf life of the product

Industrial applications of sensory evaluation

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Selecting wrong objective for sensory analysis

Choosing wrong participants for the sensory test

Asking wrong questions of the participants

Judgments biased against the products tested

Lacking scientific control

Conducting test in an inadequate situations

Sensory evaluation pitfalls

Thank You