Preliminary processing of cocoa beans is an important step in the processing of cocoa beans to create high-quality products that are suitable for the processing of finished chocolate products. However, in order to perform this stage well, it is necessary to pay attention to the requirements of the fermentation process and the biochemical changes.
Processing of cocoa beans:
Harvesting cocoa beans ---> Storing cocoa beans ---> Fermenting cocoa beans ---> Drying (drying) cocoa beans ---> Preserving cocoa beans
In the preliminary processing of cocoa beans, the fermentation stage is one of the most important because at this stage biochemical reactions in the beans occur intensely to create precursors for chocolate flavor. amino acids, reducing sugars, polyphenols...)[1]. Besides, it also creates raw materials for the processes of biochemical changes in quality in the stages of drying, drying, preserving, roasting and processing chocolate (acids, volatile substances, peptides, .. .) [first]. So what are the requirements during fermentation? What biochemical changes have occurred in it? What are the effects of these changes?
1. Some requirements in the fermentation of cocoa beans
Although each region, each country has specific fermentation processes to suit the main conditions in that place and create products typical of the region, of the region, but overall, there are still common requirements for the process. fermentation of cocoa beans to produce high quality products suitable for chocolate processing. Those requirements are:
The temperature during fermentation of cocoa beans needs to be between 45-50 degrees Celsius to destroy the vitality of the beans (avoid germination). This temperature is favorable for biochemical reactions in the granulosa cells to occur faster.
Fermentation time from 5-7 days for cocoa variety Forastero. Trinitario depends on the weather conditions of each region. If fermentation is too short, the biochemical process does not take place completely. If the fermentation process is too long, the decomposition of some organic substances in the grain occurs intensely and produces unpleasant odorous products such as: decomposition of proteins into NH3, oxidation of unsaturated fatty acids into aldehydes have an overpowering odor characteristic of cocoa and ester-forming reactions with undesirable odors...[2]
Appropriate level of aeration: normally anaerobic fermentation occurs for normal cocoa beans in 32-48 hours (cacao pods do not retain fruit). For cocoa beans with reduced water content (cacao pods are stored for about 9 days), after 24-32 hours. This is followed by aerobic fermentation (which requires air) to produce acetic acid. Thus, the required time of turning cocoa beans for normal cocoa beans (from non-storage cocoa beans) is once every 2 days and for cocoa beans from stored fruit for 9 days is once every 48 hours [3].
Type of cocoa bean incubation: the cocoa bean incubation box must ensure that there is no strange taste (smell of rubber, foam, pesticide, coal smell...). Not corroded by acids. The barrel material is not affected by acids and alcohol. The incubator must also be able to easily drain the viscous solution and keep the temperature.
Weight and height of cocoa bean mass: The mass of cocoa beans to achieve the best fermentation results is from 50kg of loose beans or more, the height of cocoa beans in fermentation at medium and small weight is not more than 40cm. With this mass and height, biochemical processes in the seeds will occur thoroughly and in a good trend [4].
2. Biochemical processes occurring in cocoa bean fermentation
The biochemical processes occurring in cocoa beans are mainly the fermentation of the cocoa bean mucilage (with a sugar substrate) and the biochemical reactions occurring in the endosperm of the cocoa bean. With a large sugar content of 10-12% dry matter (Wood and Lass., 1987) [5], this is a favorable environment for yeast fermentation to produce ethyl alcohol and grow. grow their biomass to produce CO2 and H2O.
However, the process of increasing the temperature of cocoa mass is determined by the aerobic activity of Acetobacter, Bacteria, etc. in the reaction from ethanol to acetic acid with energy up to 988 kJ/mol, with This energy has caused the mass of cocoa beans to increase the temperature from 45-50 degrees.
The fermentation process of the sticky rice layer has created a favorable environment in terms of pH, ethanol content, acid, temperature, air... for beneficial microorganisms (yeast, lactic acid bacteria, bacteria, etc.) acetic bacteria) in a certain period and is an unfavorable environment for other harmful microorganisms such as molds, rotten bacteria, etc. to develop. Thus, the fermentation process is favorable, harmful microorganisms will not grow.
Parallel to the external fermentation is a biochemical process that occurs inside the endosperm of the seed. Whether this process is intense or not depends on the content of acetic acid and lactic acid in the fermentation of the sticky rice layer. When these acids penetrate the endosperm, the cell rupture occurs. In the endosperm of cocoa beans, there are two main types of cells: cells containing polyphenol pigments (purple cells) and cells containing lipids and proteins (white cells). When these cell walls are broken down, the compounds inside are able to come into contact with each other. Under the action of enzymes, biochemical reactions have taken place. The products of these reactions are reducing sugars (simple sugars), amino acids, peptides, free fatty acids, polyphenols, sterols... These substances are the raw materials that create the characteristic flavor of chocolate through Mailar reactions, esterification reactions, oxidation reactions, caramelization... when roasting seeds at high temperatures (115 degrees C to 145 degrees C) [7].
Along with the process of acid transfer into the seeds, there is also a process of diffusion of substances inside the seeds out such as caffeine, theobromine to reduce the bitterness of the seeds and polyphenols to reduce the acrid taste of the seeds.
The acids move into the seed to initiate biochemical reactions that give the bean its chocolate color and flavor. Another aspect that needs to be considered is that after fermentation, a large amount of acid remains in the seeds and causes the sour taste of the product. These acids will be partly lost during drying (drying) by evaporation (mainly acetic acid), by displacement with moisture (mainly lactic acid). Thus, it is necessary to combine both fermentation and drying (drying) processes to obtain high quality seeds: both color and chocolate flavor and less bitterness, astringency and less acidity.
Cocoa flavor is determined by the precursors to create chocolate flavor (reducing sugars, amino acids, polyphenols...) so the more these precursors are, the better the cocoa flavor process and the higher quality cocoa beans.
Thus, the fermentation of cocoa beans is a necessary process to create high quality products suitable for chocolate processing. The biochemical changes in cocoa beans are so complex that scientists are also gradually understanding and explaining those processes. However, in order to perform well the fermentation process, we need to pay attention to some of the following requirements:
Harvest fruit at the right maturity, do not harvest green (father's fruit changes color), do not overripe fruit (germ on the tree), remove diseased fruits
Store the fruit for 7-9 days in a well-ventilated place to reduce the water content in the sticky rice layer
Fermentation in tanks can keep the temperature, have the right size, no strange taste and inert to chemical substances (acid, alcohol, etc.)
Fermentation time is from 5-6 days, the number of times of inversion is every 2 days
Good fermentation volume is from 50kg or more
The height of the cocoa bean mass in the incubation tank should not exceed 40cm.
Source: Mr. Phan Thanh Binh
Information:
Website: www.opetitmaison.com
Hotline: 0903453365
Address: Petit Coffee, 31 Nam Ho, Ward 11, Da Lat, Lam Dong
Comments