Farida Adam's results presentation

Effect of Pod Storage and Farm Age on the Biochemical Composition, Fermentative Quality and

Flavor Quality Characteristics of Fermented Cocoa Beans

Presented byFarida Adam

Supervisors:Prof. Emmanuel Ohene Afoakwa

Prof. Agnes Budu

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Introduction Pod storage is a form of pre-conditioning that allows favourable

conditions in the cocoa pod in order to begin the process of fermentation.

Studies have reported that pod storage positively affects chemical composition and aids in the development of the precursors (sugars and proteins) for the characteristic chocolate flavor

Pod storage increases pH and decreases non-volatile acids to levels where cocoa beans have a strong potential for developing higher flavours (Afoakwa et al., 2012

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Main objectiveThe main objective of this study is to investigate the effect of pod storage and farm age on the biochemical composition, fermentative quality and flavor quality characteristics of fermented cocoa beans in Ghana.

Specifically:1. To investigate changes in the chemical constituents, mineral composition, physical and physico-chemical

composition of cocoa beans during fermentation from cocoa farms of different farm (tree) ages.

2. To investigate the effects of pod storage and age of farm (tree) on the biochemical composition (total sugars, reducing and non-reducing sugars, FFA) of fermented cocoa beans

3. To investigate the effects of pod storage and age of farm (tree) on the total polyphenol and anthocyanin content of fermented cocoa beans

4. To investigate the effects of pod storage and age of farm (tree) on the flavour quality characterictics of fermented cocoa beans using sensory and instrumental methods

5. To investigate the effects of age of farm (tree) and pod storage on the fermentative quality of cocoa beans from Ghana

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Sample Preparation• Study sites : Asiakwa and Bosuso in the Eastern region of Ghana (4 Farmers’ farms)

Harvesting (2400 pods)

Pod breaking [1200 pods (aof x ft)]

1200 pods (aof x ps)

Heap fermentation (0,3,6 days)

Heap fermentation 6 days

Pod storage (0,3,7,10 days)

Pod breaking

Sun drying on mats

Storage (jute sacks) Lab analysis

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Methods

Laboratory analysis

Chemical composition Proximate analysis (AOAC 2005 methods)

Physico-chemical composition pH, Titratable acidity (AOAC 2005 methods)

Biochemical composition Free fatty acids (AOAC, 2005) Sugars (Lane and Eynon described by James, 2005)

Polyphenols and Anthocyanins Spectrophotometry

Fermentative quality Cut test, colour, fermentative index

Flavour analysis Descriptive sensory analysis with a trained panel

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RESULTS

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Objective 1

• To investigate changes in the chemical constituents, mineral composition and physico-chemical composition of cocoa beans during fermentation from cocoa farms of different farm (tree) ages

• Methods – AOAC, 2005

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Table 1: Effect of fermentation time on the proximate composition of cocoa beans from farms of different ages

Age of Farm

(years)

Fermentation time (days)

Moisture (%)

Protein (%)

Fat (%)

Ash (%)

Carbohydrate(%)

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0 5.16 ± 0.03 17.35 ± 0.02 51.14 ± 1.19 5.07 ± 0.01 21.28 ± 0.16

3 5.29 ± 0.20 15.40 ± 0.01 48.68 ± 0.86 3.22 ± 0.02 27.41 ± 0.25

6 4.57 ± 0.12 15.17 ± 0.05 48.67 ± 0.89 2.57 ± 0.01 29.02 ± 0.19

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0 4.62 ± 1.02 19.80 ± 0.10 50.89 ± 0.44 4.87 ± 0.03 19.82 ± 0.53

3 5.92 ± 0.07 19.63 ± 0.03 48.12 ± 1.13 3.49 ± 0.03 22.84± 1.05

6 6.65 ± 0.05 16.30 ± 0.02 48.45 ± 1.58 2.50 ± 0.01 26.10 ± 0.88

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0 6.97 ± 1.63 17.88 ± 0.05 49.81 ± 1.11 4.58 ± 0.02 20.76 ± 0.16

3 4.99 ± 0.00 13.48 ± 0.02 49.64 ± 1.69 3.44 ± 0.02 28.45 ± 0.11

6 5.22 ± 0.17 13.83 ± 0.01 46.79 ± 0.46 2.22 ± 0.01 31.94 ± 0.09

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0 5.37 ± 0.13 18.40 ± 0.02 49.68 ± 0.67 4.33 ± 0.05 22.22 ± 0.03

3 5.54 ± 0.05 18.15 ± 0.02 45.57 ± 0.76 3.83 ± 0.05 26.91 ± 0.51

6 6.77 ± 0.51 13.32 ± 0.02 46.49 ± 2.47 2.11 ± 0.01 31.31 ± 0.42

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ANOVA summary table for chemical analysis

Variables Moisture Protein Fat Ash Carbohydrate

Age of Farm (AF) 0.50 3.46 3.14 5.47* 8.24*

Fermentation Time

(FT)

0.15 7.15* 9.65* 63.14 0.23

Interaction (AF x FT) 2.72 1247.05* 0.61 2.74* 3.12*

*Significant at P < 0.05

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Table 2 Effect of fermentation time on the mineral composition of cocoa beans from farms of different ages

Mineral content (mg/100g) ± Standard deviation

Age of Farm (years)

Fermentation time (days) K Mg Ca Cu Fe P

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0 710.00 ± 2.00 1821.00 ± 1.00 13.80 ± 2.00 0.31 ± 0.20 1894.00 ± 3.00 548.00 ± 4.003 950.00 ± 1.00 2438.00 ± 1.00 34.10 ± 5.00 0.50 ± 0.10 1368.00 ± 2.00 499.00 ± 3.006 630.00 ± 1.00 1909.00 ± 2.00 50.00 ± 3.00 0.21 ± 0.11 1182.00 ± 2.00 422.00 ± 3.00

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0 510.00 ± 5.00 2393.00 ± 3.00 37.00 ± 1.00 0.24 ± 0.14 1694.00 ± 2.00 411.00 ± 1.003 860.00 ± 3.00 2481.00 ± 1.00 16.00 ± 1.00 0.70 ± 0.10 1229.00 ± 1.00 333.00 ± 1.006 360.00 ± 2.00 4598.00 ± 2.00 54.00 ± 1.00 0.36 ± 0.20 1347.00 ± 1.00 384.00 ± 1.00

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0 700.00 ± 2.00 2251.00 ± 1.00 27.00 ± 2.00 0.41 ± 0.11 797.00 ± 4.00 740.00 ± 0.003 910.00 ± 2.00 2602.00 ± 1.00 56.00 ± 1.00 0.52 ± 0.02 299.00 ± 5.00 704.00 ± 3.006 750.00 ± 2.00 2482.00 ± 1.00 75.70 ± 1.20 0.39 ± 0.03 508.00 ± 1.00 647.00 ± 3.00

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0 620.00 ± 4.00 1273.00 ± 2.00 33.70 ± 2.50 0.49 ± 0.03 1550.00 ± 5.00 1532.00 ± 2.003 600.00 ± 5.00 938.00 ± 1.00 45.60 ± 2.00 0.10 ± 0.01 1316.00 ± 2.00 1799.00 ± 1.006 580.00 ± 5.00 3624.00 ± 1.00 82.50 ± 1.20 0.40 ± 0.01 915.00 ± 2.00 484.00 ± 1.00

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ANOVA summary table for mineral analysis

Variables K Mg Ca Cu Fe P

Age of Farm (AF) 2.87 1.28 2.71 0.28 24.52* 4.21

Fermentation

Time (FT)

5.60* 2.46 10.96 0.40 12.44 1.34

Interaction (AF x

FT)

1212.02* 291480.93* 30.24* 3.02* 2872.66* 217788.61*

*Significant at P < 0.05

12Fig.1 The effect of farm age and fermentation time on the pH of cocoa beans (nibs)

5 15 25 315

5.2

5.4

5.6

5.8

6

6.2

6.4

0 days3 days6 days

Farm age (years)

pH

13Figure 2: The Effect of Farm age and Fermentation Time on Titratable Acidity of Cocoa Beans

5 15 25 310

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.018

0.02

0 days3 days6 days

Farm Age (years)

Titratable acid-ity(g/100ml)

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ANOVA summary table for pH and TTA

Variables pH TTA

Age of Farm (AF) 1.11 12.30*

Fermentation Time (FT) 5.28* 6.68*

Interaction (AF x FT) 638.63* 0.01*

*Significant at P < 0.05

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Objective 2

• To investigate the effects of pod storage and age of farm (tree) on the biochemical composition (total sugars, reducing and non-reducing sugars, FFA) of fermented cocoa beans

• Methods– Free fatty acids (AOAC, 2005)– Sugars (Lane and Eynon described by James(2005))

16Fig 3:The Effect of Farm age and Pod Storage on Free Fatty Acid Content of Cocoa Beans

0 3 7 100

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

5 years15 years25 years31 years

Pod storage (days)

FFA (%)

Maximum limit (1.75%)

17Fig 4:The Effect of Farm age and Pod Storage on Total Sugar Content of Cocoa Beans

0 3 7 100

10

20

30

40

50

60

70

5 years15 years25 years31 years

pod storage (days)

total sugars (mg/g)

18Fig 5:The Effect of Farm age and Pod Storage on Reducing Sugar Content of Cocoa Beans

0 3 7 100

10

20

30

40

50

60

5 years15 years25 years31 years

pod storage (days)

reducing sugars (mg/g)

19Fig 6:The Effect of Farm age and Pod Storage on Non-Reducing Sugar Content of Cocoa Beans

0 3 7 100

2

4

6

8

10

12

5 years15 years25 years31 years

pod storage (days)

non-reducing sugars (mg/g)

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Objective 3

• To investigate the effects of pod storage and age of farm (tree) on the total polyphenol and anthocyanin content of fermented cocoa beans

• Methods - Spectrophotometry

21Fig 7:The Effect of Farm age and Pod Storage on Non-Reducing Sugar Content of Cocoa Beans

0 3 7 100

10

20

30

40

50

60

70

5 years15 years25 years31 years

Pod storage (days)

Anthocyanin content (mg/kg)

22Fig 8:The Effect of Farm age and Pod Storage on Non-Reducing Sugar Content of Cocoa Beans

0 3 7 100

20

40

60

80

100

120

140

160

5 years15 years25 years31 years

Pod storage (days)

Total polyphenol content (mg/g)

23Fig 9:The Effect of Farm age and Pod Storage on O-diphenol Content of Cocoa Beans

0 3 7 100

5

10

15

20

25

30

35

5 years15 years25 years31 years

Pod storage (days)

O-diphenols (mg/g)

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Objective 4

• To investigate the effects of age of farm (tree) and pod storage on the fermentative quality of cocoa beans from Ghana

• Methods– Cut test– Colour (Hunter Lab)– Fermentative index (Spectrophotometry)

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Table 3 : Effect of pod storage on the cut test of cocoa beans from farms of different age

Age of farm pod storage Deep purple (%) Pale purple (%) Brown (%) Slaty (%) Mouldy (%)

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0 13 15 70 2 0

3 19 12 69 0 0

7 23 16 56 5 0

10 2 18 80 0 0

15

0 7 13 77 3 0

3 0 18 79 3 0

7 6 31 62 1 0

10 0 0 55 1 44

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0 2 1 93 4 0

3 2 6 79 11 2

7 0 5 64 31 0

10 0 5 59 36 0

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0 1 10 89 0 0

3 7 8 85 0 0

7 12 3 85 0 0

10 1 1 29 69 0

26Fig 10:The Effect of Farm age and Pod Storage on the Colour of Cocoa Beans

0 3 7 1024

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5 years15 years25 years31 years

Pod storage (days)

L- value

27Figure 11 : The Effect of Pod storage and Age of Farm on the Fermentative Index of Fermented Cocoa Beans.

0 3 7 100

0.5

1

1.5

2

2.5

3

3.5

4

5 years15 years25 years31 years

Length of pod storage (days)

Ferm

enta

tive

Inde

x

Well fermented cocoa beans

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Objective 5

• To investigate the effects of pod storage and age of farm (tree) on the flavour quality characterictics of fermented cocoa beans using descriptive sensory methods

• Method – Trained sensory panel

29Figure 12: Flavour profiling of Cocoa Liquor by trained sensory panel

colour intensity

aroma intensity

tasteflavour intensity

intensity of after taste

0

5

10

0 days

colour intensity

aroma intensity

tasteflavour intensity

intensity of after taste

0

5

10

7 days

5yrs15yrs25yrs31yrs

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Conclusions• Fat was the highest chemical constituent irrespective of farm age but the younger farms produced

beans of better chemical constituents for chocolate quality as protein, ash and fat decreased with age.

• Younger farms also produced beans with relatively lower pH values (more acidic) by the end of fermentation which are likely to have better flavour quality.

• Irrespective of farm age, FFA levels remained acceptable for up to 10 days of pod storage however there were increases in total and reducing sugars after the 7th day of pod storage. Sugar content was influenced significantly by farm age.

• The fermentative quality was acceptable as fermentative index values were above 1, good brown colour was retained and the highest proportions of brown beans were obtained after 10 days of pod storage irrespective of age.

• Flavour intensity decreased in younger farms after 7 days with aroma and colour intensity decreasing for older farms

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Recommendations

• The influence of individual agronomic practices and farm age on cocoa bean quality should be investigated

• Instrumental flavour analysis should be done to give more information on flavour quality

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Acknowledgement• Supervisors (Prof Afoakwa and Prof. Budu)

• Staff and students of the Nutrition and Food Science Dept (especially, Prof Saalia, Joyce, Nana Serwah Boateng and sensory panel)

• Farmers (Wofa Adam, Wofa Sammy, Wofa Emma and Elder Richard)

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Thank You