ASSESSING THE IMPACT OF A MIXED SOLAR DRYER ON THE QUALITY OF HEAP FERMENTED COCOA BEANS

ABSTRACT
Ghana has a high reputation in the world market for producing cocoa beans of premium quality. However, the drying of the cocoa beans comes with intense labour and high losses due to the deterioration of beans during processing. Solar drying technology has the potential to reduce postharvest loses. The use of this technology in Ghana is very limited among cocoa producers and the need to explore its comprehensive value has become imperative. This research study aimed to primarily assess whether solar drying technology enhances the organoleptic properties of cocoa beans using heap fermentation.
Proximate, Free Fatty Acid (FFA), Titratable Acidity, Vitamin C and pH, according to the recommendations of AOAC were determined. Air temperature and relative humidity readings were taken after the cocoa sample had undergone complete heap fermentation for six days. An initial moisture content of 51% was recorded for the freshly fermented samples and put through two treatments: solar and open sun drying systems. The moisture content reduced to 6.0 % for the solar dried sample after the third day and 7.0% for the open sun dried sample after the sixth day. Data collected were subjected to statistical analysis. The findings reveal that solar dried cocoa beans generally had higher crude protein, crude fibre, total carbohydrate, and lower raw fat, ash content as compared to that of the open sun dried sample. There were no defects recorded for the cut test, however percentage purple was lower for solar dried compared to the open sun dried.
The percentage proportions of each of the sensory descriptors assessed by the panelist scored higher in favor of open sun dried cocoa beans. In conclusion, the open sun drying system was better to process cocoa products of good quality in terms of the sensory test but the solar dryer had a shorter drying time.

CHAPTER ONE
1.0 INTRODUCTION
1.1 Background to the Study
Cocoa is mainly produced in West Africa representing about 72% of the world cocoa production. The four major West African countries that are main producers of cocoa are Côte D’Ivoire, Ghana, Nigeria, and Cameroon. Pacific Asia area accounts for about 15% and America is 13% of the 3.5 million tons cocoa beans produced world over (Knight, 1999). Cocoa is one of the precious cash crops countries depend on for foreign exchange. Ghana is reported to be one of the major producers of cocoa among other countries with production estimated at 700,000 tons annually followed after Cote D’Ivoire. Ghana is known to be the world's leader in the aspect of quality cocoa beans due to the proper methods used during the processing of cocoa beans after harvest.

The cocoa industry forms a greater share of the nation’s labour force, by employing over 60 percent of all the farmers in the country (Appiah, 2004). Farmers enjoy about 70-100% of their annual household income from cocoa cultivation; improving the standard of living of these farmers is a major concern of the government aimed at increasing the country’s production and processing of quality cocoa beans into semi-finished and finished cocoa products for local consumption and exports (Awua, 2002).

There are various post-harvest processes undertaken to maintain cocoa bean quality, these include harvesting, breaking of the pods, fermentation, drying, and packaging. The cocoa beans start fermenting immediately it is broken and removed from the pod. The bean is exposed to several microbial activities from lactic acid, yeast, bacteria and acetic bacteria which advance to forming different range of metabolic end products, which are mostly precursors for the formation of cocoa flavor. Cocoa bean is the main raw material for manufacturing chocolate; therefore good and quality cocoa is required to produce the needed cocoa ingredients like cocoa butter, powder and liquor (Ardhana and Fleet, 2003).

Drying is initiated when fermentation of cocoa is complete; it is part of the continuous process which ensures the complete fermentation of the cocoa beans and this process usually includes oxidation. It usually enable most of the chemical transformation to take place to ensure continuation of the formation process in order to limit the bitterness and enhance the flavor. Drying is supposed to decrease the water content which is usually about 55% to 7.5% (wb) necessary for reduced transportation and shipment cost, prevent microbial contamination and thus extend the shelf life of the beans and make it safe for storage, shipment and further processing into the chocolate (Afoakwa et al., 2008).

Drying of cocoa beans can be done in two ways; either by artificial or sun drying. Sun drying is the traditional method which is widely used and believed to be the most effective way of producing quality cocoa beans, although this method comes with its own shortfalls. Cocoa beans are mostly dried on bamboo mats in Ghana, these mats are usually supported by shorter wood frames which raise the platforms above lower grounds. These mats have been designed such that, they can be rolled up to cover the beans after sunset to protect it from bad weather conditions over the night. A comparison by Manoj et al. (2013) on both open Sun and Solar drying revealed that solar drying technology has more advantage over the former, such that beans are able to dry in a shorter time and also produce more quality and hygienic beans with less foreign material such as stones, broken sticks, dead insect remains and insect pest droppings.

Also a study by Nguyen (2007) showed that solar driers are suitable for all weather in the whole year round especially in the rainy season, the drying time of cocoa, which is usually longer than 10 days was reduced to about 6-7 days using solar drying. Therefore, over fermentation (rotten stage) was avoided as well as mould contamination and development of smoky off-flavours as fermented produce are in enclosed structures where the temperature of air surrounding the produce is usually higher than the temperature in the dryer.

1.2 Problem Statement
The irregular drying process, which is usually dependent of weather conditions coupled with nightfall, affects the bio-chemical reaction and colorization of the beans. Though this is a very simple method by which cocoa beans are dried in open sun, the drying time is dependent on climatic conditions and temperature. During the rainy seasons, there are prolonged drying times for about two to three weeks and re-wetting of cocoa beans causing the moisture contents to be over 8%. Incomplete drying due to inadequate or very low temperatures disrupt the drying process and fails to reduce moisture level to the accepted standard. This could result in the development of moulds, high concentration of flavor carbonyls which can lead to mouldy/musty beans, unpleasant flavors and the potential Ochratoxin A (OTA) production among the beans which has to be further stored and later dispatched (CAOBISCO, 2015).

1.3 Justification
With increase demand by clients and processing companies all over world for improved quality of cocoa beans and being productive by using cocoa beans that are free from smoky off-flavours especially PAH, free from external and internal moulds, free from adulteration and debris. As a result, a solar dryer with thermal energy was contemplated, the storage is set to give the thermal inertia that will be able to aid the solar collector throughout the seasons of unfavorable weather conditions as well as sunset; and in addition make available the required impedance against moisture re-absorption during the rest period (Fagunwa, 2009).

1.4 Main Objective
This study is aimed primarily at assessing whether solar drying technology enhances the quality of cocoa beans over the open sun drying under ambient conditions, using heap fermented cocoa beans.

1.5 Specific Objectives
The specific objectives of the study are to:

To use the cut test analysis to determine the effect of the drying methods on the physical appearance of cocoa beans.

To compare the drying times of both solar and open sun drying systems.

To compare the effect of the drying methods on the sensory attributes of the beans.

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Item Type: Ghanaian Postgraduate Material  |  Attribute: 59 pages  |  Chapters: 1-5
Format: MS Word  |  Price: GH50  |  Delivery: Within 30Mins.
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