Comparative Evaluation of some Physical and Biochemical Quality Attributes of Cocoa Beans Produced in Assin Fosu , Assin Bereku and Nkawie Cocoa Districts of Ghana

Cocoa contributes significantly to the economy of Ghana due to the premium quality it enjoys in the international market. However, the quality of Ghana cocoa is dwindling gradually making buyers raise serious concerns about the negative impact of poor quality cocoa beans on their products. The study was conducted at Assin Fosu and Assin Bereku cocoa districts in the Central region and Nkawie cocoa district in the Ashanti region. The research was field survey, cut test as well as laboratory work. It was a 3 by 2 factorial experiment in completely randomized design with three replications. There were two factors: the first consisted of the various locations (districts) the study was conducted whilst the second factor comprised the varieties of cocoa (Amelonado and ‘Akokorabedi’) obtained from the various locations. The survey report showed that there were differences in postharvest practices by farmers such as turning during fermentation and duration of fermentation. A report from the cut test revealed that the interaction effect between cocoa varieties and the locations were of significant difference for percentage mouldy cocoa beans (p = 0.00) and slaty cocoa beans (p = 0.05) at 5% probability level. For percentage mouldy beans, Assin Fosu District (location) recorded the highest (2.57%) mean value whilst Nkawie cocoa district (location) recorded the least (0.89%). Similarly, the interaction effect between cocoa varieties and the locations for percentage free fatty acid content (p = 0.01) and pH (p = 0.00) was significantly different at 1% probability level. Assin Fosu District (location) recorded the highest (1.22%) mean percentage free fatty acid value whilst Nkawie district (location) registered the least (1.15%). For pH, Nkawie District (location) recorded the highest (5.82) whilst Assin Fosu district (location) registered the least (5.50). Generally, cocoa beans from the various locations (districts) were of good quality since they all fell within the range of Quality Control Company Limited quality standards, however, beans from Nkawie cocoa district were rated as the best in terms of physical and biochemical quality attributes of the beans.


Introduction
The cocoa industry is being faced with the problems of defective and inferior cocoa beans over the years (Afoakwa et al., 2010).The presence of these defects in the cocoa tends to reduce the quality of the cocoa beans.Some License Buying Companies have their cocoa rejected on these defects if it falls beyond the permissible level.These cause them time, space, logistics, labour cost and other resources in reconditioning their rejected consignments (Duguma et al., 2001).There are instances where cocoa change from its original grade to sub-standard due mainly to the presence of some defective beans.
Despite various interventions by players in the cocoa industry, particularly Quality Control Company Limited to clamp down the presence of these defective beans some cocoa districts still record high percentage of poor quality cocoa beans (Amoa-Awua et al., 2007).

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The data f responden from 5 dif Visits wer Districts to be done to

Parameters
Factors such as mouldy beans, slate, insect damaged beans, germinated as well as flat beans were examined through cut test and physically counted each defective beans and expressed each defective type of beans as a percentage.Additionally, chemical qualities of the beans were also measured.

Data Analysis
Data that were received from the field survey were analysed with Excel graph and IBM Statistical Product and Service Solution (SPSS) version 21.The laboratory and cut test results were analysed using student statistics version 9 software to perform ANOVA.Treatment means were separated with LSD at 1% probability level (p = 0.01) for the laboratory work and LSD at 5 % (p = 0.05) probability level for the cut test result.

Intervals for Harvesting Cocoa Pods by Farmers during the Main Season
Generally, in all the locations, the intervals for harvesting cocoa pods by farmers indicated that 48.7% of the respondents (farmers) harvest their cocoa pods fortnightly whilst 32.6% indicated they harvest their cocoa pods monthly.It was observed that 18% of the respondents harvest their cocoa every three weeks.

Objects Used in Breaking Cocoa Pods by Farmers
The survey report showed that 72% of the respondents (farmers) in all the locations break their cocoa pods with blunt objects whilst 28% of the respondents break theirs with sharp objects.Using blunt object would help improve the quality of cocoa beans since the beans would be secured from injury (Osei, 2007)  tation varies a the optimal du ty of cocoa be a period of be spondents that g cocoa beans (Pandey et  It was observed that none of the respondents in Assin Fosu and Assin Bereku Districts practice turning during fermentation.However, 24% of respondents in Nkawie District indicated they do turn their cocoa beans during fermentation.Failure to turn cocoa beans during fermentation could affect the quality of cocoa beans.In enhancing and achieving cocoa beans quality, turning plays significant role in fermentation (Fowler, 2009).Among the reasons stated for not turning included: distance from house to farm is far, do not have time to do it and not aware of the practice.This therefore would mean that cocoa beans from Nkawie District would be of good quality compared to their counterparts in Assin Fosu and Assin Bereku Districts.Turning of cocoa beans aerates the fermenting mass to avoid uneven temperature and oxygen distributions, which intend improve the quality of cocoa beans (Fowler, 1995).

Physical Beans Quality Characteristics
The effect of cocoa varieties on percentage mouldy, slaty, germinated, flat, insect damaged and purity cocoa beans of dried cocoa beans showed that significant differences occurred between Amelonado and Hybrid cocoa varieties for mouldy, slaty, flat, insect damaged and purity cocoa beans.Hybrid cocoa variety recorded the highest (92.80%) purity cocoa beans than Amelonado, which recorded a purity value of 91.90%.Wood and Lass (1985) reported that factors such as slow or inadequate drying of cocoa beans, prolonged fermentation as well as storage of dried cocoa beans under highly humid conditions could lead to mouldy cocoa beans.The authors added that germinated and damaged beans are also prone to becoming mould.Mould produces mycotoxins particularly Ochratoxin 'A' which gives cancer when one consumes any cocoa product.They also cause high level of free fatty acid thereby given the cocoa a bad flavour (Afoakwa et al., 2010).
The cut test result showed that Assin Bereku District registered the highest (4.22%) slaty beans with the least being recorded by Nkawie District (1.72%).The high slaty value recorded by Assin Bereku District could be due to the fact that the farmers do not practice turning during fermentation as realized in the survey.However, this figure was within the permissible level of not more than 8% to be of good quality cocoa beans.Slaty cocoa beans give chocolate a bitter taste and reduce the market value of cocoa (Dand, 1997).Factors that attribute to slaty cocoa beans include lack of fermentation, inadequate fermentation days, lack of turning during fermentation, insufficient fermentation heap size and when the temperature outside the fermentation mass is too low especially during harmattan period (Daviron, 1995).
In terms of variety, Amelonado recorded the highest percentage slaty beans (3.5%), flat (0.92%) and insect damaged beans (0.97%) than hybrid.This could be due to the inherent quality characteristics such as resistance to pests and diseases, ability to withstand extremes of weather and early maturity possessed by the hybrid variety as reported by Osei (2007).
The mean percentage mouldy beans for the interaction ranged from 0.89% to 2.57%.Nkawie district recorded the least (0.89%) mouldy beans whilst Assin Fosu District recorded the highest (2.57%).
Tables 3, 4 and 5 show physical quality characteristics of cocoa beans.

Chemical Beans Quality Characteristics
The effect of locations on fat, FFA, pH, and moisture content of dried cocoa beans revealed that significant deference was observed between the locations and varieties for pH and free fatty acid content (FFA).For fat, Assin Bereku District registered the highest value (43.53%) whilst Assin Fosu District recorded the least (42.65%).In the case of free fatty acid content, Assin Fosu District recorded the highest value of 1.22% with the least value being registered by Nkawie District (1.05%).Free fatty acid occurs because of poor postharvest activities such as the use of black beans from diseased pods, the use of mouldy beans, germinated beans from over ripened pods and the inclusion of decayed beans (Daviron, 1995).Prolonged storage of cocoa beans could also cause an increase in the free fatty acid level of dried cocoa beans.The results further showed that Assin Fosu District registered the highest (1.22%) value of free fatty acid (FFA) with Nkawie District recording the least (1.15%).However, the values recorded were within the European Union requirement of 1.75% to be of good quality cocoa beans (Fowler, 2009).
As per Quality Control Company Limited quality standard, any parcel of cocoa with moisture content above 7.5% is not acceptable.Moisture contents exceeding 8% could lead to mould development inside the beans during subsequent storage and transport.Additionally, cocoa beans with high moisture content could cause beans to germinate under favorable conditions, cause beans to decay and insect infestation.All these factors contribute to high level of free fatty acid, which invariably affects the quality of cocoa beans (Fowler, 2009).
Tables 6, 7 and 8 below provide chemical quality characteristics of cocoa beans.

Conclusion
Respondents (farmers) from the various locations exhibited differences in some postharvest practices such as duration of fermentation and turning of cocoa mass during fermentation.
Generally, cocoa beans from the various locations (districts) were of good quality since they all fell within the range of Quality Control Company Limited quality standards, however, beans from Nkawie cocoa district were rated as the best in terms of physical and biochemical quality attributes of the beans.
There were significant differences between cocoa varieties and the different locations for their percentage mould, slate, flat, insect damaged and purity cocoa beans.
For percentage mouldy cocoa beans, Assin Fosu District recorded the highest value of 2.57% whilst Nkawie District registered the least (0.89%).Assin Bereku District recorded the greatest percentage of slaty cocoa beans (4.22%) with Nkawie District registering the least (1.72%).
The interaction effect between cocoa varieties and the locations for free fatty acid content and pH were of significant difference.Assin Fosu District registered the highest free fatty acid content of 1.22% whilst Nkawie District recorded the least (1.15).For pH, Nkawie District recorded the highest value of 5.82 with the least value of 5.50 being registered by Assin Fosu District.

Recommendations
It is suggested that further studies be conducted at other cocoa Districts in order to identify the postharvest practices of cocoa farmers that affect quality.
In addition, pesticide residue should be carried out to determine the maximum residue levels and types of pesticides used by farmers at the various locations.
those who reviewed the manuscript.Their individual contributions are immensely appreciated.Special thanks also go to the publisher for providing time and space to publish this article to the benefit of the public.

Table 1 .
Duration of fermentation practiced by farmers

Table two
below shows turning of cocoa beans during fermentation by farmers.

Table 2 .
Turning of cocoa beans during fermentation by farmers

Table 3 .
Cocoa varieties and locations on percentage mouldy, slaty and purity cocoa beans

Table 6 .
Interaction of cocoa varieties and locations on pH and percentage free fatty acid content of dried cocoa beans

Table 7 .
Cocoa varieties on fat, FFA, pH and moisture content of dried cocoa beans

Table 8 .
Locations on fat, FFA, pH and moisture content of dried cocoa beans