Brettanomyces Aroma and Flavor Effects Lucy Joseph Department of Viticulture and Enology U.C. Davis.
Flavor and Aroma of Fruit
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1 Flavor and Aroma of Fruits Florence Negre-Zakharov Department of Plant Sciences [email protected] Taste + Aroma = Flavor Taste – perceived in mouth • Sweet • Salty • Bitter • Sour (acid) • Umami (protein – meaty) Taste Receptor Cells on tongue Chandrashekar et al., 2006 Aroma – perceived in nose • Volatile compounds released from various items (food, flowers…) Taste + Aroma = Flavor Small et al., 2005 Orthonasal route Retronasal route Outline • Overview of aroma substances • Methods for aroma measurement - Extraction - Separation - Detection - Analysis • Aroma research linalool OH OH nerolidol linalool OH CH2 OH phenylethanol CH2 O H phenylacetaldehyde OH O OCH3 methylsalicylate linalool OH CH2 OH phenylethanol linalool OH OH geraniol linalool OH CH2 O H phenylacetaldehyde O H benzaldehyde OH OCH3 eugenol limonene limonene linalool OH CH2 OH phenylethanol neral O geranial O
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Flavor and aroma factors in fruit
Transcript of Flavor and Aroma of Fruit
1
Flavor and Aroma of Fruits
Florence Negre-ZakharovDepartment of Plant Sciences
Taste + Aroma = Flavor
Taste – perceived in mouth
• Sweet
• Salty
• Bitter
• Sour (acid)
• Umami (protein – meaty)
Taste Receptor Cells on tongue
Chandrashekar et al., 2006
Aroma – perceived in nose
• Volatile compounds released from various items (food, flowers…)
Taste + Aroma = Flavor
Small et al., 2005
Orthonasal route Retronasal route
Outline
• Overview of aroma substances
• Methods for aroma measurement - Extraction
- Separation
- Detection
- Analysis
• Aroma research
linalool
OH
OH
nerolidol
linalool
OHCH2
OH
phenylethanolCH2
O H
phenylacetaldehyde
OH
O OCH3
methylsalicylate
linalool
OH
CH2
OH
phenylethanol
linalool
OHOH
geraniol
linalool
OH
CH2
O H
phenylacetaldehyde
O H
benzaldehyde OHOCH3
eugenol
limonene
limonene
linalool
OH
CH2
OH
phenylethanol
neral
O
geranial
O
2
Aroma compounds
Terpenoids
Monoterpenes Sesquiterpenes
OH
Farnesol
OH
Geraniol
OH3-hexenol
Fatty acid/amino acid derivatives
Aroma compounds
Fatty acid derivative Amino acid derivative
Isobutyl Acetate
BenzaldehydeEugenol
Phenylpropanoids and Benzenoids
Aroma compounds
Phenylpropanoid Benzenoid
Dimethyl Disulfide
Methyl Anthranilate
N- and S-containing compounds
Aroma compounds
Nitrogen Sulfur
Aroma Measurement
Extraction
Separation
Detection
Analysis
?
Aroma Extraction
• Solvent (alcohol, organic solvents…)
• Steam Distillation
Still
Steam + oil vapors
Condenser (cooling system)
Separator
Essential Oil
Hydrosol (distillate water)
3
Aroma Extraction (cont…)
• Headspace (SPME, dynamic…)
Dynamic closed loop stripping system
Solid Phase Micro Extraction
(SPME)
air
Aroma Separation
• Gas chromatography
GC Oven
GC Column
Sample Inlet
Inte
nsi
ty
Time
HOT
Aroma Detection
• Flame Ionization Detector (GC-FID)
• Mass Spectrometry (GC-MS)
• Olfactory detection (GC-O)
Time
Inte
nsi
ty
Geranyl Acetone
Aroma Analysis
• Quantification (how much “compound x” is in the fruit?)
• Correlation with sensory perception (odor threshold, what does it smell like?...)
Time
Inte
nsi
ty
Quantity
Inte
nsi
ty
Calibration Curve
58.6
26.2 μg
Aroma Analysis and Produce Quality
• Odor thresholds (minimum concentration of a substance at which a majority of test subjects can detect and identify the substance characteristic odor)
• Odor descriptors
Geranyl Acetone fresh, rose, leaf,
floral, green, magnolia, fruity
Time
Inte
nsi
ty
2-Ethyl Hexanolcitrus, fresh,
floral, oily, sweet
Decanal orange peel,
soap
2 ppb270,000 ppb60 ppb
?…
Aroma Research
How are aroma volatiles made in fruits?
What are the impacts of cultural practices and postharvest storage on aroma formation?
How is aroma volatile production regulated in fruits?
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Alcohol Acyl Transferase: a gene involved in melon
aroma formation
Yahyaoui et al., 2002
+ +
Alcohol Acyl-CoA Volatile Ester CoA
AAT
AATs
Regulation of Aroma Formation
Ayub et al., 1996
El-Sharkawy et al., 2005
Regulation of Aroma Formation Regulation of Aroma Formation
• Climacteric fruits
Aroma formation mostly regulated by ethylene, with an unknown ethylene-independent component
• Non-climacteric fruits
Regulation not understood yet (possibility of auxininvolvement?)
Factors Influencing Aroma Formation
• Pre-harvest factors
Supply of carbon (sugars), water stress, light, temperature, biotic stresses…
• Postharvest practices
Ethylene regulation, temperature, biotic/abioticstresses…
Conclusions
Aroma volatiles are a diverse class of plant volatile substances
Many factors influence the aroma quality of fresh produce
Aroma measurement involves extraction, separation, detection and analysis
Aroma quality evaluation is complex!
