Sensory Evaluation of Foods ( Alexandra Oliveira )

Human Senses Human Senses • Many accepted definitions • Many accepted definitions – Senses are the physiological methods of perception – Senses are the physiological methods of perception • Aristotle – There are five senses in humans: • Aristotle – There are five senses in humans: – Sight – Sight – Hearing – Hearing – Touch – Touch – Smell – Smell – Taste – Taste

Human Senses Human Senses • From neurological Sciences – Humans have at least six • From neurological Sciences – Humans have at least six additional senses (at least 11 senses all together): additional senses (at least 11 senses all together): – Nociception – pain – Nociception – pain – Equilibraception – balance – Equilibraception – balance – Proprioception and kinesthesia – joint motion and – Proprioception and kinesthesia – joint motion and acceleration acceleration – Sense of time – Sense of time – Thermoception – temperature differences – Thermoception – temperature differences – Magnetoception – direction (weak in many individuals) – Magnetoception – direction (weak in many individuals) • From all the senses above the only one that may • From all the senses above the only one that may influence sensory evaluation of a food item is influence sensory evaluation of a food item is thermoception thermoception

Human Senses Human Senses • Commonly recognized categorization for human • Commonly recognized categorization for human senses is: senses is: – Chemoreception (taste and smell) – Chemoreception (taste and smell) – Photoreception (sight) – Photoreception (sight) – Mechanoreception (touch) – Mechanoreception (touch) – Thermoception (thermoception) – Thermoception (thermoception) • All human senses fit into one of the categories listed • All human senses fit into one of the categories listed above above

Human Senses Human Senses • Sight or vision: • Sight or vision: – Ability of the brain and eye to detect electromagnetic – Ability of the brain and eye to detect electromagnetic waves within the visible range (light) and interpret the waves within the visible range (light) and interpret the image image • Touch, mechanoreception or somatic sensation: • Touch, mechanoreception or somatic sensation: – Sense of pressure perception, generally in the skin – Sense of pressure perception, generally in the skin • Hearing or audition: • Hearing or audition: – Sense of sound perception – Sense of sound perception – Sound is vibrations propagating through a medium (e.g. air) – Sound is vibrations propagating through a medium (e.g. air) – Detection of these vibrations is a mechanical sense similar – Detection of these vibrations is a mechanical sense similar to ‘touch’ but much more specialized to ‘touch’ but much more specialized

Human Senses Human Senses • Taste or gustation: • Taste or gustation: – This is a “chemical” sense – This is a “chemical” sense – There four main types of tastes that receptors – There four main types of tastes that receptors (buds) in the tongue can distinguish: (buds) in the tongue can distinguish: • Sweet • Sweet • Salt • Salt • Sour • Sour • Bitter • Bitter

Human Senses Human Senses • Taste or gustation: • Taste or gustation: – In 1908 a fifth receptor, for a sensation called – In 1908 a fifth receptor, for a sensation called umami (SAVORIENESS), was first theorized. In 200 umami (SAVORIENESS), was first theorized. In 200 its existence was confirmed. its existence was confirmed. • The umami receptor detects the amino acid glutamate, • The umami receptor detects the amino acid glutamate, a flavor commonly found in meat and in artificial a flavor commonly found in meat and in artificial flavorings such as monosodium glutamate (MSG) flavorings such as monosodium glutamate (MSG) – Most of what we perceive (or describe as taste) is – Most of what we perceive (or describe as taste) is actually smell actually smell • E.g. “This ice-cream tastes like strawberry and banana”; • E.g. “This ice-cream tastes like strawberry and banana”; it actually smells like banana and possibly tastes sweet it actually smells like banana and possibly tastes sweet and sour and sour

Sense of Taste – Our Tongue Sense of Taste – Our Tongue • The majority of taste buds on the tongue sit on raised • The majority of taste buds on the tongue sit on raised protrusions of the tongue surface called papillae. Four types protrusions of the tongue surface called papillae. Four types of papillae present in the human tongue: of papillae present in the human tongue: • Fungiform papillae – Slightly mushroom-shaped if looked at in • Fungiform papillae – Slightly mushroom-shaped if looked at in longitudinal section. These are present mostly at the apex longitudinal section. These are present mostly at the apex (tip) of the tongue, as well as at the sides (tip) of the tongue, as well as at the sides • Filiform papillae – Thin, long papillae “V”-shaped cones that • Filiform papillae – Thin, long papillae “V”-shaped cones that don’t contain taste buds but are the most numerous. These don’t contain taste buds but are the most numerous. These papillae are mechanical and not involved in gustation papillae are mechanical and not involved in gustation • Foliate papillae – Ridges and grooves towards the posterior • Foliate papillae – Ridges and grooves towards the posterior part of the tongue found on lateral margins part of the tongue found on lateral margins • Circumvallate papillae – Only about 3-14 of these papillae on • Circumvallate papillae – Only about 3-14 of these papillae on most people. Present at the back of the oral part of the most people. Present at the back of the oral part of the tongue. Arranged in a circular-shaped tongue. Arranged in a circular-shaped

Sense of Taste – Taste Buds Sense of Taste – Taste Buds Contrary to popular understanding that different tastes map to different areas of the tongue, taste qualities are found in all areas of the tongue although some regions are more sensitive than others View of a portion of the mucous membrane of the tongue. Two fungiform papillæ are shown. On some of the filiform papillæ the epithelial prolongations stand erect, in one they are spread out, and in three they are folded in.

Human Senses Human Senses • Smell or olfaction • Smell or olfaction – This is a “chemical” sense – This is a “chemical” sense – Unlike taste, there are hundreds of olfactory – Unlike taste, there are hundreds of olfactory receptors in our olfactory epithelium (where the receptors in our olfactory epithelium (where the receptor are located) receptor are located) – Odor molecules have a variety of features and can – Odor molecules have a variety of features and can combine with many or few receptors combine with many or few receptors – It is known that there isn’t one receptor for – It is known that there isn’t one receptor for specific kinds of smells, our sense of smell works specific kinds of smells, our sense of smell works with ‘patter recognition’ with ‘patter recognition’

Human Senses Human Senses • Smell or olfaction • Smell or olfaction – This combination of signals from different – This combination of signals from different receptors makes up what we perceive as smell of receptors makes up what we perceive as smell of substances or mixtures of substances (volatiles) substances or mixtures of substances (volatiles) – Volatiles are molecules of low boiling point at – Volatiles are molecules of low boiling point at atmospheric pressure (1 atm or 760 mmg Hg) atmospheric pressure (1 atm or 760 mmg Hg) • Note: Taste is not the same as flavor! • Note: Taste is not the same as flavor! • Flavor includes the smell of a food as well as • Flavor includes the smell of a food as well as its tast its tast – In the strawberry-banana ice-cream example the – In the strawberry-banana ice-cream example the correct description would be ‘This cream has a correct description would be ‘This cream has a strawberry-banana flavor’ strawberry-banana flavor’

Sense of Smell – Our Nose Sense of Smell – Our Nose http://www.senseofsmell.org/feature/smell101/lesson1/01.php

About the Trigeminal Nerve About the Trigeminal Nerve • Sensation of cooling (e.g. menthol, mint) or hot (e.g. • Sensation of cooling (e.g. menthol, mint) or hot (e.g. cinnamon or clove) in back of our throats is not part cinnamon or clove) in back of our throats is not part of ‘taste’ but a response to stimulus in the trigeminal of ‘taste’ but a response to stimulus in the trigeminal nerve nerve – Trigeminal nerve = fifth cranial nerve – Trigeminal nerve = fifth cranial nerve • Responsible for sensation in the face • Responsible for sensation in the face • The fifth nerve is primarily a sensory nerve, but it also has certain • The fifth nerve is primarily a sensory nerve, but it also has certain motor functions (biting, chewing, and swallowing) motor functions (biting, chewing, and swallowing) • There are two basic types of sensation: touch/position and • There are two basic types of sensation: touch/position and pain/temperature pain/temperature

About the Trigeminal Nerve About the Trigeminal Nerve http://www.clinicalexams.co.uk/images/trigeminal_nerve_5.jpg

What is Sensory Analysis? What is Sensory Analysis? • Identification of food product (s) properties • Identification of food product (s) properties • Scientific measurement of food product (s) properties • Scientific measurement of food product (s) properties • Analysis and interpretation of the identified and • Analysis and interpretation of the identified and measured food product properties measured food product properties – AS THERE ARE PERCIVED THROUGH THE FIVE SENSES: – AS THERE ARE PERCIVED THROUGH THE FIVE SENSES: – sight (e.g. color of a food product) – sight (e.g. color of a food product) – smell (e.g. presence of rancidity in a product) – smell (e.g. presence of rancidity in a product) – taste (e.g. intensity of sweetness) – taste (e.g. intensity of sweetness) – touch (e.g. firmness of a muscle food) – touch (e.g. firmness of a muscle food) – hearing (e.g. crunchiness of a potato chip) – hearing (e.g. crunchiness of a potato chip)

What Questions Sensory Analysis Answer? What Questions Sensory Analysis Answer? • Questions that deals with quality of food products • Questions that deals with quality of food products under three main categories: under three main categories: – Discrimination – Discrimination • These questions have the objective of determining if • These questions have the objective of determining if differences exist between two or more products differences exist between two or more products • Type of questions that may be asked in discrimination • Type of questions that may be asked in discrimination sensory tests: sensory tests: – Is product A identical to product B? – Is product A identical to product B? – Find the two similar products among the three – Find the two similar products among the three samples provides samples provides – Find the odd sample among the three samples – Find the odd sample among the three samples provided provided

What Questions Sensory Analysis Answer? What Questions Sensory Analysis Answer? • Questions that deals with quality of food products • Questions that deals with quality of food products under three main categories: under three main categories: – Description – Description • These questions have the objective of describing • These questions have the objective of describing characteristics of a product and/or measuring any characteristics of a product and/or measuring any differences that are found between products differences that are found between products – What does this product taste like? – What does this product taste like? – What are the three most important texture – What are the three most important texture attributes you perceive in this product? attributes you perceive in this product? – For which sensory attributes are the differences – For which sensory attributes are the differences between product A and B most marked? between product A and B most marked?

What Questions Sensory Analysis Answer? What Questions Sensory Analysis Answer? • Questions that deals with quality of food products under three • Questions that deals with quality of food products under three main categories: main categories: – Preference or Hedonics – Preference or Hedonics • These questions have the objective of describing liking • These questions have the objective of describing liking or acceptability of a product or acceptability of a product – Do you like this product? How much do you like this – Do you like this product? How much do you like this product on a scale of 1 to 10, where 1 = dislike product on a scale of 1 to 10, where 1 = dislike extremely, and 10 = like extremely? extremely, and 10 = like extremely? – Is this product acceptable? – Is this product acceptable? – What do you like most about this product? – What do you like most about this product? – Is product A better then product B? – Is product A better then product B? – Which of the three products A, B and C do you – Which of the three products A, B and C do you prefer? prefer?

Why Use Sensory Analysis to Evaluate Why Use Sensory Analysis to Evaluate Food Products? Food Products? • To evaluate quality (quality control) or improve • To evaluate quality (quality control) or improve quality quality – E.g. Maintain a product with same sensorial characteristics – E.g. Maintain a product with same sensorial characteristics so consumers of that product continue to buy it so consumers of that product continue to buy it – E.g. Release production batch for sale because the – E.g. Release production batch for sale because the products inspected meet the standards set by the products inspected meet the standards set by the manufacturer manufacturer – E.g. Reject production batch because the products – E.g. Reject production batch because the products inspected are below the acceptable level of quality set by inspected are below the acceptable level of quality set by the manufacturer the manufacturer • To provide input for decision making (product • To provide input for decision making (product development) development) – E.g. Launching a new fruit snack, or a new flavor fish stick – E.g. Launching a new fruit snack, or a new flavor fish stick

Why Use Sensory Analysis to Evaluate Why Use Sensory Analysis to Evaluate Food Products? Food Products? • To determine the market value of a product • To determine the market value of a product – E.g. Determine value of perishable products such as fish. If – E.g. Determine value of perishable products such as fish. If fish is very fresh and was handled with great care, then it fish is very fresh and was handled with great care, then it is likely to be sold for a higher price then frozen fish that is likely to be sold for a higher price then frozen fish that has kept in frozen storage for 6 months has kept in frozen storage for 6 months • To determine shelf-life of a product • To determine shelf-life of a product – E.g. How long can a cracker remain in the groceries shelves – E.g. How long can a cracker remain in the groceries shelves before it becomes stale? before it becomes stale? • Ingredient substitution in product formulation • Ingredient substitution in product formulation – E.g. Cost reduction of a product formulation by – E.g. Cost reduction of a product formulation by substitution of ingredient A for ingredient B. Does it change substitution of ingredient A for ingredient B. Does it change the product? Can the consumer perceive it? How does it the product? Can the consumer perceive it? How does it changes the product? changes the product?

Why Use Sensory Analysis to Evaluate Why Use Sensory Analysis to Evaluate Food Products? Food Products? • To compare a product (s) with the competitor‘s • To compare a product (s) with the competitor‘s product (s) product (s) – E.g. How close in taste is beverage A produced by company – E.g. How close in taste is beverage A produced by company A as it compares to beverage B produced by company B? A as it compares to beverage B produced by company B? • To determine storage conditions • To determine storage conditions – Should the product be stored refrigerated, frozen or at – Should the product be stored refrigerated, frozen or at room temperature? room temperature? – Will the product become rancid very quickly if it sits at – Will the product become rancid very quickly if it sits at room temperature? (butter; cheese…) room temperature? (butter; cheese…) – Will the product change texture, appearance or taste if it – Will the product change texture, appearance or taste if it is stored frozen? (eggs; milk…) is stored frozen? (eggs; milk…)

Sensory Evaluation Pitfalls Sensory Evaluation Pitfalls • Determining the wrong objective for conducting • Determining the wrong objective for conducting sensory analysis sensory analysis • Choosing the wrong set of participants in the sensory • Choosing the wrong set of participants in the sensory test(s) test(s) • Asking the wrong questions to the participants • Asking the wrong questions to the participants • Having biased judgments of the products tested • Having biased judgments of the products tested • Lacking scientific control (scientific rigor) • Lacking scientific control (scientific rigor) • Conducting the sensory test in the wrong • Conducting the sensory test in the wrong (inadequate) environment (inadequate) environment

http://images.google.com/images?hl=en&rlz=1G1GGLQ_ENUS309&q=pictures+of+sensory+panel+room&um= 1&ie=UTF-8&ei=heneSbztAYSotAPN8PSxCQ&sa=X&oi=image_result_group&resnum=1&ct=title S S e e n n s s o o r r y y P P a a n n e e l l R R o o o o m m s s

Sensory Panel Room Sensory Panel Room • Round table – mostly for product development (e.g. • Round table – mostly for product development (e.g. launching new product; change in product launching new product; change in product formulation) and internal sensory assessment (e.g. formulation) and internal sensory assessment (e.g. consumer complain) consumer complain) • Booths are widely used to provide an environment • Booths are widely used to provide an environment that prevents panelists from being distracted and that prevents panelists from being distracted and interacting with other panelists – unbiased evaluation interacting with other panelists – unbiased evaluation – Booths can be computerized so panelists enter the answers – Booths can be computerized so panelists enter the answers to the sensory assessment questions electronically to the sensory assessment questions electronically – Booths may have features that change environmental – Booths may have features that change environmental conditions such as different colors of light to mask product conditions such as different colors of light to mask product color color

Sensory Panel Room Sensory Panel Room • Noise level should be kept low • Noise level should be kept low • Room should be free of foreign odors • Room should be free of foreign odors • Testing are should be well lit and ventilated • Testing are should be well lit and ventilated • Testing area should be easy to clean and disinfect • Testing area should be easy to clean and disinfect (sanitation) (sanitation) • Temperature and relative humidity should be • Temperature and relative humidity should be constant and controllable constant and controllable • The room where food products are prepared for • The room where food products are prepared for sensory testing is generally separated from the sensory testing is generally separated from the testing area testing area

Sensory Panel Room Sensory Panel Room • Large room normally are used for testing products • Large room normally are used for testing products using consumers – Untrained panelists using consumers – Untrained panelists • Panelists (participants) can be trained to evaluate • Panelists (participants) can be trained to evaluate specific products (odor, taste, texture, and or visual specific products (odor, taste, texture, and or visual evaluation) evaluation) • At time before training panelists are screened for • At time before training panelists are screened for sensitivity in order to remove from the group of sensitivity in order to remove from the group of panelists people that may not have the ability to panelists people that may not have the ability to perform the sensory evaluation (e.g. people with perform the sensory evaluation (e.g. people with specific type of anosmia – inability to smell certain specific type of anosmia – inability to smell certain odors) odors)

Sensory Analysis Questionnaires Sensory Analysis Questionnaires • It needs to address the main question being tested • It needs to address the main question being tested • Questionnaires are variable and need to be design in • Questionnaires are variable and need to be design in a simple, practical way to yield clear and concise a simple, practical way to yield clear and concise answers answers • When designing a sensory questionnaire (also called a • When designing a sensory questionnaire (also called a sensory ballot), one needs to take into consideration sensory ballot), one needs to take into consideration the audience (panelists) the audience (panelists) – E.g. children vs. adults, trained panelists vs. untrained – E.g. children vs. adults, trained panelists vs. untrained panelists, etc… panelists, etc…

Sensory Analysis Questionnaires Sensory Analysis Questionnaires Triangle Sensory Test on Cookies Please take a drink of water before tasting cookie samples. Eat cookie samples from left to right, and please take a sip of water between samples. Place an “X” under the cookie which is different than the others. 767 312 189 ___ ___ ___ Comments:

Sensory Analysis Questionnaires Sensory Analysis Questionnaires

Types of Sensory Tests Types of Sensory Tests • DISCRIMINATION TESTS • DISCRIMINATION TESTS • Paired Comparison Tests – Testing for differences between • Paired Comparison Tests – Testing for differences between two samples two samples – Simple test: request panelist to taste two samples and respond if the – Simple test: request panelist to taste two samples and respond if the samples are identical or different samples are identical or different – More complex tests can involve differences is specific attributes) such – More complex tests can involve differences is specific attributes) such as sweetness, bitterness, type of odor.. as sweetness, bitterness, type of odor.. • Duo-Trio – Panelists evaluates three samples, and one of them • Duo-Trio – Panelists evaluates three samples, and one of them is marked as reference. Panelist is asked to pick the sample is marked as reference. Panelist is asked to pick the sample that is closer in taste, odor, etc.. To the reference sample that is closer in taste, odor, etc.. To the reference sample • Triangle Test – Panelists evaluates three samples, two are • Triangle Test – Panelists evaluates three samples, two are identical and one if different. Panelist is requested to pick the identical and one if different. Panelist is requested to pick the sample that is different sample that is different

Types of Sensory Tests Types of Sensory Tests • DESCRIPTIVE SENSORY ANALYSIS • DESCRIPTIVE SENSORY ANALYSIS – Useful when a detailed specification of the sensory – Useful when a detailed specification of the sensory attributes of a product is desirable attributes of a product is desirable – Also, it can be useful for comparisons between products – Also, it can be useful for comparisons between products when descriptions of differences are needed when descriptions of differences are needed – Normally uses trained panelists – Normally uses trained panelists – Some of descriptive sensory analysis methods: – Some of descriptive sensory analysis methods: • Flavor ProfileÒ; Quantitative Descriptive Analysis (QDA) Ò, Texture • Flavor ProfileÒ; Quantitative Descriptive Analysis (QDA) Ò, Texture Profile Ò; Sensory Spectrum Ò; Generic Descriptive Analysis; Free- Profile Ò; Sensory Spectrum Ò; Generic Descriptive Analysis; Free- choice Profiling, etc… choice Profiling, etc…

Types of Scales Types of Scales • Many types of scales available… • Many types of scales available… • Numerical scale • Numerical scale – E.g. Intensity: (weak) 1 2 3 4 5 6 7 8 9 (strong) – E.g. Intensity: (weak) 1 2 3 4 5 6 7 8 9 (strong) • Verbal categorical scales • Verbal categorical scales – E.g. Oxidized flavor: not noticeable; trace; faint; mild; moderate, – E.g. Oxidized flavor: not noticeable; trace; faint; mild; moderate, strong, very strong strong, very strong • Ranking or ordering scales • Ranking or ordering scales – E.g. Preference between products A, B, C: 1 most preferred, 2 – E.g. Preference between products A, B, C: 1 most preferred, 2 intermediate preference; 3 least preferred intermediate preference; 3 least preferred • Magnitude of differences (interval scale, see sturgeon • Magnitude of differences (interval scale, see sturgeon example slide 8) example slide 8) • Hedonic scaling for children (‘smiley face model’) • Hedonic scaling for children (‘smiley face model’)

Quality Index Method and Fish freshness Quality Index Method and Fish freshness • QIM was designed to standardize the method to • QIM was designed to standardize the method to evaluate fish freshness for different fish species evaluate fish freshness for different fish species • It is a method that takes in consideration the sensory • It is a method that takes in consideration the sensory attributes that different fish species have attributes that different fish species have • Uses well defined experimental conditions • Uses well defined experimental conditions • Uses trained panelists • Uses trained panelists • It is based on the calculation of a “Quality Index” • It is based on the calculation of a “Quality Index” that is determined from the scores given for a that is determined from the scores given for a product for each attribute evaluated. E.g. product for each attribute evaluated. E.g. appearance of the gills, firmness of the fish muscle, appearance of the gills, firmness of the fish muscle, dullness of the eyes, fillet color, etc… dullness of the eyes, fillet color, etc…

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