flavour formation in high-quality naturals-rev

7/27/2019 Flavour Formation in High-quality Naturals-rev

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Mario R. FERNANDEZ ALDUENDA4th International Conference on Arabica NaturalsBelo Horizonte, MG, Brazil, 11-12 Sept. 2013


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Outline of presentation

1. A summary of what we know about naturals flavour.2. A study about the effect of fermentation in naturals

flavour.

3. What needs to be addressed about naturals flavour.


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Market

Final product

Roasting

Secondary

processDrying

Primary processGenetics

Environmentalfactors

Farmingpractices

Harvestpractices

Production

The big picture

Raw material(coffee cherry)

Chemical changes Flavour

Physiologicalchanges

Fermentative andother changes


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Production Origin

Quality-Geographyinteractions in MG

(Barbosa, J. N. et al., 2012).

Varieties

Best varieties using clothstrip-picking in BR(Pereira, M. C. et al., 2010).

Ripeness Fingerprinting of different

ripeness stages(Amorim, A. C. L. et al., 2009).

Amino acid profiles ofunripe coffee, dry cherry

(Dias, E. et al., 2012).



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Drying

Quality indicators,(Borem et al., 2008; Coradi et al., 2008; Coradi et al.,2007).

Microscopic cell structure,(Saath et al., 2010).

Rest periods,(Isquierdo et al., 2012).

Location, sun drying

methods, variety andcherry drying layerthickness,

(Berhanu et al., 2012).


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Cherry physiological changes innaturals Oxidative stress

(Rendn, M. et al., 2013).

Seed germination processes,(Bytof, G. et al., 2007; Selmar, D. et al., 2006; Bytof, G.et al., 2005; Selmar, D. et al., 2001).



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Fermentation in naturals and otherchanges Endophytic bacteria in

coffee,(Vega, F. E. et al., 2005).

Fermentation in naturalcoffees,

(Silva, C. F. et al., 2000; Silva, C. F. et al., 2008).

Fermentation andnaturals flavour,

(Diaz Pineda, H. M. and M. R. Fernandez Alduenda,

2007).

Enzymatic and non-enzymatic browningduring drying???



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How the process changes expresschemically Maillard precursors

different to washedcoffees,

(Arruda, N. P. et al., 2012; Knopp, S. et al., 2006; Bytof,G., et al., 2005).

What happens during roasting? Polysaccharides profile,

(Tarzia, A. et al., 2010).

Specific odorants relevant

in naturals? -Damascenone?

(Czerny, M. and W. Grosch, 2000).

Raspberry ketone?(Akiyama, M. et al., 2008).

Chemicalchanges


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What is the expression of naturalcoffees in the cup? Full body,

(Vincent, 1987).

Fruitiness,(Fernandez Alduenda, M. R., 1995; FernandezAlduenda, M. R. et al., 2010).

What else?! What is the market

viewing as New Naturals? Exotic and complex;

spicy, fruity , aromaticand maybe slightlyfermented?

(Madsen, M. P., 2011).

Flavour


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Present research.

Fernandez Alduenda, M.R., Birch, J.,Silcock, P. and Lusk, K.

Department of Food Science,University of Otago,

Dunedin, New Zealand.


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A work in progress Two sets of samples:

1. International setNatural coffee samplesfrom different origins.

Includes washed coffeefrom the same farms.

2. Field work setDifferent natural

process treatmentsfrom same rawmaterial. Includeswashed as witness.

Analyses completed: Descriptive cupping

(three different panels).

Volatiles in green bean

headspace (PTR-MS).

Analyses to be completed:

Volatiles in roasted beanheadspace (GC-O/MS).

Descriptive sensoryanalysis,


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International set 34 samples from 8

countries

Brazil (5)

Colombia (4)

Dominican Republic (2)

Ethiopia (1)

Guatemala (1)

Mexico (9)

Nicaragua (11)

Panama (1)

25 naturals

9 washed from same

farms


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Qualitative data: Free commentsanalysis from cupping

Black currant, spicy pepper, malt fresh lively taste withnicer fruity acidity, good body, complex flavours.

Descriptor Section Category

Blackcurrant Generic Red fruity

Complex Flavour General bouquet

Fresh Taste Unclassified

Fruity Acidity Sweet-acidGood Body Hedonic

Lively Taste Unclassified

Malt Generic Pyrolytic

Pepper Generic SpicySpicy Generic Spicy

Subgroup BNI BNO

Dry-acid 20% 33%

Medium-acid 0% 33%

Sweet-acid 0% 0%

Astringent 40% 0%Citrus-like 0% 0%

Hedonic 0% 0%

Length related 0% 0%

Phenolic 20% 33%


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Correspondence Analysis

Descriptive cupping panel International naturalsamples

AstringentBitter_taste

Caramelly

Chocolaty

Citrus-like

Complex

Driedfruity Dry-acid

Earthy

Fermented

Floral

Fruity

Fungal

Acid

Long

Medium-acid

Nutty

Past-croppish

Phenolic

Pungent

Pyrolytic

Redfruity

Resinous

Rough_body

Smooth_body

SpicyStonefruity

Sweet-acid

Sweet_taste

ToastyTropicalfruity

Wood

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

-0.05 -0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04

F2(9.08%)

F1 (29.83 %)

Symmetric column plot

(axes F1 and F2: 38.91 %)


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MFA of descriptive and significantPTR-MS mass ions

Acidity Intensity

Body Level

Break

Dry

Astringent

Bitter_tasteCaramelly

Chocolaty

Citrus-like

Complex

Driedfruity

Dry-acid

Earthy

Fermented

Floral

Fruity

FungalLong

Medium-acid

Nutty

Past-croppishPhenolic

Pungent

PyrolyticRedfruity

Resinous

Rough_body

Smooth_body

Spicy

Stonefruity

Sweet-acidSweet_taste

Toasty

TropicalfruityWood

Vegetable

26

27

28

29

30 31

3334

35

36

37

394041

42

43440

m/z 45.0

474849

51

52

53

54

55

56

57

58

6162

65

6768

69

71

72

7374

m/z 75.076

79

80

8182

84

85

8788

8990

93

95

9798

99

101103104105

107

110

111

113

114115117

m/z 124.0125131

137

138

147151

153

157

-1

-0.75

-0.5

-0.25

0

0.25

0.5

0.75

1

-1 -0.75 -0.5 -0.25 0 0.25 0.5 0.75 1

F2(10.02%)

F1 (33.29 %)


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A close-up to an MFA section

Sweet-acid

Tropicalfruity

RedfruityMedium-acid

Fermented

Fruity

Long

Floral

Acidity Intensity

Break

Body LevelDry

3-Methyl-2-buten-1-ol, 2E-butenoic acid, 3-methyl butanal, 2,3-butanedione

m/z 88.0

Acetaldehyde

m/z 97.0

m/z 67.0

m/z 53.0

m/z 131.0

m/z 98.0

m/z 89.0

m/z 74.0

m/z 73.0

m/z 90.0

m/z 75.0

m/z 76.0m/z 55.0

m/z 110.0

m/z 44.0m/z 43.0

m/z 82.0

m/z 61.0m/z 62.0

m/z 56.0

m/z 81.0

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

y

x

Descr Inte Ion

Acetaldehyde, highly significant for process, correlated with fermentation degree in coffee:Rodriguez, D. B., et al. (1969).


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Bacteria growth along drying

Code Treatment

21

Bact

Outdoors. Mesh raised table. Thin

layer. Frequent turn-up.22

Bact

Outdoors. Mesh raised table. Thick

layer. Little turn-up.

23

Bact

Honeyed in a bucket outdoors for

two days. From the third day, mesh

raised table, thin layer with frequentturn-up.

1.0E+04

1.0E+05

1.0E+06

1.0E+07

1.0E+08

1.0E+09

0 2 4 6 8

CFU/Cherry(Log)

Drying Day

Bacteria count

21 Bact

22 Bact

23 Bact

Sampled from cherry surface.Count on WL Differential medium @25C.


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PTR-MS analysis of green coffeeheadspace

m/z 27.0

m/z 29.0

m/z 31.0

m/z 33.0

m/z 34.0

m/z 35.0

m/z 37.0m/z 38.0

m/z 39.0

m/z 40.0

m/z 41.0

m/z 42.0

m/z 45.0m/z 46.0

m/z 47.0m/z 48.0m/z 49.0

m/z 51.0

m/z 53.0m/z 55.0

m/z 56.0

m/z 57.0m/z 58.0

m/z 65.0

m/z 69.0

m/z 70.0

m/z 71.0m/z 72.0m/z 73.0m/z 74.0

m/z 75.0m/z 76.0

m/z 80.0

m/z 81.0

m/z 85.0

m/z 86.0

m/z 87.0

m/z 88.0

m/z 89.0m/z 90.0

m/z 91.0

m/z 93.0

m/z 97.0

m/z 98.0m/z 101.0

m/z 103.0m/z 104.0m/z 105.0

m/z 107.0

m/z 117.0

m/z 119.0

m/z 129.0m/z 131.0

m/z 147.0

m/z 153.0

-1

-0.75

-0.5

-0.25

0

0.25

0.5

0.75

1

-1 -0.75 -0.5 -0.25 0 0.25 0.5 0.75 1

F2(7.34%)

F1 (77.39 %)

Variables (axes F1 and F2: 84.73 %)

Active variables

1A

1B

2A

2B3A

3B

4A

4B

5A

5B

6A

6B7A7B

-10

-5

0

5

10

-10 -5 0 5 10 15

F2(7.34%)

F1 (77.39 %)

Observations (axes F1 and F2: 84.73 %)

The mass ions correlated with fruitiness in the international sample study are here correlated to thefermentation intensity in the field study.


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What happens when we look atindividual cupping score results Different cupping schools have

different attitudes toward naturals. Cuppers unfamiliar with naturals or

unaware of the New Naturals trendtend to prefer the cup that mostresembles the washed.

Cuppers familiar with naturalsapparently do not score based just onhow winey they taste.

Some cuppers even reward the

wineyness.

It is risky to make conclusions basedon quality perception. That is why thedescriptive flavour profile must bestudied.

m/z 27.0

m/z 29.0

m/z 31.0

m/z 33.0m/z 34.0

m/z 35.0

m/z 37.0m/z 38.0

m/z 39.0m/z 40.0m/z 41.0

m/z 42.0

m/z 45.0m/z 46.0

m/z 47.0m/z 48.0m/z 49.0

m/z 51.0

m/z 53.0m/z 55.0

m/z 56.0

m/z 57.0m/z 58.0

m/z 65.0

m/z 69.0

m/z 70.0

m/z 71.0m/z 72.0m/z 73.0m/z 74.0

m/z 75.0m/z 76.0

m/z 80.0

m/z 81.0

m/z 85.0

m/z 86.0

m/z 87.0

m/z 88.0

m/z 89.0m/z 90.0

m/z 91.0

m/z 93.0

m/z 97.0

m/z 98.0m/z 101.0

m/z 103.0m/z 104.0

m/z 105.0

m/z 107.0

m/z 117.0

m/z 119.0

m/z 129.0m/z 131.0

m/z 147.0

m/z 153.0

-1

-0.75

-0.5

-0.25

0

0.25

0.5

0.75

1

-1 -0.75 -0.5 -0.25 0 0.25 0.5 0.75 1

F2(7.34%)

F1 (77.39 %)

Variables (axes F1 and F2: 84.73 %)

Panel 1 Panel 2 Mass ions


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In brief Flavour formation in naturals is highly complex and at least

three independent mechanisms can be happening: Fruit and seed metabolism.

Fermentation.

Enzymatic and non enzymatic browning (as in raisins). Limited research on the effect of these mechanisms on the

final cup profile has been completed.

Cuppers results are always subjective, but become more

polarised and controversial for naturals. However, even the cuppers that dislike naturals can be used

for descriptive cupping.


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Insights and research agenda proposal about high-quality naturalsflavour.


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Coffee is about flavour Arabica naturals have often

been misunderstood by theindustry and researchers. Confusion between flavour

and quality.

Generalisation: A and B are natural.

A has a characteristic (badquality, wineyness, good

body) Ergo B has it too!

Absence of links of differentstudies to cup flavour.

Cupflavouris and must be

the main way to interpretcoffee : The chemical and

biochemical mechanisms

behind it. The market and consumer

behaviour around it.


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There can be a sensory space foreveryone Experience shows us there are

many natural coffee styles. Someexamples: Caramelly Chocolaty Red fruity

Tropical fruity Dried fruity Winey Cognac/whiskey -like

Why dont we acknowledge themand try to excel in each of them,instead of quarrelling about whichone is better quality?

Beer styles charthttp://www.howtobrew.com/section4/chapter19-1.html


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Consumer

Market

Final product

Roasting

Secondary

processDrying

Fermentation

Primary process

Genetics

Environmentalfactors

Farmingpractices

Harvestpractices

Production

Ultimately, it is about connectingthe dots


Chemical changes

Chocolaty style

Fruity style

Winey style




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Directions for future research Effect of varieties on natural coffee flavour.

Characterisation of different varieties pulp and mucilage. Effect of overripe cherries or dried-on-tree cherries on flavour. Role of enzymatic browning on flavour. Role of non-enzymatic browning along drying. Effect of selected wild microbial populations on flavour. Effect of specific inoculates on flavour. Fate of the main precursors found in naturals during roasting. Characterisation of natural coffee styles. Perfection of different styles. Characterisation of different market preferences and trend about

naturals. Characterisation of the consumers of high-quality naturals.


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Naturalmente!


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flavour formation in high-quality naturals-rev

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