Continuation of the article published in R.F.C. of A. Newsletter, March and May 1985

Marketing and Grading, continued from Part II

The fruits are also graded according to their appearance, quality and condition as follows:
Grade 1. Fruits of similar varietal characteristics, mature, not overripe, clean, well-trimmed, fairly well-formed, free from soft bruises, decay, worm holes, growth cracks, cuts or other skin breaks and damage caused by discoloration or scars, diseases, insects, mechanical injuries or other means. Incident to proper grading and handling, a tolerance of 10 per cent by count of fruits in any lot may fail to meet the requirements but must conform to the requirements of the next lower grade.

Grade 2. Fruits of similar varietal characteristics, mature, not overripe, reasonably clean, well-trimmed, not badly misshapen, free from soft bruises, decay, worm holes, growth cracks, cuts or other means. Incident to proper grading and handling, a tolerance of 10 percent by count of fruits in any lot may fail to meet the requirements.

Uses and Food Value
The jak fruits may be utilized at nearly all stages of development. The immature fruit may be used as a vegetable. The food composition of immature jak fruits is shown on Table 12.3 which indicates that it is a good source of carbohydrates, calcium and phosphorous. As a vegetable, it makes an appetizing dish when grated and cooked with coconut milk, a very popular recipe especially in the Bicol region because of its distinctive flavor. In Sri Lanka, the jak is curried in coconut milk or simply boiled with seed and eaten.

The ripe fruit contains about 25 percent edible portion (pulp), 10 percent seed and 65 percent skin and other non-edible parts. The pulp is usually eaten fresh as a dessert. Chilling improves its flavour and makes it more crispy. The jak fruit is also made into preserves and other sweets, is utilized as a flavoring for ice cream and as ingredient for ginataan, a favorite native delicacy. It may also be mixed with fruit salad; it makes a delicious dish when mixed with boiled coconut milk and sugar. It may also be fermented and distilled for an alcoholic beverage.

Table 12.3 shows the food composition of the ripe pulp. Similar values have been reported earlier in the Philippines and in India.

The seeds taste delicious either boiled or roasted, and are very rich in starch. Its food composition is also shown in Table 12.3. Flour may be made from the mature seeds. Boiled seeds are also made into a delicious sweet.

The 'rags' are very rich in pectin and are ideal material for jelly-making. Table 12.4 shows its food composition.

The tree itself is much valued for its timber which is used in India for making furniture, building materials and musical instruments. In the Philippine province of Cebu, the wood is a prized material for making guitars, ukuleles and other musical instruments. The timber is strong and durable, beautifully marked and takes excellent polish. In India, the leaves of the jak tree are stitched and used as plates and other containers. A yellow dye, obtained by boiling mature wood or sawdust, is used for dyeing garments. The skin of green fruits, the bark of the tree and the leaves yield a white latex which may be collected and used for caulking boats, cementing broken china and trapping birds.

The latex from the fruit has 23.2 percent moisture and when dissolved in acetone yields 71.8 percent resins consisting of 8.5 percent albanes and 63.2 percent fluavilles. The resin constants are as follows: saponification number, 46.18; acid number, 5.64; ester number, 40.54; and melting point, 55.5°C. The resin may be used as a varnishing material. The bark also gives a darkish, water-soluble resinous gum.

Various parts of the jak plant have medicinal properties. The ash of the leaves is applied on wounds and ulcers as cicatrizant. A root decoction is used for diarrhea and fever. The latex is used for glandular swellings and snake bites; or it is mixed with vinegar and applied to these swellings and diseases to promote suppuration. The ripe fruit is demulcent, nutritive and laxative. The starch of the seeds is used to treat bilious colic. The roasted seeds have aphrodisiac action.

Processing and Preservation
Jak pulp is commonly made into preserve. After extraction from the fruit, the seed is separated from the pulp. About ½ kg pulp is dropped in a boiling syrup made up of 2½ cups sugar and 5 cups water. Cooking is continued until the fruit becomes tender and transparent. The cooked pulp is placed in a previously sterilized jar while the syrup is allowed to thicken further. The thickened syrup is poured into the jar, the bubbles are removed, and the jar filled with the fruit is half-sealed and sterilized in boiling water for about 30 minutes. Then the jar is sealed tightly and allowed to cool and dry.

The pulp can also be dehydrated and candied by the conventional method of syruping with subsequent oven-drying. Studies have shown that irradiation decreases spoilage and improves the texture of candied jak. The critical moisture content for irradiation to be beneficial in reducing spoilage of the candied product is 27 percent. Irradiation improves the texture of the candied fruit when its moisture content is 20 percent or below.

The non-edible portion or 'rags' can be used for making jelly. This non-edible portion is boiled and strained to collect the extract. To 1 cup extract is added ¾ cup sugar. The mixture is boiled and its pH is adjusted to 3.0-3.3. The resulting jelly is poured into a sterilized jar and sealed.

Acknowledgement: Promising Fruits of the Philippines by Roberto E. Coronel. The book was kindly loaned by Mr. Gordon Vallance.

This concludes this series about Jakfruit.
Editor's note: Tables 12.3 and 12.4 were not found in these newsletter articles.