Comprehensive Rural Development Through Credit

Activities (Operations & Activities)

The Activities and operations of the Kerala State Co -operative Agricultural and Rural Development Bank includes the following:

Coffee Processing

Irrespective of the harvesting method, green coffee beans and overripe coffee cherries inevitably end up mixed with the perfectly ripe cherries and must be separated during coffee processing. Overripe coffee cherries, undeveloped coffee cherries, sticks and leaves float in water. Ripe coffee beans and green coffee cherries are dense and sink.
Therefore, the first step in coffee production consists of separating the "floaters" from the "sinkers." The coffee floaters are usually sent directly to the patio to be dried and are often slated for internal consumption. The ripe and green cherries can be sent to the patios to be dried using the natural process of preparing coffee or can be sent to the coffee pulping machines.

Coffee Processing Equipment

The first stage of coffee pulping is used to remove the green coffee cherries from the ripe cherries. In the coffee pulping machinery, the internal pressure is monitored to push the coffee against a screen with holes only large enough for a coffee bean (not cherry) to pass through. Since the ripe cherries are soft, they break and the coffee seed is released through the screen.

Pulping Coffee

The green cherries are hard and cannot be pulped. Instead of passing through the screen, the green coffee beans pass to the end of the barrel system and are separated from the ripe coffee beans. The pressure inside the barrel controls how many cherries will be pulped. A very high pressure will cause all of the cherries including the green beans to be pulped.
It is necessary to continuously monitor the pressure so that about 3% of ripe cherries are not pulped and are removed with the green cherries. This margin of error ensures that no green cherries are mistakenly pulped. The pulp and coffee beans are then separated by centrifugal force and a barrel screen system.

Molecular density sorting

The coffee beans covered in the slippery mucilage can be sent to the patios to dry as pulped natural coffees or can be sent to coffee fermentation tanks. The coffee fermentation tanks are used to remove the mucilage before drying.
The pulped coffee beans are put into cement tanks with water and are allowed to ferment for 16-36 hours. On the way to the fermentation tanks, another density separation can occur. The highest quality coffees are the densest and should be separated and fermented in a different tank.

Coffee Fermentation

The coffee fermentation time depends on a number of factors including the amount of coffee fermenting, water temperature, and humidity. The mucilage is made up of pectin materials including protopectin (33%), reducing sugars including glucose and fructose (30%), non-reducing sugars such as sucrose (20%), and cellulose and ash (17%. Protopectin is not water soluble and will hydrolyze to pectinic acid in the fermentation tanks (Wrigley, 455).
Hydrolysis of the protopectin and degradation of the pectin by enzymes is the process that occurs to remove the mucilage during fermentation (Wrigley, 455). Currently, the best way of determining the end of coffee fermentation is to feel the coffee beans to determine if they are still encased in mucilage. If the coffee beans are fermented for 36-72 hours, stinker beans develop. Lactic, acetic, and propionic acids are produced in this process and are believed to prevent the traditional fermentation taste by inhibiting mold growth that regularly occurs during drying on a patio in humid conditions (Wrigley).

Coffee Drying

From the coffee fermentation tanks, the beans are moved to drying patios and dried to 11-12% moisture content. A small portion of the lot is hulled and milled by a mini-huller. Three hundred grams of coffee is classified for defects (100 grams is often used), and the percentage of each screen size is determined.
Then, 200-300 grams of coffee is roasted in a sample roaster and cupped to determine coffee quality. Ideally no lots will be mixed until the coffee has been classified and cupped. The coffee remains in pergamino until shipment time to help protect the flavor and aroma of the coffee.

Coffee Bean Moisture Measurement

Before shipment, coffee is dried and a coffee moisture meter is used to measure coffee bean moisture. Coffee must be dried from approximately 60% moisture content to 11-12% moisture content. Coffee is typically dried on large patios made of asphalt or cement and then transferred to mechanical dryers. The coffee on the drying patios is shifted every 30-40 minutes and is shaped into long rows of no more than 5 cm in height.
Next to each row is open ground, which is warmed and dried by the sun. The coffee is then shifted onto the dry portion of the patio, and the section where it was previously is now allowed to dry in the sun. This helps accelerate the coffee drying process and prevents fermentation and moldy beans from developing. This method is widely used in Brazil, but less widely used in Guatemala or Costa Rica where the coffee is more often piled perpendicularly to the old piles.
Drying coffee solely by patio takes 6-7 days for washed coffees, 8-9 days for pulped naturals (semi-washed), and 12-14 days for natural (dry-processed) coffees. This is why coffee beans are typically dried on a patio until they reach a moisture content of 15% and are then transferred to mechanical dryers.
Once the coffee reaches a 25% moisture content or less, it can be piled at night and covered with cotton cloths to allow the coffee to breath. If it rains, these piles can also be covered with plastic. Coffee should not be covered with burlap sacks since this will impart a distinct burlap flavor and aroma to the coffee.

Coffee Drying Stages

In a study done in Kenya, Kamau reports that there are six stages to drying coffee.

  • Skin drying. Moisture 55-45%
  • White Stage drying. Moisture 44-33%
  • Soft Black stage. Moisture 32-22%
  • Medium Black Stage. Moisture 21-16%
  • Hard Black Stage. Moisture 15-12%
  • Fully dry coffee and conditioning. 11-10%

In this study he found that sun drying coffee for stage three is mandatory for coffee quality. He also reports that as long as the temperature was between 40-50°C--which means a bean temp of 35°C--then the coffee quality will not be seriously compromised during the other coffee drying stages.
The final two coffee drying stages (15-11% moisture) take just six hours at 40°C in a mechanical dryer.

Coffee Drying Equipment

There are several coffee dryer systems available. Many older dryers are converted grain dryers that are not as efficient as the new horizontal barrel dryers. The new coffee dryers are designed to mix the coffee evenly to ensure uniform drying. Drying coffee by using mechanical dryers accelerates the slowest part of the coffee drying process (15-11%) and helps prevent fermentation.
In some environments that have a high humidity the entire drying process must take place in mechanical dryers. Mechanical dryers should never be set higher than 40-45°C and this question should be asked before buying any coffees that have been mechanically dried. At higher temperatures the germ is killed and the flavor potential of the coffee is ruined. At extreme temperatures the bean crystallizes, and when smashed with a hammer, will break like glass.

Other Machinery for Drying Coffee

The best, but least utilized method of drying coffee is by using drying tables. In this method the pulped and fermented coffee is spread thinly on raised beds, which allows the air to pass on all sides of the coffee. The coffee is mixed by hand and the drying that takes place is more uniform and fermentation is less likely. Most coffee from Africa is dried in this manner and select coffee farms around the world are following their lead.
A relatively new method of drying coffee is solar drying. Solar coffeee dryers are more economically sound than mechanical coffee dryers because they don't rely on fossil fuels or electricity. They are also more efficient than the patio drying technique because their hotter drying temperatures dry coffee beans at a faster rate. While solar coffee dryers have great potential for saving energy, they are not widely used today.

Coffee harvesting season

In India, there is only one cropping season. Arabica coffee is harvested from November to January and Robusta from December to February. Coffee is harvested during the dry season when the coffee cherries are bright red, glossy, and firm.
Coffee is processed either by wet method to produce plantation/parchment coffee or by dry method to obtain cherry coffee and both these processing methods involve skill as well as science. For preparation of both these types, picking of fruits at the correct stage of ripening (just ripe berries - on gentle squeezing the fruit, the beans inside pop up easily) is essential.
Over or under-ripe berries result in poor cup quality after processing. If, for any reason, coffee cannot be harvested as and when it ripens, the over and under-ripe fruits and also green fruits should be sorted out and processed separately as cherry. Just ripened berries are ideal for pulping to prepare washed/parchment coffee

How to Harvest Coffee Beans

Ripe cherries are either harvested by hand, stripped from the tree with both unripe and overripe beans, or all the coffee beans are collected using a harvesting machine. These processes are called selective picking, stripping, and mechanical harvesting, respectively. To maximize the amount of ripe coffee harvested, it is necessary to selectively pick the ripe coffee beans from the tree by hand and leave behind unripe, green beans to be harvested at a later time.
Manual harvesting is practiced in India. It is the most labour-intensive operation.

Storing Green Coffee Beans

Coffee must be stored in dry and cool conditions. Exposure to the sun or moisture will rapidly deteriorate the coffee. Storage in pergamino until right before the shipping time will help preserve the coffee. Burlap bas are often used for coffee bean storage because they allow air flow. They also preserve the coffee longer than plastic or paper bags. Burlap bags should be aired on the patios before storing coffee to prevent a baggy flavor or burlap scent from being imparted to the coffee.

Coffee Seedlings Storage

Research in Kenya has shown that coffee seeds are useful for over two years if stored at 15°C at 41% moisture content in an airtight polythene bag

Roasted Coffee Storage

Whole bean coffee maintains its freshness the longest. The freshness of ground coffee will be lost in a matter of minutes since its protective cellular structure has been broken and the volatiles have been exposed to the environment to undergo oxidation. An inert gas such as nitrogen can be used to help preserve the whole beans for an extended time.
Some people claim that nitrogen could preserve coffee for up to two years, but after a few weeks the coffee no longer acts, tastes, nor smells like freshly roasted coffee. Whole bean coffee that has been opened and exposed to the environment should be kept for no longer than a week even if a vacuum seal is in place. Coffee that has been roasted very darkly is even more susceptible to oxidation and should be kept for an even shorter period of time.
Finally, there is a significant loss in crema development for espresso coffee four days after roasting. Espresso coffee should be purchased immediately after roasting and consumed within a couple of days.

Economic Importance

The importance of coffee in the world economy cannot be overstated. It is one of the most valuable primary products in world trade, in many years second in value only to oil as a source of foreign exchange to developing countries. Its cultivation, processing, trading, transportation and marketing provide employment for millions of people worldwide.
Coffee is crucial to the economies and politics of many developing countries; for many of the world's Least Developed Countries, exports of coffee account for a substantial part of their foreign exchange earnings in some cases over 80. Coffee is a traded commodity on major futures and commodity exchanges, most importantly in London and New York.

Nutritional Significance

Depending on the type of coffee and method of preparation, the caffeine content of a single serving can vary greatly. On average, a single cup of coffee (about 200 milliliters) or a single shot of espresso (about 30 mL) can be expected to contain the following amounts of caffeine.

Content Amount
Drip coffee 115–175 mg (560–850 mg/L)
Espresso 60 mg (2000 mg/L)
Brewed/Pressed 80–135 mg (390–650 mg/L)
Instant 65–100 mg (310–480 mg/L)
Decaf, brewed 3–4 mg
Decaf, instant 2–3 mg

Medicinal Properties

Caffeine is the major coffee constituent which the coffee tolerance or intolerance depends on. In a healthy liver, the majority of caffeine is degraded by the hepatic microsomal enzymatic system. Caffeine is mostly degraded to paraxanthine substances, partially to theobromine and theophylline, and a small amount of unchanged caffeine is excreted by urine. Therefore, the metabolism of caffeine depends on the state of this enzymatic system of the liver.
Elderly individuals with a depleted enzymatic system do not tolerate coffee with caffeine. They are recommended to take decaffeinated coffee, and this only if their stomach is healthy, because both decaffeinated coffee and coffee with caffeine cause heartburn. Moderate amounts of coffee (50-100 mg of caffeine or 5-10 g of coffee powder a day) are well tolerated by a majority of elderly people, who enjoy to meet and chat over a cup of coffee. Excessive amounts of coffee, however, can in many individuals cause very unpleasant, exceptionally even life-threatening side effects.
Coffee consumption can lead to iron deficiency anemia in mothers and infants. Coffee also interferes with the absorption of supplemental iron. American scientist Yaser Dorri has suggested that the smell of coffee can restore appetite and refresh olfactory receptors. He suggests that people can regain their appetite after cooking by smelling coffee beans, and that this method can also be used for research animals. Many high end perfume shops now offer coffee beans to refresh the receptors between perfume tests.