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Coffee

Coffee


Family: Rubiaceae
Genus: Coffea
Species: arabica

Of all coffee species, Coffea arabica is considered to make the superior beverage. It accounts for more than three-quarters of the world production in spite of being prone to a devastating rust disease. C. arabica is indigenous primarily to the area around Kaffa in Ethiopia. For many years this area was "closed", and the genetic breeding pool was limited to one seedling taken to Amsterdam in 1706 from a planting in the East Indies. The resultant inbreeding still may be a significant factor in what cultivars are presently available.

The first "coffee" drink was made from fermented fruit pulp. Not until the 15th century were dried "coffee" beans roasted, ground and a beverage extracted. In 1650 coffee from Arabia reached England, and by 1675 there were more than 3,000 forerunners of StarbucksTM.

C. arabica thrives and produces the most prized beans in the moderate (maximum of about 70o F) climates encountered at higher, frost-free elevations. Excellent coffee is produced near the equator up to 6000 feet. Growing conditions at this elevation correspond approximately to the coastal conditions at 34 degrees latitude (Santa Barbara and Ventura Counties). A good tasting coffee has been made from beans grown in Santa Barbara backyards.

Challenges facing production in California include adapting cultural techniques to California conditions, marketing California specialty coffees, and minimizing labor costs attendant with picking and grading without significantly degrading product quality.

Botany

Coffee belongs to the Ixora tribe of the very large Rubiaceae family. It is more distantly related to gardenias and quinine. The family is concentrated in the tropics and subtropics.

The genus Coffea has over 60 species of which about ten are utilized for coffee. Chief among these is C. canephora (aka Robusta) which is grown in disease prone areas and, to lesser extents, the more inferior C. lierica and C. dewevrei (Excelsa). C. Arabica is tetraploid (2n=44). Self-sterile diploid mutants are common and fertile hybrids have been made with Robusta, which is diploid.

C. arabica can be expected to grow to about 14 feet in our climate with a shallow tap root of about 4 feet. Leaves are opposite, shiny dark green, and lanceolate (4 to 6 inches by 2 to 3 inches) with acuminate tips. Coffee flowers that resemble quarter inch gardenia blossoms are borne in pairs at each leaf along the horizontal branches. Tetraploid cultivar flowers are normally self-fertile except if borne during very hot weather. Then star flowers are produced which have small, fleshy, greenish petals and no functional stamens. In the tropics flowering is initiated during the rainy season following a dry period. Put another way, flower buds remain dormant during dry periods. Coffee fruit are called berries or cherries. They are about 3/4 inch in diameter and ripen in 6 to 7 months to red then turn reddish purple. (The variety 'Bourbon' ripens to yellow.) Inside the skin is the mesocarp (fruit flesh or pulp) which is about one tenth of an inch thick. The fruit usually contains two seeds and occasionally three. One-seeded exceptions are termed peaberries and usually bring a premium price due to the perception that they are more flavorful. Trees start to produce sufficient quantities to make picking worthwhile in four or five years.

Cultivars

Two strains of Coffea arabica appeared relatively early in the 1700's, the original taken by the Dutch to Amsterdam termed typica (sometimes termed 'Nyasa') and a mutant, bourbon, propagated by the French in Bourbon (now Reunion). These two strains are the progenitors of all the current varieties. No attempt is made here to separate varieties and mutants from cultivars as is done in some references.

Important Varieties

Cultivars
'Arabica' or 'Typica': Still constitutes the bulk of the world's coffee; vigorous tree that needs to be topped. 'Kent's': Originated in Mysore, India and also grown in East Africa; vigorous and high yields of quality coffee; very susceptible to coffee berry disease; some resistance to Hemileia; being replaced by more resistant 'S.288', 'S.333' and 'S.795'.
'Baron Goto Red': May be the same as or is very similar to 'Catuai Red'. Grown at several sites in Hawaii. 'Laurina': Drought resistant, good quality, but only fair yields.
'Blue Mountain': Originated from the variety arabica in Jamaica and also grown in Kenya. It is resistant to coffee berry disease, the fungus Colletotrichum coffeanum. 'Maragogipe': Extremely vigorous, noted for its very large beans, but only fair yields; grown in Brazil and Central America.
'Bourbon': Was heavily planted in Brazil because of higher yields, but has been replaced there by 'Mundo Novo'; tree is more slender than var. arabica. 'Mundo Novo': Originated in Brazil as a cross between varieties 'Arabica' and 'Bourbon' which it closely resembles; very vigorous, excellent yields, favored in Brazilian plantings.
'Catimor': Newer selection; excellent producer, average quality. 'Pacas': Originated in El Salvador; good producer and popular in Latin America.
'Caturra': Prominent variant of var. bourbon but smaller; early bearer, very productive, grown widely in Colombia. In Hawaii, Yellow and Red variants are identified. 'Preanger': Being evaluated in Hawaii.
'Columbiana': Originated in Columbia; vigorous, heavy producer, average quality. 'Pretoria': Being evaluated in Hawaii.
'Columnaris': Tall tree that is an excellent producer, grown in Puerto Rico under shade. 'Purpurescens: Form characterized by purple leaves
'French Mission': Originated from seed imported in Kenya in 1893; also extensively planted in Tanzania. 'Semperflorens': Noted for continual flowering and production.
'Guadalupe': Being evaluated in Hawaii. 'San Ramon': Originated from the variety arabica; very small tree, productive, drought resistant, wind tolerant.
'Guatemala(n)': Being evaluated in other parts of Hawaii. See 'Kona'. 'Villalobos': Originated from 'San Ramon'; planted in Costa Rica.
'Kona': Main Hawaiian variety introduced into Kona 100 years ago as 'Guatemalan' (var. typica);. variations include 'Kainaliu', 'Kealakekua', 'Kuki', 'Eleele', 'Honomalu', 'Maki', 'Kekaha Lanai', Lahaina', and 'Waikapu'. 'K7', 'SL6', 'SL26', 'H66", 'KP532': Promising new cultivars that are more resistant to the different races of Hemileia.

 

Climatic requirements

All of the coffee species require a tropical or semitropical climate and produce best when they receive 70 or more inches of rain annually. Elevations of 3,500 to 6,000 feet produce the premium coffees. Notable exceptions do exist, such as the Hawaiian Kona coast and Molokai that have moderate climate conditions nearer sea level.

C. arabica requires a relatively frost-free environment similar to papaya. Mature trees can be expected to withstand short periods of 30° F, although new shoots may not be produced readily afterwards.

Coffee likes moist conditions and does not tolerate hot, dry winds. For these reasons much of the world's coffee is grown under shade trees which also protect against the overhead tropical sun. The coffee produced under such conditions brings a premium price.

Soil Requirements

Coffee will succeed on many types of soil but will develop a better root system in deep well-drained soils. A pH of 4.2 to 6 is preferred. Above 7 chlorosis can be expected.

Cultural Requirements

Spacing

Trees are normally planted on 3 to 8 foot centers. Tighter centers are used where intensive pruning is employed.

Fertilization and watering

Watering needs to be consistent, comparable to avocado. A dry period is needed to induce blossoming. Gibberillic acid sprays have been successfully used to break dormancy. Coffee responds to nitrogen, potassium, and minor elements in tropical settings. No studies of nutritional needs under California conditions have been made; therefore, a leaf analysis may be prudent.

Pruning

The main reasons for pruning are to prevent alternate bearing since blossoms are borne on new wood. In addition a key labor cost consideration is to hold the tree to a size that can readily be picked. In the 1950's in Hawaii, 15,000 pounds of cherries per acre was typical. In the intervening 50 years labor costs have necessitated a change in pruning practices. Now the yield is 4000 pounds per acre.

Pests and Diseases

The list of coffee diseases reported in coffee growing areas is long, some 30 diseases in one summary report, none of which appear to be significant in California at this time. Because of its Mediterranean climate few diseases are expected in coastal California. Three diseases are significant enough to deserve mention. 'Arabica' is prone to the devastating Hemileia vastatrix rust which destroyed coffee industries in Ceylon and India in the 1800's and, at times, has played havoc in most of the coffee growing districts in the world. The disease appears to be most devastating at lower elevations. No good control is presently known. Growers in infected areas have switched to other crops such as tea or to resistant robusta or less susceptible cultivars of C. arabica. The Coffee Berry Disease (CBD), Colletotrichum coffeanum, is major though not fatal. It is a widespread problem that is controlled with fungicides. Another major problem has been Fusarium strangulation encountered after trees suffer frost damage.

Birds, rats, rabbits and squirrels are some of the vertebrates that are attracted to coffee berries.

In coffee growing areas insects are a major problem. The most important is a borer that attacks the fruit, Stephanoderes hampei, which has spread from Africa to nearly all the coffee producing areas in the world.

Insect problems in California are expected to be limited. Fuller rose beetle (Pantomorus cervinus) has been noted as a coffee pest. Green coffee scale (Coccus virdis) is the most serous insect pest in Hawaii and can be easily controlled. Limiting the ant population appears to be essential for good control.

Propagation

Seed has good viability if stored properly and is considered an economical way to obtain trees that are sufficiently if not completely 'true' to the parent(s). Although seedlings have a good probability of producing good coffee, trees are grafted on seedling rootstock to ensure reliable results. Grafting is done in the spring at or before leaf drop. Clonal reproduction is also done with cuttings. Cuttings are collected from main or upright growing branches to avoid vine-like growth characteristics. They need to be kept moist until they are placed in the rooting medium. During rooting, they should be maintained at high (90%) humidity. Rooting will take about 75 days. Tissue culture is also employed to produce clonal stock. Recently, genetic engineering efforts have been initiated to introduce resistance disease and herbicides.

Nutrition

Roasted coffee beans have the following nutritional content per 1 gram of beans. (Note that analyses vary depending on the type, roasting, etc. and the values here are only a relative guide whose accuracy is approximately +/- 20%.)
calories 2.3 calories iron 0.029 milligrams
carbohydrates 0.63 grams thiamin 0.706 milligrams
fats 0.18 grams riboflavin 0.508 milligrams
proteins 0.13 grams niacin 0.170 milligrams
fiber 0.076 grams ascorbic acid   no data
calcium 1.5 milligrams beta-caritene   no data
phosphorus 2.0 milligrams caffeine 11-14 milligrams

 

Caffeine content of coffee is a major concern for many consumers. Decaffeination is about 98% effective in its removal. The table lists the caffeine content of 12 ounce cups of some common beverages.
Drip coffee
170-275
milligrams
Percolator coffee
120-200
milligrams
Instant coffee
90-150
milligrams
Espresso
600-900
milligrams
Tea
45-100
milligrams
Hot chocolate
15-30
milligrams
Cola
37-45
milligrams
JoltTM
71
milligrams

Harvesting and Processing

The highest quality coffee is obtained by hand picking the ripe berries at intervals of several weeks. In some areas berries are gathered from the ground, but the resultant beans are usually are of low quality. In Java the beans that have passed through the digestive tracks of birds bring a premium price. After collecting the berries, they usually are sorted to eliminate poor berries and sized to improve processing uniformity.

After picking, the berries must be processed quickly to prevent spoilage. Two methods are employed, 'dry' and 'wet'. In the dry approach berries are sun-dried and then hulled in cylinders to free the seeds. The remaining thin parchment over the bean is then removed by a sieving action that requires uniform bean size to be effective. In the wet method the berries are washed, pulped, and macerated in water. Fermentation then ensues, and in a little over 35 minutes the beans are freed. Sometimes a caustic solution is added to expedite the process. After a final wash the beans are placed in dryers which eliminate the parchment, or it is removed mechanically. The beans can now be stored for brief periods or aged under carefully controlled conditions to enhance flavor. Before shipping, beans are normally graded. Unfortunately, many grading systems exist and the criteria vary greatly.

The final step, roasting, develops the flavor desired by the customer. It is easy to ruin what began as a high quality product. Further, consistency is important from a market standpoint.

Fiscal

The major cost factor is the hand labor attendant with picking and sorting. In one day a picker can select and pick berries equivalent to 25-35 pounds of green beans. One tree produces about 5 pounds of green beans which reduces to one pound of roasted product.

The cost of labor associated with picking and sorting can put the price of the final product beyond what the customer is willing to pay. Reducing the diligence during pickings or berry selection results in the inclusion of over and under ripe berries that reduce the quality of the final product and will impact the selling price. Mechanical picking and mechanized sorting can be employed to reduce labor costs, but the capital investment would be difficult to recapture even for large operations. Another approach is to apply gibberellin to concentrate the blossoming period. Further, spraying immature cherries with ethephon, a chemical that produces ethylene, induces more uniform ripening. The attendant fiscal tradeoffs are not easy to establish at this time since the California growing factors and market are not well known.

The fiscal aspects of orchard investment are similar to that for lemons.

Market

The market for a California specialty coffee is undetermined. However, a similar marketing situation would appear to be that of the tea produced on the barrier islands near Charleston, South Carolina. Although labor and growing conditions are not the equal of those in China, Sri Lanka or India, the "only tea grown in America" fetches a premium price in specialty outlets such as those catering to tourists.

Compiled by Robert Vieth, Master Gardener