Flavour Chemistry

Dr Kieran KilcawleyDr Kieran KilcawleyTel: 00 353 (0)25 42245/42445Tel: 00 353 (0)25 42245/42445Kieran.kilcawley@teagasc.ieKieran.kilcawley@teagasc.ieflavour.chemistry@teagasc.ieflavour.chemistry@teagasc.ie

Flavour Chemistry

• Flavour comprises of

• ~ 75% Aroma• ~ 25% Taste

Flavour Chemistry

• Peptides, Amino acids, Organic Acids, Sugars, Salt, Nucleotides

• Chemesthesis (touch, heat, cooling, sound)

Sweet Sour Salty Bitter Umami

TASTE

Flavour Chemistry

• Alcohols, Ketones, Aldehydes, Acids, Esters, Thiols, Sulphurs, Phenols, Furans, Pyrazines

AROMA

CITRATE LACTOSE CASEINTRIGLYCERIDE

Galactose Glucose

Tagatose-6-P Glucose-6-P

Dihydroxyacetone-P Glyceraldehyde-3-P

Pyruvate

Diacetyl

Acetoin

Oxaloacetate

Acetate

Vía Leloir

Acetaldehyde

Ethanol

Hydroxy acids

Ácid

β-ketoacids

Peptides

Amino acids

TransaminationDehydrogenation

DecarboxylationReduction

Aldehydes Alcohol Organic acid Aromatic

Secondary alcohol

Methyl ketones

Lactone

Alcohols

Esters

• Biochemistry of cheese ripening

Free fatty acids

Lactate

Flavour Chemistry

Flavour Chemistry

• Aromas from Metabolism of free amino acids

Phenylalanine

Tyrosine

Trypt

opha

n

Methionine Isoleucine

Valine

Leucine

Flavour Chemistry

• State of the Art Flavour Chemistry Facility GCMS

Systems

Euro Award

Flavour Chemistry

• Automated Volatile Extraction/Concentration• Passive Headspace Technique

• Solid Phase Micro-Extraction (SPME)

Flavour Chemistry

• Automated volatile Extraction/Concentration• Dynamic Headspace Technique

• In Tube Extraction (ITEX)

Sample tube

SampleAir space

Pump

Flavour Chemistry•Dynamic Headspace

Technique•Thermal Desorption (TD)

Sample Grab – Pack Sampling

Flavour Chemistry

• Advanced Gas Chromatography Mass Spectrometry• Single & Triple Quadrupole MS Detection

Flavour Chemistry

• Advanced Gas Chromatography Mass Spectrometry

Flavour Chemistry

Cheddar

Danish Blue

Emmental

Urine Fl

oral

Buttery

Woody

Cheesy

Orange peel/Citrus/Floral

Sweet/tallow

Mushro

om-lik

e

Alcoho

l/Frui

ty

Chocolate/Green

Cabbage/Stink Bomb

Earthy/Musty

Caramel/Toffee

Vinegar

Flavour Chemistry• Odour Activity

• Detection Frequency• ~12 untrained panellists• Record duration of each odour plus description• No of detections x duration = Nasal Impact Frequency (NIF)• Resultant Aromagram

• Bigger the rectangle the more important the compound(s)

Chromatogram Aromagram

Woody/Earthy/bark/cresol

Vinegar

Cheesy/socks

cabbage

Caramel/Toffee

Citrus/orange peel

Odour Descriptors

• Sensory & Flavour Chemistry• Identify the key components responsible for

perception• A Chemometrics Approach

• Associations between sensory attributes and volatiles

Flavour Chemistry

Flavour Chemistry• Examples of On-going Dairy Studies

• Flavour potential of lactic acid bacteria• Flavour characterisation:

• cheeses, yoghurts, whey• Preference Mapping in Cheddar cheese• Assessment of volatiles in milk and dairy

produce from cows feed on grass• Reduced fat yoghurts/cheeses• Indices of auto-oxidation in dairy powders

• Flavour Profiling• Product Matching• Identification of key

odorants• Stability studies

• Oxidation• Identification of off-

odours• Identification of chemical

contaminants

Flavour Chemistry

• Service• Consultancy• Contract

Research• Collaborative

ResearchDr Kieran KilcawleyT: 025 42245kieran.kilcawley@teagasc.ieflavour.chemistry@teagasc.ie