USE OF A SOAKING PROCEDURE TO IMPROVE DRY BEAN ATTRIBUTES - MILESTONE 7 pdf

It has also been demonstrated that soaking of beans in water, after fermentation, leads to dried cocoa with higher brown bean percentages, lower shell content and improved flavour charac

013/VIE05: FERMENTATION AND DRYING TRIAL AT NLU September, 2007

ATTACHMENT TO MILESTONE 7 REPORT

TRIAL TITLE: “USE OF A SOAKING PROCEDURE TO IMPROVE DRY BEAN ATTRIBUTES”

Introduction:

It is generally understood that the length of fermentation has an effect on the quality attributes of cocoa

Attributes affected include shell content, pH, titrable acidity (TA), cut test results and flavour attributes It has also been demonstrated that soaking of beans in water, after fermentation, leads to dried cocoa with higher brown bean percentages, lower shell content and improved flavour characteristics, (Hollywood, N W 1997) This trial was undertaken to demonstrate whether the effects of fermentation time and soaking were applicable

to Vietnamese cocoa

Materials and Methods:

The factors mentioned in the introduction led to the conduct of a fermentation where sub-samples were taken for drying on days five, six and seven of the fermentation These sub-samples were then divided into two with one half being soaked in water for two hours before placement on the dryer The other half was placed directly

on the dryer This lead to 6 dried bean samples being generated as follows:

1 Five days fermented un-soaked

2 Five days fermented plus soaked

3 Six days fermented un-soaked

4 Six days fermented plus soaked

5 Seven days fermented un-soaked

6 Seven days fermented plus soaked

Pods were a mixture of clones and hybrids from Dak Lak and stored for eight days prior to breaking Beans were also spread, in an indoor area for four hours, prior to being placed in the fermentation box This

spreading procedure led to an 11.98% moisture loss After spreading, 95.5kg of wet beans were left and these were fermented in a wooden box at 45cm bean depth, for seven days Sub-samples were taken on days 5, 6 and 7 These beans were then treated as listed above and dried on a solar dryer at Nong Lam University Beans were turned, in the boxes, on days two and four Temperatures of the fermentations were taken from the top, middle and bottom of the fermenting boxes on a daily basis

On each day of the fermentation, samples of fermenting beans were taken for measurements of pH and titrable acidity of the cotyledon and pulp/testa Dry beans were subjected to the tests of pH, titrable acidity, shell content, moisture, cut test and sensory evaluation

All tests were conducted as per the CARD Cocoa Analysis Manual

Results and Discussion:

The temperature of the fermentation, on various days, is presented in figure 1 Temperatures encountered were fairly typical with a decline in temperatures from day three onwards indicating that the fermentation may only need to have been conducted for four or five days

Figure 2: pH of bean components during fermentation for treatment WS1

Typically, during a cocoa fermentation, pH values of the different components equilibrate by the end due to a diffusion of organic acids through the cotyledon from the pulp/testa The rise in pH of the pulp is slower than usual otherwise trends demonstrated in this fermentation could be considered as fairly typical of a cocoa fermentation

DRIED BEAN ANALYSIS

During the fermentation trial, samples were taken from the fermenting box on days 4, 5 and 6 and then divided for soaking and un-soaked In this way, an effect of fermentation time, as well as soaking could be noted The effect of the different treatments on the pH of the resultant dried cocoa is presented in figure three

pH Dried Bean components

Figure 3: pH of dried bean components taken on days 5, 6 & 7 of

the fermentation

Figure three demonstrates a higher pH of the nib, due to soaking, on each day of the fermentation sampled

pH values tended to decrease with length of fermentation time West African cocoa usually has a pH of around 5.1 The results indicate that a fermentation period of five days, with the soaking procedure, could be suitable for producing a West African type cocoa

Titrable Acidity Dried Bean components

Percent Brown Beans in Cut Test

Figure 5: Fully brown bean percentage in cut test results for each treatment

Figure five demonstrates a dramatic effect of soaking on the fully brown bean percentage Under the current buyer preference for high brown bean counts, this treatment could be strongly recommended as long as flavour attributes are not adversely affected

Percent Purple/Brown Beans in Cut Test

Figure 6: Partly brown bean percentage in cut test results for each treatment

Figure 6 demonstrates an almost inverse relationship between fully brown beans and partly brown This indicates that a high proportion of beans which would be partly-brown without soaking, become brown with soaking Purple beans (2%) occurred only on day 5 of the un-soaked beans and this is not presented

graphically

Shell content of dried beans

Percentage shell Content

Figure 8: The effect of soaking fermented beans, prior to drying, on shell content

Figure 8 demonstrates that the shell content of beans which have been soaked in water, prior to drying is less than that of beans which haven’t been soaked Again this is desirable from the industry stand point as shell is

a waste product

Summary

Results presented indicated that the desirable attributes of less acidity, higher brown bean percentages and less shell were obtained by using the soaking procedure Sensory analysis of samples was not conducted There is a need to confirm whether the soaking procedure produces cocoa closer to the West African

standard

References:

N Hollywood “The effect of fermentation time and washing of cocoa prior to drying on cocoa quality in Papua New Guinea” Cocoa Growers Bulletin, 1997

FERMENTATION AND DRYING TRIAL CARD 05VIE013 NLU DECEMBER, 2007

ATTACHMENT TO MILESTONE 7 REPORT

TRIAL TITLE: Comparison of fermentations conducted using stored and un-stored pods, bean

spreading prior to fermentation, bean washing post fermentation and box and heap fermentations Introduction:

Fermentation trials conducted at WASI in April 2007 had indicated that spreading of beans prior to

fermentation led to more rapid temperature increases and higher brown bean percentages in cut test results A previous trial, conducted at WASI, had indicated that more rapid temperature increases, during fermentation, and higher brown bean counts resulted from storage of pods, for one week, prior to fermentation The practice

of soaking beans in water, at the end of fermentation and prior to drying was also conducted at Can Tho

University in April 2007 and Nong Lam University in September 2007 These trials had demonstrated higher brown bean counts and less acidity and shell content were obtained by soaking beans prior to drying

Sensory testing was conducted on the dried bean samples from WASI at Nong Lam University (NLU) in December 2007 and the results were inconclusive as to whether the practices of bean spreading, pod storage and fermentation in a hot house led to improved cocoa flavour As regards pod storage and bean spreading, trials conducted in Malaysia have indicated improved flavour resulting from both practices (Biel, 1987)

In Vietnam, cocoa buyers generally pay a premium for beans with the highest brown bean counts Therefore the practices of pod storage and bean spreading were tested again at NLU in December 2007 Heap fermentations and box fermentations were also conducted to note any differences between the two fermentation methods The practice of soaking of beans in water for two hours prior to drying was applied to each fermentation treatment

as this also leads to higher brown bean counts (Hollywood, 1997)

Materials and Methods:

Pods were obtained from the WASI plantation, as insufficient pods were available at NLU, and transported by truck to NLU The following fermentation treatments were conducted:

Treatment 1: Box fermentation of 100kg of beans from fresh pods

Treatment 2: Box fermentation of 100kg of beans from pods stored for 7 days

Treatment 3: Box fermentation of 100kg of beans from pods stored for 7 days and spread in sun for 3 hours prior to placement inboxes

Treatment 4: Heap fermentation of 100kg of beans from pods stored for 7 days

Treatment 5: Heap fermentation of 100kg of beans from fresh pods

All treatments had sub-samples taken for drying on days 4, 5 and 6 These sub-samples were each divided in two with one half being soaked for 2 hours in water (S) and the other un-soaked (U) This led to the following list of dried bean samples:

Table 1: List of dried bean samples generated during fermentation trial

Dried bean sample Fermentation and drying treatment

T1D 4 U Fermentation treatment 1 dried day 4 without soaking

T1 D 4 W Fermentation treatment 1 dried day 4 with soaking

T1 D 5U Fermentation treatment 1 dried day 5 without soaking

T1 D 5 W Fermentation treatment 1 dried day 5 with soaking

T1D 6 U Fermentation treatment 1 dried day 6 without soaking

T1 D 6 W Fermentation treatment 1 dried day 6 with soaking

T2D 4 U Fermentation treatment 2 dried day 4 without soaking

T2 D 4 W Fermentation treatment 2 dried day 4 with soaking

T2 D 5U Fermentation treatment 2 dried day 5 without soaking

T2 D 5 W Fermentation treatment 2 dried day 5 with soaking

T2D 6 U Fermentation treatment 2 dried day 6 without soaking

T2 D 6 W Fermentation treatment 2 dried day 6 with soaking

T3D 4 U Fermentation treatment 3 dried day 4 without soaking

T3 D 4 W Fermentation treatment 3 dried day 4 with soaking

T3 D 5U Fermentation treatment 3 dried day 5 without soaking

T3 D 5 W Fermentation treatment 3 dried day 5 with soaking

T3D 6 U Fermentation treatment 3 dried day 6 without soaking

T3 D 6 W Fermentation treatment 3 dried day 6 with soaking

T4D 4 U Fermentation treatment 4 dried day 4 without soaking

T4 D 4 W Fermentation treatment 4 dried day 4 with soaking

T4 D 5U Fermentation treatment 4 dried day 5 without soaking

T4 D 5 W Fermentation treatment 4 dried day 5 with soaking

T4D 6 U Fermentation treatment 4 dried day 6 without soaking

T4 D 6 W Fermentation treatment 4 dried day 6 with soaking

T5D 4 U Fermentation treatment 5 dried day 4 without soaking

T5 D 4 W Fermentation treatment 5 dried day 4 with soaking

T5 D 5U Fermentation treatment 5 dried day 5 without soaking

T5 D 5 W Fermentation treatment 5 dried day 5 with soaking

T5D 6 U Fermentation treatment 5 dried day 6 without soaking

T5 D 6 W Fermentation treatment 5 dried day 6 with soaking

Beans were fermented for six days, with one turn on the second day and with sub-samples being taken, from each treatment, on days 4, 5 and 6 These beans were placed in a solar dryer and were then subjected to physical and chemical testing using standard methods Temperatures of the fermentations were taken from five positions

in the top, middle and bottom layers of the fermenting boxes at 8AM, 12 noon and 4PM each day of the

fermentation The five temperature measurements for each layer were then averaged for each fermentation treatment The temperature values presented are the averages of those encountered at noon

Samples of fermenting beans were taken for measurements of pH, titrable acidity and moisture of whole beans, cotyledon and pulp/testa on days 4, 5 & 6 of the fermentation Weights of 50 beans and the bean components of cotyledon and pulp/testa were also conducted Dry beans were subjected to the tests of pH, titrable acidity, moisture, shell content and cut test

Results and Discussion:

Figure 1: Temperatures of fermentations during the six day fermentation period

The fermentation temperatures encountered are unusual in that there is not an accelerated fermentation occurring due to pod storage or spreading of the beans in the sun prior to fermentation This is in distinction to results obtained at WASI and to other trials conducted in Vietnam or reported from countries such as Malaysia and Indonesia All treatments, including both box and heap fermentation methods followed a very similar pattern and reasons for this are not immediately apparent

Moisture % Whole Beans

Figure 2: Moisture content of whole beans during the six days of fermentation

As would be expected, the highest initial moisture contents occurred in the fresh beans of treatments one and five Pod storage led to lower initial moisture contents in treatments two and four The lowest moisture content occurred in the beans which had been subjected to pod storage and bean spreading (treatment 3) However as the fermentation progressed, differences in moisture content were not consistent The treatments which

generally had the lowest moisture content were two and three but this was not reflected in temperature profiles which could be expected to be higher in these treatments All treatments had decreasing moisture levels as the fermentations progressed This would be due to drainage from the boxes and heaps together with evaporation

Weight 50 Whole Beans (g)

Figure 3: Weight of 50 whole beans during the six day fermentation

Differences in initial bean weights would be mainly affected by the practices of pod storage, during which moisture loss occurs and bean spreading, where moisture drains off On day one, the weight of whole beans was

as could be expected, with fresh beans of treatments one and five having the highest weights, treatments two and four being intermediate and treatment three having the lowest weight

However, as the fermentation progresses the distinction is not so clear and bean weights do not necessarily correspond with moisture levels This may be due to inherent variability in bean sizes

Figure 4: Weight of 50 cotyledons during the six day fermentation

Differences in whole bean weights were not reflected in kernel weights This is probably due to the fact that most of the differences in whole bean weights are due to loss of moisture from the pulp There is a general tendency for cotyledon weights to increase with length of fermentation time This may be due to an uptake of moisture from the pulp to the cotyledons

Figure 5: Weight of 50 pulp/testa during the six day fermentation

As with whole bean weights, pulp weights on day one, reflect the treatments given to beans Beans from fresh pods (T1 & T5) have the highest pulp weights Beans from stored pods (T2 & T5) have lower pulp weights due

to evaporation during storage and beans subject to pod storage and spreading (T3) have the lowest weights As the fermentation progresses, there is a general downward trend This would be due to drainage during

fermentation Treatments four and five show the lowest pulp weights by the end of the fermentation and this may be due to greater drainage of moisture from the beans than that in the box fermentations

Figure 6: Kernel to pulp ratio during the six day fermentation

In an inverse relationship with pulp weights, kernel to pulp ratios are the lowest for fresh pods (T1 & T5), intermediate for stored pods (T2 & T4) and lowest for stored pods and spread beans (T3) Similarly, by day six, the heap fermentations (T4 & T5) have the highest kernel/pulp ratios

Figure 7: pH of bean components during fermentation for treatment one