In Malaysia, the popular canning varieties are Gandul and Hybrid 36 because these do well on peat. Elsewhere in the world, the Smooth Cayenne is preferred.

The fruit for canning should be cylindrical in shape, with square shoulders to minimise wastage during ‘coring' or fruit peeling. The preferred fruit size should weigh around 1.5-1.8 kg. A good canning variety should also have ‘shallow' eyes so that a thinner cut to remove the shell may be made to improve recovery. However Hybrid 36 and Gandul have fairly deep eyes and thick skin which make them less prone to bruising but their recovery is less than 20% compared with 24-30% for Smooth Cayenne.

Deep uniform golden colour is important as more high-priced ‘fancy' cuts can be recovered. Fibrosity in flesh should be minimum, but enough to prevent breakage of slices. High Total Soluble Solids in the fruit is also important as it reduces the sugar input.

For canning the Gandul is picked at ‘white-bract' stage while other varieties are harvested at 1-2 eyes-ripe stage. Unlike other varieties, Gandul does not keep well once the eyes show colour.

Canning

Harvested pineapples are immediately transported to the cannery in lorries or large bins to minimise bruising and fruit deterioration. To reduce losses due to spoilage, fruits should be processed within 24 hours after harvesting. Grading of fruit size is important to maximise recovery. The graded fruits are washed and then distributed in various size batches by conveyor belts to the coring machines fitted with Ginaca knives with appropriate diameter settings.

An operator regulates the feeding of pineapples to the Ginaca machines and manually removes cracked, smashed, fermented and other unsound fruits. The Ginaca machine centres each fruit over the sizing knife which splits the shell allowing a cylinder to pass through the circular knife. A rotating drum removes the shell and the fruit cylinder passes over a set of eradicator blades which strip off the juice material (juice blanket). It goes on into the first of a series of turrets which cuts off the two ends and the core of the cylinder. The cylinders are further cut to produce high value products such as slices, chunks, tidbits and crush. Each Ginaca machine can handle from 56 to 96 fruits per minute depending on fruit size.

Solid packs

When the pineapple cylinders arrive at the trimming tables set up as either slice or chunk tables, inspectors will check for blemishes and remnants of fruit shell on them and pare them off. The edible trimmings are used for juice while the fruit shell or blemished flesh pass on for making by-products. The pineapple cylinders are sliced and several products such as round cuts, tidbits, cubes and crushed pineapple are made. Thicker slices are cut as chunks or pieces. All these products are considered solid packs.

Juice

Solid and liquid fruit components from Ginaca machines and trim tables are used for pineapple juice production. Solid components include fruit cores, eradicator meat (thin layer of flesh trimming between the shell and fruit cylinder), trimmings of cut ends and fruit cylinders and whole fruits rejected for solid packs. The materials pass through a disintegrator which breaks down the pulp for juice extraction. A screw press is used to extract the juice. The juice is heated to 60°C and passed through a desludging centrifuge to eliminate unwanted fruit residues and foreign matter. The juice is controlled centrifuged to leave 5-30% of insoluble solids in the juice to give the important perceived ‘mouth-feel' of the product. The centrifuged juice is stored in tanks equipped with an agitator and may be processed as a single strength juice or blended with other fruit juices. The single strength juice may be subjected to evaporation to produce concentrates with strengths of 3:1 (46.5 °Brix), 4.5:1 (61 °Brix) or 6:1 (72 °Brix). Concentrates are packaged in both aseptic and frozen forms.

By-products

About 35-40% of the fruit is made of skin and non-usable trimmings from processing. These are macerated and the ‘mill-juice' pressed out. The residue called wet pineapple bran is suitable for cattle feed. When dried, the pineapple bran can be packed and stored for a long time as animal feed. The ‘mill juice' can be used to produce industrial alcohol, vinegar or a sweetener.