THE CANISTEL
SCIENTIFIC NAME: Pouteria campechiana
FAMILY: Sapotaceae
INTRODUCTION
As a result of recent reports in the popular press, on the radio, and exhibitions, there has been an unprecedented interest in cultivating more exotic types of fruits in South Africa. We have looked at a number of these fruits with the idea of starting small commercial industries to allow farmers to diversify, especially in situations where some of the more traditional fruits are close to over-production. The canistel appears to be one such fruit that has the potential to develop a small commercial industry.
The canistel is the showiest fruit of the family Sapotaceae but has generally been under-evaluated, both in horticultural literature and by those who have a casual acquaintance with it. It is sometimes erroneously recorded as native to northern South America where related, somewhat similar, species are indigenous. Apparently it occurs wild only in southern Mexico, Belize, Guatemala, and El Salvador (Morton, 1987). Colloquial names applied to this fruit include: egg-fruit, canistel, ti-es, yellow sapote (Morton, 1987).
CLASSIFICATION
The canistel, Pouteria campechiana Baehni, has been the subject of much botanical confusion as evidenced by its many synonyms: P. campechiana var nervosa Baehni; P. campechiana var palmeri Baehni; P. campechiana var salicifolia Baehni; Lucuma campechiana HBK.; L. heyderi Standl.; L. laeteviridis Pittier; L. multiflora Millsp.; L. nervosa A.DC.; L. palmeri Fernald; L. rivicoa Gaertn.; L. rivicoa var angustifolia Miq.; Richardella salicifolia Pierre; Sideroxylon campestre T.S.Brandeg.; Vitellaria campechiana Engl.; V. salicifolia Engl.
The canistel is closely related to the lucmo and abiu (Scholefield, 1984). The abiu, Pouteria caimito Radlk (syns. Lucuma caimito Roem. and Schult.; Achras caimito Ruiz and Pavon) is also occasionally known as the yellow star apple. The lucmo, Pouteria lucuma O.Ktze. (syns. P. insignis Baehni, P. obovata HBK., Lucuma obovata HBK.) is also known as lucuma, lucumo and mamon (Morton, 1987).
DISTRIBUTION
The canistel is cultivated in its countries of origin and also in Costa Rica, Nicaragua, Panama, Puerto Rico, Jamaica, Cuba, the Bahamas, and Florida (Morton, 1987). Trees that were planted from fruit bought in Cuba are growing in Colombia. The canistel is also included in experimental collections in Venezuela. The tree was introduced at low and medium elevations in the Philippines before 1924 and it reached Hawaii probably around the same time. Attempts to grow it in Singapore were not successful. In 1949 there were a few canistel trees growing in East Africa (Morton, 1987).
DESCRIPTION
Tree
The tree is erect and generally no more than 8 m tall (Ruehle, 1967; Morton, 1987). However, in favourable conditions the tree can reach 20 to 30 m with a trunk diameter of 1 m (Scholefield, 1984 Morton, 1987). The tree is slender in habit or with a spreading crown, it has brown furrowed bark and abundant white, gummy latex (Ruehle,1967; Morton, 1987). Young branches are velvety brown (Morton, 1987).
Leaves
The bright green and shiny leaves are alternate but mostly clustered on newer growth at the ends of the branches (Ruehle,1967; Morton, 1987). The leaves are relatively thin, short to long-stemmed, oblanceolate, lanceolate-oblong, or obovate, bluntly pointed at the apex, more sharply tapered at the base, 110 to 280 mm long and 40 to 80 mm wide (Morton, 1987).
Flowers
The flowers are small and borne in clusters or solitary in the leaf axils or at leafless internodes of young wood (Ruehle, 1967; Morton, 1987). The flowers have slender pedicels and are five to six-lobed, green to cream-coloured, silky-hairy and approximately 8 to 11 mm long (Scholefield, 1984; Morton, 1987). The flowers are bisexual and fragrant (Morton, 1987).
Flowering extends from January to June in Mexico. In Cuba, flowers are borne mostly in April and May although some trees flower throughout the year (Morton, 1987). The fruit is extremely variable in shape and size, and may be nearly round, with or without a pointed apex, or it may be somewhat oval, ovoid, or spindle-shaped. It is often bulged on one side and there is a five-pointed calyx at the base which may be rounded or with a distinct depression (Morton, 1987). Fruit length varies from 50 to 170 mm and diameter from 40 to 75 mm with a weight of up to 1.5 kg (Scholefield, 1984; Morton, 1987). Unripe fruit is green-skinned, hard and gummy internally. On ripening the skin turns lemon-yellow, golden-yellow or pale orange-yellow, is very smooth and glossy except where occasionally coated with light brown or reddish-brown russeting (Morton, 1987).
The fruit flesh is yellow to orange-yellow, mealy with a few fine fibres. The texture has been likened to a cooked, mealy, sweet potato or to the yolk of a hard boiled egg (Ruehle, 1967; Morton, 1987). The flavour is sweet and somewhat musky. The ripe pulp from some seedlings is less dry and mealy than others (Ruehle, 1967). Picking the fruit when mature, but several days before it softens, tends to reduce dryness of the pulp (Ruehle, 1967). The seeds, usually one to three, are ovoid to oblong 20 to 50 mm in length and 12 to 32 mm wide. They are hard, glossy, dark brown except on the straight or curved ventral side where they are dull light brown, tan or greyish white (Ruehle, 1967; Morton, 1987). Both ends are sharp-tipped (Morton, 1987).
The fruit matures mostly from November to February in Florida, but individual trees may produce fruits at other times (Ruehle, 1967). The fruits mature from September to January or February in the Bahamas. In Cuba, the main fruiting season is from October to February, but some produce more or less continuously throughout the year (Morton, 1987). The canistel thus appears to come in to production in late autumn and winter when few other tropical fruits are available.
Fruit Composition
Canistels are rich in niacin and carotene (provitamin A) and have a fair level of ascorbic acid (Morton, 1987). The Table gives the food value per 100 g of edible portion of the canistel.
Food value per 100 g of edible portion of canistel (Morton, 1987)
| Calories | 138.8 |
| Moisture | 60.6 g |
| Protein | 1.68 g |
| Fat | 0.13 g |
| Carbohydrates | 36.7 g |
| Fibre | 0.1 g |
| Ash | 0.9 g |
| Calcium | 26.5 mg |
| Phosphorous | 37.3 mg |
| Iron | 0.92 mg |
| Carotene | 0.32 mg |
| Thiamine | 0.17 mg |
| Riboflavin | 0.01 mg |
| Niacin | 3.72 mg |
| Ascorbic acid | 58.1 mg |
| Amino acids: | |
| Tryptophan | 28 mg |
| Methionine | 13 mg |
| Lysine | 84 mg |
VARIETIES
Great seedling diversity exists and some selections have been made but apparently no named cultivars exist (Scholefield, 1984). Certain types are so distinct that they have been recorded as different species in the past. The spindle-shaped form was the common strain in the Bahamas for many years. The rounded, broader form began to appear in special gardens in the 1940s, and the larger types were introduced from Florida in the 1950s (Morton, 1987).
In 1945, large, symmetrical fruits were being grown under the names Lucuma salicifolia and yellow sapote at the Agricultural Research and Education Centre and at Palm Lodge Tropical Grove, Homestead, Florida but these were later classified as superior strains of canistel (Morton, 1987). Some fruits are muskier in odour and flavour than others, some are undesirably dry and mealy, some excessively sweet. An excellent, non-musky, fine-textured, rounded type of medium size has been selected and grown on a ranch in Martin County, Florida. There is considerable variation as to time of flowering and fruiting among seedling trees (Morton, 1987). A selection programme has been initiated in Puerto Rico (Martin, 1976).
CLIMATIC AND SOIL REQUIREMENTS
Climate
The canistel is widely adapted and grows well in a tropical or subtropical climate (Scholefield, 1984). It is about as hardy as the sapodilla (Ruehle, 1967) which can withstand temperatures of -3 to -2°C for several hours. It has survived cold winters in areas of Florida but has never reached fruiting age in California. It is usually found up to elevations of 1400 m. It requires no more than a moderate precipitation and does well in regions that have a long dry season (Morton, 1987). The tree is fairly wind-resistant (Ruehle, 1967).
Soil
The canistel is tolerant of a wide range of soils - calcareous, lateritic, acid-sandy, and heavy clay. It grows well on deep, fertile well-drained soil but is said to be more fruitful on shallow soil. It can be cultivated on soil considered too shallow and poor for most other fruit (Morton, 1987), provided drainage is good (Scholefield, 1984).
Propagation
Propagation is usually by means of seeds (Ruehle, 1967). Seeds lose their viability quickly and should be planted within a few days after removal from the fruit. If decorticated, seeds will germinate within two weeks; otherwise there may be a delay of three to five months before they sprout. The seedlings grow rapidly and begin to bear within three to six years. There is considerable variation in yield, size and quality of fruits (Morton, 1987).
Vegetative production is recommended to hasten bearing and to reproduce the best selections. Side veneer, chip bud and cleft graft are commonly used (Scholefield, 1984; Morton, 1987). Air-layering has also been successful. Cuttings of mature wood will root but are extremely slow to root and this method is thus not often used (Ruehle, 1967; Morton, 1987).
Culture
As the canistel is not grown commercially, there is very little known about its cultural requirements. Mulching is beneficial in the early years. A balanced fertilizer applied at time of planting and during periods of rapid growth is advisable, but the tree does not demand special care. Outstanding branches should be pruned to avoid wind damage and to shape the crown (Morton, 1987).
Pests and diseases
Few pests and diseases attack the canistel. The only recorded pest is scale insects which were noted in Florida (Ruehle, 1967). In Florida, the leaves of the canistel are attacked by a rust (Acrorelium lucumae). Fruit spot (Colletotrichum gloeosporioides), leaf spot and scab (Elsinoe lepagei) and leaf necrosis (Gloeosporium) have also been recorded in Florida for the canistel. The tree is, however, generally nearly always vigorous and healthy (Morton, 1987).
HARVESTING AND STORAGE
Harvesting
Fruits should be harvested by hand when mature but still firm (Scholefield, 1984). The fruits should be clipped to avoid tearing the skin. If left to ripen on the tree, the fruits split at the stem end and drop. A severe drop in temperature will also cause firm, mature fruits to split and drop to the ground (Morton, 1987). Experience is needed to determine the correct stage for picking (Scholefield, 1984).
Storage
If kept at room temperature the fruits will ripen and soften in three to ten days. They should not be allowed to become too soft and mushy before eating. Ripe fruits can be kept in good condition in a refrigerator (ca. 4°C) for several days (Morton, 1987).
Freshly-picked, firm fruits have been successfully shipped from Florida to New York and Philadelphia. Unfortunately, no studies have been made to determine optimum temperature and humidity levels for long-term storage and shipment (Morton, 1987).
USES
Food Uses
The fruit is well liked by some for eating fresh, but is disliked by others because it is not crisp and juicy like so many other fruits (Ruehle, 1967; Morton, 1987). Some Floridans enjoy the fruit with salt, pepper and lime, lemon juice or mayonnaise, either fresh or after light baking (Morton, 1987). The pureed flesh may be used in custards or added to ice creams just before freezing. A rich milkshake is made by combining ripe canistel pulp, milk, sugar, vanilla and other seasoning (Morton, 1987).
Canistel pulp has also been used in preparing pancakes, cupcakes, jam and marmalade (Morton, 1987). The fruit can also be dried and processed into a powder which can be added to desserts and ice cream (Scholefield, 1984). Some companies in the Tropics have expressed interest in the processing of this fruit (Campbell, 1976).
Other Uses
Latex extracted from the tree in Central America has been used to adulterate chicle. The timber is fine-grained, compact, strong, moderately to very heavy and hard, and valued especially for rafters and planks in construction. The heartwood is greyish brown to reddish brown and blends into the sapwood which is somewhat lighter in colour. The darker the colour, the more resistant to decay (Morton, 1987).
Medicinal Uses
A decoction of the astringent bark is taken as a febrifuge in Mexico and applied to skin eruptions in Cuba. A preparation of the seeds has been employed as a remedy for ulcers (Morton, 1987). In 1971, a pharmaceutical company in California studied a derivative of the seed which seems to be active against seborrhoeic dermatitis of the scalp (Morton, 1987).
CONCLUSION
The Canistel would probably lend itself well to orchard cultivation if the necessary cultural research was done. However, the critical factor which will determine the success of any plantings is the market acceptability. This has not been determined, as most canistels which are sold on local markets are sold primarily to people of Latin American origin. During a recent visit to Chile, Dr J. Terblanche, previous Director of the ITSC, found canistels to be a common product on local markets. Development of such a crop will take a great deal of organized effort. Coordinated research in culture, harvesting, handling, shipping and processing is required if a profitable industry is to be established.
The Institute wishes to initiate and conduct feasibility studies on the Canistel with a view to possible commercialisation. However, this will involve the need to assess as wide a range of selections as possible, to investigate and develop management strategies for local conditions. The initial process in developing this crop will necessitate the assembling of a gene pool of the best selections from around the world. These selections can then be screened for climatic suitability, productivity, fruit quality and storage characteristics, product uses, consumer appeal and pest and disease susceptibility.
Only high quality fruit from selected cultivars should be marketed, and a strong consumer demand should be developed, fruit should be promoted, and the public informed and educated on the eating characteristics and potential of the fruit.
REFERENCES
Campbell, C.W., 1976. Present and future of minor tropical fruit species in Florida and similar areas. Acta Hort. 57: 89-95.
Johns, Leslie and Violet Stevenson, 1979. Fruit for the Home and Garden. Cornstalk, Sydney.
Martin, F.W., 1976. Introduction and evaluation of new fruits in Puerto Rico. Acta Hort. 57:105-110.
Morton, J.F., 1987. Fruits of warm climates. J.F. Morton, Miami, Florida. 505 pp.
Ruehle, G.D., 1967. Miscellaneous tropical and subtropical Florida fruits. Univ. Fla, Gainesville. 116 pp.
Scholefield, P.B., 1984. Canistel, Lucmo, Abiu. In: Tropical Tree Fruits For Australia. Queensland Dept Primary Industries. 226 pp.
DATE: November 1994
* * * * * * * * * * * * *
