1. Introduction
Cocoa is an ancestral crop from Mesoamerica highly valued in developing countries. Cocoa, which is scientifically known as Theobroma cacao L. is primarily cultivated in West African nations such as Ivory Coast and Ghana. The Latin name for the cacao tree, Theobroma cacao L., translates to ‘Food of the Gods’ (Tan et al., 2021). These two countries produce around 60% of the world’s total cocoa. The cocoa is then transported to various countries such as the European Union, Indonesia, the United States and Brazil for processing Cinar et al., 2021.
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Cocoa beans are mainly produced in tropical areas, with a worldwide production of over 4.7 million tons per year. During the 2018-2019 harvest season, Africa, America and Asia and Oceania produced 76.3%, 17.4% and 6.3% of the total production respectively. The exportation of cocoa beans accounts for about 71% of the total volume produced. Although, Europe does not produce cocoa beans, it processes 1.7 million tons of them, which is more than any other continent (Jean-Marie et al., 2022).
The cacao tree is an evergreen with wide branches that grow within 20 degrees of the equator. It prefers warm temperatures (18-21°C – 30-32°C), high humidity (70–100%) and elevations up to 600m. Due to their sensitivity to sunlight and wind, cocoa trees are planted under the shade of taller trees. The standard height of the cocoa tree is maintained at 2–5m on plantations. It produces seedpods called caboose that can grow up to 30 cm long and 10 cm wide. The fruit is harvested twice a year, before and after the rainy seasons. The cocoa pods come in different shapes and sizes and contain 20-50 almond-sized seeds that are about 2 cm long and 1 cm wide. The seeds are surrounded by mucilaginous pulp. (Bertazzo et al., 2013)
Cocoa plants thrive in soil that is deep, well-drained and nutrient-rich. The ideal soil composition for cocoa cultivation is 50% sand for good drainage, 30-40% clay for water and nutrient retention and a balance of 10-20% medium-sized silt. The most suitable soil types for cocoa cultivation are entisols, inceptisols and red or yellowish ultisols and alfisols, which are all rich in minerals and conducive to cocoa growth. Each part of the cocoa plant has its unique composition in terms of quantity and quality. The fruits, which include pods and beans are rich sources of protein, fat and carbohydrates, as well as polyphenols and methylxanthines. They have dark grey-brown bark. Cocoa trees have simple, alternating leaves that are either narrowly ovate or obovate-elliptic in shape. The veins of the leaves are pinnate towards the extremity with a well-marked main vein and prominent secondary veins. The leaves range from 20 to 35 cm long and 6 to 10 cm wide. (Jean-Marie et al., 2022)
Cocoa production generates significant waste. Only 10% of cocoa fruit is used commercially; the remaining 90% is discarded as waste or by-products (Rojo-Poveda et al., 2020). It is worth noting that the entire cocoa fruit, including the husk, shell, and pod, can be utilized to create a wide range of products, such as animal feed, cocoa butter and powder, soft drinks, alcohol, jam, confectionery and cosmetics. Each variety of cocoa provides beans with specific sensorial characteristics that are related to its origin, environmental conditions and fermentation. In this regard, hundreds of volatile compounds, including alcohols, carboxylic acids, aldehydes, ketones, esters and pyrazines have been identified as odour-active components in cocoa. (Cinar et al., 2021)
2. Nutritional composition of cocoa
The fatty acids composition of cocoa beans is of enormous interest for processing and quality control during the manufacture of the product and also because the content of Saturated Fatty Acids (SFA), Monounsaturated Fatty Acids (MUFA) and Polyunsaturated Fatty Acids (PUFA) is a key factor in the health-promoting properties of cocoa. Among the fatty acids detected, stearic acid (C18:0) was the most abundant (37.60%–39.54%) followed by oleic acid (C18:1, n-9) found in the range 30.40%–33.23% and palmitic acid (C16:0) found in the range 24.84%–28.2% (Caprioli et al., 2016). Cocoa beans are widely known to contain proteins that can be hydrolyzed by microorganisms (yeasts, lactic acid and acetic acid bacteria) releasing free amino acids, which can undergo decarboxylase activity by some bacterial enzymes to form amines. 2-Phenylethylamine, tyramine, tryptamine, serotonin, dopamine and histamine have been found in cocoa (Carmo Brito et al., 2017). In addition to nutrients, (carbohydrates, fat, proteins, peptides and amino acids) they also contain bioactive compounds such as polyphenols, including flavanols (epicatechin, catechin, procyanidins), flavanols (quercetin and its glycosides) and phenolic acids (like gallic acid).
The most common types of flavonoids found in cocoa beans are flavan-3-ols, catechins, epicatechins and proanthocyanidins with a higher concentration of procyanidins. Flavonoids are beneficial because they may help improve cardiovascular health, provide antioxidant protection and assist in balancing cholesterol levels in the body. Procyanidins, also known as condensed tannins are made up of dimers, oligomers and polymers of catechins and are responsible for the bitter taste of cocoa (Fang et al., 2020). These compounds (mainly epicatechin, catechin and procyanidins) exhibit a wide range 33 of physiological properties such as antioxidant, antiradical, antimicrobial, anti-inflammatory, antiatherogenic, antithrombotic, antihypertensive, anticarcinogenic and cardioprotective, resulting in the protection against diseases among others such as coronary heart disease, cancer or neurodegenerative disorders. (Żyżelewicz et al., 2018)
3. Processing of cocoa bean
The processing of cocoa beans involves several steps to transform raw cocoa beans into various cocoa products like cocoa powder, cocoa butter and chocolate. Here’s an overview of the typical cocoa bean processing steps. The transformation process steps are first, fermentation of cacao beans followed by removal of water content by drying, then roasting, cleaning and shelling of beans into nibs. Nibs are then ground and refined into cacao liquor before being finally combined with various ingredients to produce different types of chocolate, such as dark chocolate, milk chocolate and white chocolate. (Cinar et al, 2021)
a) Harvesting
Cocoa is a non-climacteric fruit, which means that it does not continue to ripen after it is harvested. Therefore, it is crucial to establish specific parameters to identify the state of maturation. The intrinsic factors, such as the physical properties of the fruit – including size, weight and colour – along with the number, shape and hardness of the cocoa beans are closely related to its maturity level (Mendoza-Meneses et al., 2023).
The harvesting of cocoa fruit has traditionally been based on the knowledge of local collectors. However, several factors like the cultivar, growing conditions, maturity stage and processing can affect the antioxidant compounds in plant foods. Harvesting the cocoa fruit when it’s at an appropriate maturity stage is crucial as it directly impacts the flavour characteristics of cocoa beans. Collecting cocoa beans from unripe fruits results in low sugar content, while overripe ones are susceptible to germination and infection by microorganisms. Furthermore, beans collected from immature or over-ripe fruits may have fewer bioactive compounds than those from fully mature fruits.
Research has shown that blackberries and pepper fruits have the highest antioxidant capacities during their late ripening stages, while the apple and pomegranate fruit’s antioxidant capacities do not differ significantly during their development and ripening stages (Dang et al., 2019). The ideal environmental conditions for cocoa cultivation include a temperature range of 22-28°C, humidity between 70% and 90%, an annual rainfall of 1200-3000mm, nutrient-rich soil containing nitrogen, phosphorus and potassium, with the presence of other essential elements. Additionally, the cocoa plant requires solar radiation exposure of approximately 50% per day and preferential relief on plains or slopes with an efficient drainage system. (Mendoza-Meneses et al., 2023)
b) Sorting
Cocoa beans are sorted based on their size, colour, shape and health. There are three classes of cocoa beans based on size – large, medium and small. The colour of the beans is usually brown, purple or black. The shape of the beans could be oval, round or flat. Healthy beans are sorted from unhealthy, defective or imperfect ones. During sorting, aspects such as clipped, germinated, raw, flat, unfermented, purple, broken, dirt, insect and mouldy beans are considered.
The mouldy type of cocoa beans is a result of wet beans that have germinated and become dry, but the product overgrew leading to the appearance of mold (Brosas et al., 2020). The first step in production is sorting the beans to remove any physical deformities such as broken, clumped, flat and mouldy beans. According to the Bureau of Agriculture and Fisheries Products Standards, broken beans are those with missing fragments or cuts, clumped beans are two or more beans glued together, flat beans have thin cotyledons and mouldy beans have moulds on their outer surface. It is crucial to remove these defects as they can negatively impact the quality of the processed chocolate. However, farmers often rely on visual inspection to remove these defects, which can result in inconsistent and partly incorrect findings, especially when evaluating multiple beans. (Hortinela et al., 2022)
c) Ripening & Breaking
Cocoa pods need to be ripened before they can be used. This can be done by storing them for some time in an open room or in the garden to prevent mould growth. Ripening helps create gaps in the cocoa heaps, which makes it easier for oxygen to penetrate during fermentation.
Cocoa beans can be broken into pieces using either tools or a mechanical process. However, the mechanical process is not commonly used due to the unavailability of the required tools in the market. Additionally, it is quite challenging to use tools to separate the fresh cocoa beans from the broken shells. The use of iron-cutting tools could also lead to an oxidation reaction of phenolic compounds in cocoa beans. Furthermore, the cut scars on the cocoa beans are easily overgrown by fungi, which makes the process even more difficult. (Subroto et al., 2023)
d) Fermentation
Cocoa fermentation is the process of converting the sugar and citric acid present in the pulp into organic acids by microorganisms. This fermentation is essential as it gives the cocoa beans their distinctive aroma and taste after processing. During fermentation, the substrate which can be any substance that microorganisms convert – such as sugar and citric acid present in the pulp is metabolized into organic acids. These acids are then absorbed by the beans and trigger enzymatic reactions that contribute to the final taste, aroma and colour of the cocoa beans. (Apriyanto et al., 2016)
During the process of cocoa bean fermentation, naturally occurring microbes help break down the beans over 6 days. The microbes in the fermentation process produce compounds such as ethanol, acetic acid and lactic acid. As the acetic acid and alcohol diffuse into the cocoa bean, the temperature increases causing the seeds to die. The presence of Lactobacillus lactis and Acetobacter acetic can speed up the fermentation process. Yeast is dominant in the early stages of fermentation, followed by the growth of lactic acid bacteria and subsequently acetic acid bacteria. It’s important to avoid mould growth during fermentation, as it can produce mycotoxins and create a bitter taste in the cocoa. (Subroto et al., 2023)
e) Drying
After the fermentation process, the coffee beans are laid out to dry. The drying process can occur on trays, mats or concrete patios, depending on the size of the production and the local customs. Generally, the beans are spread out in a single layer to ensure uniform drying. Cocoa beans are considered suitable for marketing if their moisture content is reduced to between 5% and 8%.
Five drying systems used in the cocoa sector: open sun, solar, oven, microwave and freeze-drying. At the time of sale, the moisture content of cocoa from Africa and Asia is often high due to local drying methods, which typically involve open sun drying Dzelagha et al., 2020. Drying allows chemical changes during fermentation to continue, improving flavour and reducing bitterness, astringency and developing a chocolate brown colour in well-fermented cocoa beans (Afoakwa et al., 2014). The process of drying cocoa beans should only commence after the beans have undergone fermentation. Freshly harvested cocoa beans typically have a high moisture content of around 51-60%. This makes them more susceptible to damage or rot from the growth of microorganisms.
f) Storage
According to previous research, it is not recommended to store cocoa beans for an extended period to avoid damage. This is because dry products are hygroscopic and can easily absorb moisture until they reach equilibrium conditions. During the storage period, several strains of mold could be present, including Aspergillus penicillioides, Eurotium rubrum, Eurotium chevalieri, Eurotium amstelodami and Absida corymbifera. These moulds were a class of xerophilic fungi that could live in dry environmental conditions, aw and low moisture content conditions. (Kreibich et al., 2016)
4. Health benefits of Cocoa
5. Conclusion
After exploring the world of cacao and its processing techniques, it is clear that it offers an abundance of health benefits. By understanding how cacao is processed, individuals can make better decisions that not only satisfy their taste buds but also nourish their bodies and minds. The selection of beans and processing methods play a crucial role in determining the nutritional value and flavour of the final cacao product. Cacao has numerous benefits beyond its delicious taste, including high levels of antioxidants, mood-enhancing properties and potential cardiovascular advantages, which make it a vital component of a healthy lifestyle. By incorporating cacao into their diets in various forms, individuals can take advantage of these benefits and embark on a journey toward a healthier lifestyle.
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