The pineapple is the most famous and economically important member of the Pineapple family (Bromeliaceae). It is the only bromeliad with edible fruit. The family is almost exclusively from the New World, with over 2000 species besides the pineapple native to the tropical Americas. One additional species is from Africa. The pineapple, however, can now be found in all tropical regions. Portuguese explorers carried it around the world in the 16th century. The Chinese were cultivating it by 1640, but it was only introduced to Hawaii in 1813. Hawaii started exporting canned pineapples in 1892 and James Dole started his plantation there in 1900.
In contrast to most of its Bromeliad relatives, the pineapple is terrestrial. It grows best in a mineral soil medium. Bromeliads typically are epiphytic (growing upon other plants) and do not require a mineral soil but do best living on bark or humus in the crotches of tree branches.
While most everyone is familiar with the pineapple fruit, many do not know what kind of plant produces it. Pineapple plants are perennials growing from a thick crown close to the soil surface. They reach a height of 4 feet with numerous stiff 3-foot long leaves often armed with sharp edges.
The pineapple “fruit” is not really a fruit at all but is a mass of individual berries fused to the central stalk. This is why the “fruit” has leaves on top. They are actually the continued growth of the stalk beyond where the berries are attached.
Pineapples are not grown from seed. The important commercial cultivars such as ‘Smooth Cayenne’ from Hawaii and ‘Red Spanish’ from the West Indies are self-sterile – the inconspicuous flowers are not capable of fertilizing their own eggs. Unless different cultivars are grown near each other (an unlikely occurrence in commercial plantations), the resulting fruits are seedless (parthenocarpic). Pineapples are readily reproduced by vegetative propagation, using crowns, slips, or suckers. The crown is the vegetative shoot on top of the fruit, and new plants take 2 years to produce fruit. Slips are side shoots from just below the fruit. Plants from slips take 20 months to produce fruit. Suckers are side shoots that develop from the main stem at ground level, and take 17 months to produce fruit.
Each plant that is propagated produces one fruit at the top of its stem. This high quality fruit is called the “plant” crop. After the fruit is harvested, several suckers develop and one year later produce the “ratoon” crop. The fruits are smaller and of lesser quality. A second ratoon crop can develop after the first crop is harvested. After that, the field is dug up and replanted.
Pineapple fruit quality is at its best only if the fruit matures on the plant. They do not become sweeter if harvested earlier since there are no starch reserves to be converted to sugar. The sugar content must come from the rest of the plant.
Pineapples are 15% sugar along with malic and citric acids. In areas near where it is grown, a pineapple wine is fermented. It does not store well so it is rarely seen outside of the tropics. Pineapples also contain bromelain, a protein digesting and milk-clotting enzyme similar to pepsin. Bromelain is used commercially to tenderize meat and chill-proof beer. The bromelain may account for the belief that pineapples are good for our digestion.
Getting a field of pineapples to produce a crop simultaneously (to avoid repeated, labor intensive harvests) has always been a problem. Months could pass before a plant next to a fruiting one comes into flower. During the early 20th century, pineapple growers found that fields where smudge pots had been used to prevent frost damage flowered and fruited uniformly. By the 1930’s it was known that ethylene (a by-product of combustion) was responsible for the uniform flowering, and that similar compounds such as acetylene or the plant hormone auxin could do the same. Shortly thereafter the practice of dropping a few granules of calcium carbide onto the growing point of pineapple plants developed. Calcium carbide reacts with water to yield acetylene. Today, the ethylene releasing compound ethephon is sprayed onto pineapple plants to promote uniform flowering.
The cultivation of pineapples has become an exact science. For best fruit quality the plant has specific environmental requirements such as mineral rich soil that is moist but well drained, low humidity, full sunlight, and temperatures that do not get below 32F or above 90oF. This environment can be found in many tropical countries, and the pineapple industry is significant in Thailand, the Philippines, United States (Hawaii), Mexico, Ivory Coast, South Africa, Malaysia, Kenya, Taiwan, Australia, and other countries. Interesting enough, prior to 1950 Hawaii produced 70% of the world’s pineapples. Increasing production costs and foreign competition has reduced Hawaii’s market share to less than 30%. Still, Hawaii produces 500,000 tons of pineapples each year.
Besides its use as a food, the pineapple fruit has a long history of symbolism that persists today. When first cultivated in European greenhouses in the 17th century, it was used only by the wealthy to adorn banquet tables. It became a status symbol of the social elite. During the Napoleonic Wars, English caricaturists used the fruit to symbolize high living and opulence. European colonists carried the pineapple symbol back to the Americas to represent “friendship” and as an image of “welcome”.
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