Chocolates are the wonder product comes out from cocoa. Cocoa fruits are yellow pods with a violet colour kernel. Many varieties are found in different countries such as Criollo, Trinitaro etc. Size, kernel colour, sensitivity to disease may vary depending on the variety.
After collecting the harvest, the fruits are left for few days for the attached seeds to detach from the husk. Shell and silver skin is removed when making chocolates with cocoa. Mucilage consists of nutrients, which are degraded by microbes during fermentation which results in change in flavour and aroma.
Cocoa seeds do not germinate during fermentation as microbial activity releases heat and the internal temperature rises. Inhibiting germination is one purpose of leaving the seeds for fermentation. Mucilage acts as a barrier to moisture removal. After fermentation, it can be easily removed and dried. Many biochemical reactions occur during fermentation.
The scientists have investigated cocoa fermentation and realized that the microflora were responsible for the maceration of pulp of the mucilage and killing the seeds. The seeds in a pod are sterile. When the seeds are extracted from the pods after harvesting by manual operations, they get exposed into the atmosphere where the microbes come in contact with the seeds. Fungi, Yeast and bacteria are generally involved in this fermentation process. Fungi like Aspergillus, Mucor, Penicillium, Rhizopus ; Yeasts like Saccharomyces, Pachia, Kloeckera, Candida and bacteria like lactic acid bacteria, acetic acid bacteria participate in fermentation. In first few hours of fermentation, yeast multiplication takes place. The pH of the mucilage will be around 3.6. In later stages, the environment inside the pod becomes anaerobic. Yeasts utilize the sugars in mucilage and produce Carbon dioxide. Initial temperature which was about 25 0 C rises to about 32-36 0C. Yeasts consume citric acid available in the mucilage and results in pH increase up to 4. Yeasts release pecteolytic enzymes which hydrolyzes the pectin.
In these conditions; pH 4 and temperature 320 C and anaerobic; lactic acid bacteria starts to grow. As the amount of sugars left is low, this occurs at a short period of time. These bacteria produce lactic acid. Acetic acid bacteria develop when alcohol is released into the medium as an end product by other microbes. Acetic acid bacteria convert lactic acid to acetic acid to convert energy. Small amount of acetic acid will be evaporated and the remaining penetrates into the kernel. This increases the cell wall permeability and results in further increase in pH and consequently allows biochemical reactions introducing precursors of aroma and flavour compounds. At increased pH levels, many bacteria tend to grow. In the final stages, the matrix will be rich with bacteria which break down and produce amide and some ammonical compounds. By this time, mucilage is degraded.
In the cotyledon, protein breakdown, formation of complex compounds with polyphenols, sugar hydrolysis, diffusion of organic acids and increase in permeability results. Sugar breakdown products are essential precursors of chocolate aroma. Some compounds like aldehydes, pyrazines produced are directly involved in aroma development. Caffeine and theobromine which are alkaloids diffuse from kernel cells into the outside matrix decreasing the bitterness. Polyphenolic compounds and alkaloids in pigmented cells are increased by 8-18% during fermentation. These involve flavonols, anthocyanidines, hydrocinamic derivatives and coumarin. Organic acids produced include Citric acid, Acetic acid, Lactic acid, Oxalic acid and Mallic acid. After fermentation drying rate can be increased and eventually washing away the mucilage of fermented cocoa beans.
After fermentation, beans with mucilage and placenta have to be separated from the husk pieces after the mechanical breakage. This operation is often more difficult than opening the pods. Cleaned fermented cocoa beans are roasted at 160 0C for three hours which allows enhancement of aroma and flavour followed by conching. During conching, the bitterness further reduces and also reduces the level of acetic acid. Roasting step is not sufficient to remove acetic acid.
When making chocolates, as the chocolate powder particles are very fine, the surface area is enormously large and the added fat is covered around the particle. The fat layer around the fine particles adsorb flavour and aroma compounds. Therefore, flavour characteristics are improved in the final product.
After collecting the harvest, the fruits are left for few days for the attached seeds to detach from the husk. Shell and silver skin is removed when making chocolates with cocoa. Mucilage consists of nutrients, which are degraded by microbes during fermentation which results in change in flavour and aroma.
Cocoa seeds do not germinate during fermentation as microbial activity releases heat and the internal temperature rises. Inhibiting germination is one purpose of leaving the seeds for fermentation. Mucilage acts as a barrier to moisture removal. After fermentation, it can be easily removed and dried. Many biochemical reactions occur during fermentation.
The scientists have investigated cocoa fermentation and realized that the microflora were responsible for the maceration of pulp of the mucilage and killing the seeds. The seeds in a pod are sterile. When the seeds are extracted from the pods after harvesting by manual operations, they get exposed into the atmosphere where the microbes come in contact with the seeds. Fungi, Yeast and bacteria are generally involved in this fermentation process. Fungi like Aspergillus, Mucor, Penicillium, Rhizopus ; Yeasts like Saccharomyces, Pachia, Kloeckera, Candida and bacteria like lactic acid bacteria, acetic acid bacteria participate in fermentation. In first few hours of fermentation, yeast multiplication takes place. The pH of the mucilage will be around 3.6. In later stages, the environment inside the pod becomes anaerobic. Yeasts utilize the sugars in mucilage and produce Carbon dioxide. Initial temperature which was about 25 0 C rises to about 32-36 0C. Yeasts consume citric acid available in the mucilage and results in pH increase up to 4. Yeasts release pecteolytic enzymes which hydrolyzes the pectin.
In these conditions; pH 4 and temperature 320 C and anaerobic; lactic acid bacteria starts to grow. As the amount of sugars left is low, this occurs at a short period of time. These bacteria produce lactic acid. Acetic acid bacteria develop when alcohol is released into the medium as an end product by other microbes. Acetic acid bacteria convert lactic acid to acetic acid to convert energy. Small amount of acetic acid will be evaporated and the remaining penetrates into the kernel. This increases the cell wall permeability and results in further increase in pH and consequently allows biochemical reactions introducing precursors of aroma and flavour compounds. At increased pH levels, many bacteria tend to grow. In the final stages, the matrix will be rich with bacteria which break down and produce amide and some ammonical compounds. By this time, mucilage is degraded.
In the cotyledon, protein breakdown, formation of complex compounds with polyphenols, sugar hydrolysis, diffusion of organic acids and increase in permeability results. Sugar breakdown products are essential precursors of chocolate aroma. Some compounds like aldehydes, pyrazines produced are directly involved in aroma development. Caffeine and theobromine which are alkaloids diffuse from kernel cells into the outside matrix decreasing the bitterness. Polyphenolic compounds and alkaloids in pigmented cells are increased by 8-18% during fermentation. These involve flavonols, anthocyanidines, hydrocinamic derivatives and coumarin. Organic acids produced include Citric acid, Acetic acid, Lactic acid, Oxalic acid and Mallic acid. After fermentation drying rate can be increased and eventually washing away the mucilage of fermented cocoa beans.
After fermentation, beans with mucilage and placenta have to be separated from the husk pieces after the mechanical breakage. This operation is often more difficult than opening the pods. Cleaned fermented cocoa beans are roasted at 160 0C for three hours which allows enhancement of aroma and flavour followed by conching. During conching, the bitterness further reduces and also reduces the level of acetic acid. Roasting step is not sufficient to remove acetic acid.
When making chocolates, as the chocolate powder particles are very fine, the surface area is enormously large and the added fat is covered around the particle. The fat layer around the fine particles adsorb flavour and aroma compounds. Therefore, flavour characteristics are improved in the final product.
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