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Department of Food Science, Sensory Science
Wender BredieDepartment of Food Science, KU-LIFE
SAAFoST – ESN lecture evening“Future directions for Sensory and Consumer Science”Pretoria, SA, 15 April 2008
Sensory and instrumental research methods
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 2
Sensory evaluation
The application of analytical and affective sensory evaluation techniques ........ to correlate human reactions to foods with analytical measurements of food and food components
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 3
Classical sensory methodology
"Objective" methods "Subjective" methods Laboratory panel, focus groups Consumer panels
CONSUMER TESTAffective and cognitive testsQualitative and quantitative methods
DESCRIPTIVE TESTQUALITY TEST
DISCRIMINATIVE TEST
Does the difference have any meaning for the consumer?
What characterises the difference and how much?
Is there a difference between products?
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 4
Descriptive analysis
Texture profile
1940
1950
1960
1970
1980
1990
2000
2010
Spectrum QDA
Free-Choice Profiling
Hybrid methods
Progressive profiling
Time-intensity
Flavour profile method (A.D. Little)
High time-resolved Low time-resolved
Flash profile
Various ISO standardsand national standards
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 5
Applications of descriptive analysis
Main fields of applications• Quality control• Product research and development• Calibration of sensors/instruments• Preference mapping
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 6
Sensory – Instrumental relationships
INSTRUMENT SENSORS
HUMAN SENSORS
AND SENSORY/CONSUMERPERCEPTION DATA
CHEMICAL/PHYSICALPHENOMENA AND DATA
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 7
Instrumental product analysis
• Volatile compounds• GC-MS (DHA, SPME-MS, …)• GCO
• Non-volatile compounds• HPLC-DAD; LC-MS/MS; MIMS; Electrodes• Taste dilution analysis (TDA)
• Release of volatile compounds• PTR-MS; APCI-MS; Gas sensors
• Artificial mouth systems
• Correlation to sensory perception• Descriptive analysis; Time-Intensity
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 8
Instrumental in vivo studies
• Brown, W., et al.• Taylor, A., et al.• Prinz, J., et al.• Delahunty, C., et al.• Haahr, A.-M., et al.• …
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 9
Instruments for sensory stimulation
Sense of smell – olfactometerSense of taste – gustometerSense of hearing – audiometerSense of touch – tactilometer
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 10
Instruments for sensory stimulation
Studies odour/taste perception• Intensity, pleasantness, memory, mixtures
Cross-modal interactions• Odour - taste interactions• Texture - odour/taste interactions
Adaptation / cross adaptation• Product optimisation• Structure-activity relationships
Sensory - physiological studies• EEG, EDA, heart rate, EMG, ...
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 11
Applications of descriptive analysis
Methodological aspects• Focus on immediate sensory attributes• Focus on the five senses• Standardisation of test conditions• Removal of contexts
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 12
Immediate sensory responses
Does descriptive analysis describe perceptible product quality well?
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 13
Sensory product quality
• Evaluation of composite attributes (harmony, complexity, …)
• Feelings of hunger, desires, satiety, satisfaction, ...• Evaluate more complex stimuli (meals)• Explore sensory perception in contexts/situations• Observe responses
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 14
Observational methods
Observe sensory induced behavior • Postures, gestures• Facial expressions• Movements• Social interactions
Studying• Acceptance• Choice behaviour• Preference/aversion formation• Eating behaviour
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 15
Helene Hausner, PhD-Student
To investigate early establishment of food preferences. Emphasis is on how early feeding with breast or formula milk affects childhood food preferences and acceptance of novel foods
Early predictors of food preferences
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 16
Study design
The study comprises 2 parts1. Flavour exposure via breast milk 2. Exposure to flavour during complementary feeding
days1 29 50
Preference testing
Mother consume hummus, home
Infant consume potato purée, home
Part 1 Part 2
Habitual diet, home
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 17
Observational laboratory, OBSENSE
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 18
Nutritional meals
VR1 receptorNa+
Neurotransmitters (Substance P)
Pain
DigestionGI tract
Intestinalcell Capsaicin
Absorption
Capsaicin-albumin Portalblood
Adrenalgland
catecholaminesAdrenaline, noradrenaline
Adipocyt
Liver
LipolysisGlycogenolysis
Lipolysis
Substrates
Muscles
Trigeminal stimuli
Heat
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 19
Do spicy meals affect appetite and food intake?
Method40 subjectsFixed meal ±hot spices 9-point category scale: mood, appetite, liking, desiressour, bitter, sweet, salty, fat, hot
Results• Hot spices no effect on food intake• Food intake affected by meal type• Liking positively correlated to food intake• Desire for sweet increased by chilli; mustard decreased desire for
salty
Reinbach, H.C, (2008). PhD thesis, KU-LIFE
Meal 2: ± horseradishMeal 1: ± chilli
pepper
Meal 3: ± ginger
Meal 5: ± wasabi Meal 4: ±
mustard
1041-1042 KJ 989.7- 1040 KJ1956-1996 KJ
1986-2056 KJ1494.7 KJ
Chili Horseradish Ginger Mustard Wasabi0
100
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300
400
500
600
700
To
tal fo
od
in
take
(g
)
Meal
Men Women
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 20
Sensory evaluation in restaurants• Expectation/Surprise• Esthetics• Contexts and situations• Interior designs• Whole meal experience
• Techniques for food preparations• Food physics and chemistry
Molecular gastronomy
Department of Food Science, Sensory Science
Wender Bredie, ESN, Pretoria, SA, 15 April 2008 21
Future …
• Study more complex systems• Instruments for understanding perception• Sensory - physiology relationships• Dynamics in preferences and desires• Exploring situations and information• Gastronomy for health