Fermented Cocoa, Tea, and Coffee products Flashcards
(47 cards)
How coffee beans look like
Coffee is grown as coffee cherries , bean are covered in the silverskin that are inside the pulp
By what plant genus coffee beans are produced? how many species of coffee are commercially produced and where
Coffee beans are produced by the genus Coffea
More than 40 species are known, but only a few are commonly available on the market including: C. arabica, C. robusta
- *C. arabica** originated from Brazil, and are currently cultivated in South America, Central America, and some African countries
- *C. robusta** is grown in Cote de Ivorie, Cameroon, Uganda, Indonesia, and India
•It takes approximately ___ from flowering for the coffee cherries to reach maturity
1-year
Why fermentation is used in coffee?
•It is necessary to first remove the parchment and the pulp layer to obtain the green coffee beans, which can then be dried, roasted, milled, and used for making coffee
That is why fermentation is used, it is made to remove the pulp to obtain the green coffee beans
•The fermentation of coffee causes the degradation or breakdown of the mucilage around the parchment skin, which gives the bean a better appearance
What is the harvesting and processing for coffee? Three types of drying processes
What is the principle of wet processing fermentation
- •After harvesting the mature beans are mechanically de-pulped
- •This is followed by a fermentation step to convert the remaining mucilage into water-soluble products that are removed by washing prior to the final drying
- •The de-pulped berries are held under water in wood or concrete bins
- •Once the sticky pulp layer is converted into water-soluble products the beans are washed with water and then sun dried or washed with a mechanical drier
Over fermentation in wet coffee processes will cause what
•Over-fermentation will cause spoilage and the development of off-flavours
What types of enzymes bacteria used in wet processing fermentation should have
Pectinases:
•The mucilage is mostly composed of pectin, therefore the microorganisms that are involved in this reaction must have pectinases
What types of microorganisms perform wet processing fermentation: in general and then specific types+ specific types for pectinolytic species and the ones that have been isolated from Kona Coffee beans
- Coffee beans undergo a fermentation step to prepare the fruit for commercial use
- This fermentation involves molds, yeasts, several LAB species, and a few Gram-negative bacteria that originate from the surface of the fruit and soil
- Most of the microorganisms detected during these fermentation steps belong to Enterobacter and Escherichia
- Pectinolytic species then colonize and dominate the fermentation including Bacillus, Fusarium, Penicillium, Aspergillus
- Erwinia dissolvens have been specifically isolated from Kona Coffee beans
How wet-process fermentation is carried out? How long? What is the end result?
- The fermentation reactions is conducted in concrete tanks or bins 1 to 10 m deep, with the bottom of the tank able to allow the water to drain
- The fermentation can last from 24-90h based on climatic conditions
- The end of the fermentation is based on when the mucilaginous tissues change from viscous to liquid
How the dry processing for coffee fermentation is carried out?
What factors effect the rate of demucilagination? What does it depend on? What type of coffee takes longer to complete it
•The rate at which demucilagination occurs can depend on altitude and temperature
and due to its thicker mucilage, robusta coffee takes longer for complete demucilagination
Are starter cultures used for coffee?
•Although starter cultures have the potential to speed this process and improve coffee quality, little research has been conducted on using or making commercial starters
what is civet coffee?
What is the roasting stage in coffee making? What are the conditions?
- Industrial roasting ranges from 90 s to 6 min, while handcrafted roasting may range between 18-20 minutes
- Roasting conducted using rotary drums at temperatures from 200-250C
- Coffee produced in each country by various processes have its own unique flavor
What is the raw material for chocolate? any other related products?
•Cocoa beans are the raw material for the production of several products including cocoa powder, cocoa butter, and chocolate
Histrorically how fermentation of cocoa beans was used
•In historical times its thought that fermentation was conducted simply to remove the mucilaginous pulp surrounding the cocoa seed and facilitate drying
Why fermentation is done today for cocoa beans
- The main reason for this fermentation is to induce biochemical transformations within the beans that lead to the color, aroma, and flavor precursors of chocolate
- Cocoa pods are opened after harvest
- Cocoa pods contain cocoa beans surrounded by a white, carbohydrate rich mucilaginous pulp
- This pulp is the substrate for the fermentation
What is the initial microorganism that starts cocoa fermentation? Conditions favoring its growth? What is happening? (pH of CHO pulp, mention end products at this stage), what enzymes these microorganisms have
- The carbohydrate rich pulp has a pH of 3.0-4.0 and is anaerobic because the pulp/bean mass is stored in heaps or boxes
- This favors the growth of yeast (which originates from the flowers or fruit of the cocoa plants)
- The yeasts initiate an anaerobic alcoholic fermentation and convert carbohydrates (sucrose and glucose) into ethanol and CO2
- Pectinolytic enzymes are also produced by the yeast and they degrade pectin allowing the air to progress into the mass during fermentation since the pulp becomes less viscous and begins to drain
What is the next microorgnanism after yeast? what do they do? why particular them
•The presence of air and ethanol then favors LAB, which can ferment carbohydrates (glucose and fructose) via the homofermentative pathway into lactic acid, or the heterofermentative pathway into lactic aid, acetic acid, ethanol, and CO2
What bacteria comes after LAB in the final stage? What do they contribute
- In the final stages of cocoa bean fermentation the conditions become favorable to AAB due to the aeration caused by further breakdown of the pulp and the availability of ethanol and organic acids
- The AAB oxidize the ethanol into acetic acid
- The acetic acid diffuses into the cocoa bean and is responsible for the death of the embryo, and this marks the end of the fermentation
What happens with sugars during cocoa bean fermentation?
- Glucose at the beginning of the reaction is used by yeast which is the best competitor for this nutrient
- Glucose not used by yeast remains to be fermented by LAB into lactic acid, acetic acid, carbon dioxide, and ethanol
- Fructose is fermented by LAB
- Heterofermentative LAB use fructose as a terminal electron acceptor
- When the fructose is reduced it generates mannitol as a biproduct
By-product of fructose as a terminal electron acceptor by heterofermentative bacteria
Mannitol
How the fermentation process is arranged for cocoa?
- Box fermentation is the most common method.
- There is a cascade of three boxes. The fermented cocoa beans are transferred every 24 hours to a lower box.
- At the end of the process the fermented cocoa beans are collected