Packing

A maximum pH of 4.6 is required if packed as a high-acid product. If necessary, citric acid can be added if there are individual cylinders that have low natural levels of acid.

Solid packs

A wide variety of styles of product may be packed from pineapple. The standard ones are listed in the excerpt from the Codex standards for canned pineapple (Codex Alimentarius Commission, 1995). These standards further describe types of packs, packing media, composition and quality criteria, including defects and their tolerances. Minimum requirements are also outlined for weights and measures and labelling of products entering international trade.

More specific standards may be outlined in national or other standards used to define expectations of specific packs. For example, the Campden Food and Drink Research Association has provided standards for canned pineapples, which can be used as criteria for packing and evaluating canned pineapple products (Campden Food and Drink Research Association, 1991a,b). Similarly, the US Department of Agriculture has published Standards for Grades of Canned Pineapple (USDA - Agricultural Marketing Service, 1990).

Details of the various standards are not listed here, but they should be used as references when setting standards for packing products of various styles to meet specific market requirements.

cylinder packs. Following the preparation of the cleaned fruit cylinders, whole cylinders to be used in cylinder packs are cut to a specified length to fit the cans in which they are to be packed. Whole cylinders may also be recut radially into spears or fingers of a length to fit the specified can size.

slices. Slices are graded by packers as fancy (geometrically perfect, excellent and uniform colour and whole), choice (not as perfect and with less colour) or standard, each grade to meet specifications. Slices are packed manually or automatically into cans. Slices may be further cut as titbits or cubes. For a graphic description of the cutting process, see Rohrbach and Johnson, Chapter 9 this volume.

Slice defects due to Ginaca malfunction include:

1. Off-centre: when the core hole is not centred in the slice to prescribed limits.

2. Off-centre core: when the core is not in the centre and the core hole is.

3. Off-core: when the core is in the centre and the core hole is not.

4. Large-core: when core tissues remain around the core hole

Since slice defects due to Ginaca malfunction affect maximum recovery of premium pineapple products, it is important to monitor and minimize slice defects. Other slice defects are due to:

1. The presence of too much core tissue.

2. Coarse texture from the upper portion of the cylinder and lighter colour from less mature fruit.

3. Physical damage, such as breaking, bruising or splitting.

4. Blemishes in excess of 1/16 in.

5. Gouges from removal of blemishes.

chunks and titbits. Chunks come from thicker slices, the dimensions of which will vary with the diameter of slices used. Chunks and titbits from slices of significantly different diameter, e.g. 1T and 21/ should not be mixed. If chunks or titbits are being produced, inspected slices may either proceed to the end of the table, where they are cut, or be placed in pans and taken to another location for cutting. Broken pieces and rejected slices pass over the end of the table (thereby, called table-end material) and are used in juice or crushed-pineapple preparation.

Once packed, the cans are filled with packing medium. This may follow treatment in an exhaust box, in which the product is heated and subjected to vacuum to remove entrapped air from the tissues. Packing medium is usually heated to above 60°C to prevent any microbial growth in the medium during its use.

The product is hermetically sealed under vacuum and then transferred to a cooker, where it is subjected to enough heat for a sufficient period of time to ensure that all organisms that could cause spoilage are killed.

crushed pineapple or crush. All table-end materials are gathered and conveyed to an inspection table, where all extraneous and off-quality material is removed. High-quality crushed pineapple should show discrete particles with no core or discoloured pieces due to the presence of skin or blemishes. Crushed pineapple may be designated for the retail or the institutional markets. Crushed products for the institutional market in the USA require a much heavier drained weight, which is achieved by heating before filling so that excess juice released in the cooking process may be drained away. As the cooking temperature is increased, more juice is released. There are two types of crushed-pineapple products for the institutional US market: coarse-cut and fine-cut, with the latter type requiring a heavier drained weight. After the proper drained weight is achieved, the product is heated to filling temperatures and hot-filled in no. 10 cans. Multiple rotary coolers are used to cool crush to 54°C.

After appropriate draining, crushed pineapple for the retail market is hot-filled at 86-90°C with a volumetric filler, inverted in the container, held for several minutes, depending on the size of the container, and cooled in rotary coolers to at least below 54°C.

Juice

Both solid and liquid fruit components from all Ginaca machines and trim tables are used in pineapple-juice production. Solid components consist of the following materials:

1. Pineapple cores: fruit centres removed by the Ginaca machines during peeling operations.

2. Eradicator meat: the thin layer of flesh between the shell and the fruit cylinder removed by the Ginaca machines.

3. Trimmings: end cuts from the Ginaca machines and fruit pieces from the trimming and preparation tables.

4. Whole fruit: the Sub 1T and other fruit sizes not required for solid packs or crushed.

The use of any other solid pineapple materials for juice production is not allowed for products sold in the USA. Any objectionable material is removed from the solid pieces over an inspection belt. These raw materials are then conveyed over screens that drain the free-juice component. Clean solid particles then pass through a disintegrator, which breaks down the pulp for easier juice extraction. A multiple-stage screw press is then used to extract pineapple juice from the solid constituents, maximizing recovery to about 90%. Juices from liquid components, consisting of all surplus juice obtained during any processing activity, and juice from the solid-fruit components are then blended with agitation in large tanks. When juice foaming occurs due to the presence of gums, up to 10 p.p.m. of food-grade antifoam may be added to reduce foaming. The juice is then heated in tube or plate heat exchangers to about 60°C and passed to continuous, automatic, desludging-type centrifuges to eliminate insect fragments, shell pieces and excess pulp. The insoluble-solids content of pineapple juice, which is important to the perceived mouth-feel of the product, is controlled by centrifugation in the range of 5-30%. Centrifuged juice is then stored in a tank equipped with an agitator and may be processed to produce single-strength pineapple juice, blended with other fruit juices or concentrates to produce juice blends used as packing medium, or evaporated to produce pineapple-juice concentrate.

Single-strength juice may be packed through a hot-fill process, cold-fill process or aseptic process. The hot-fill process involves filling the cans with juice preheated to about 96°C, seaming the can lids, inverting the cans, holding at this temperature from 1 to 3 min depending on the can size, and cooling to about 38°C. The cold-fill process involves filling the cans with juice at about 60oC, seaming the can lids, processing in continuous, agitating cookers to product temperatures greater than 87.7°C and cooling in continuous, agitating coolers to about 38°C. The aseptic process entails sterilizing the product and package separately, usually with the use of high-temperature, short-time heating and filling the sterile containers with sterile product under sterile conditions.

Pineapple-juice concentrate may be prepared using low-temperature, multiple-effect

(stages), tube or plate evaporators. Pineapple essence, usually obtained from the first effects, is added back to the final concentrate to enhance the flavour. Pineapple-juice concentrates, commonly sold as 41/2:1, 61°Brix, 3:1, 46.5°Brix, or 6:1, 72°Brix concentrates, are packaged in both aseptic and frozen forms. For a detailed description of pineapple-juice processing, please refer to Hodgson and Hodgson (1993).

Other products pineapple bran. Since approximately 35-40% of the fruit weight is in the skin and ends, proper solid-waste disposal becomes a serious consideration in pineapple-processing operations. The simplest solution that is currently followed by many processors is to return it to fields and use it as a soil amendment. Because of its high moisture content, it easily ferments and presents storage problems. To reduce this moisture content, other operations macerate the skin and ends to produce a coarse pulp and press out the liquid it contains - mill juice. The resulting solid material, called wet pineapple bran, is suitable for cattle feed. If dried to a moisture level of less than 12%, the product is known as pineapple bran, which can be easily stored.

mill juice. This is the liquid pressed from macerated pineapple skins during pineapple-bran production. Although it has a lower soluble-solids content and higher acidity than pineapple juice, mill juice has approximately the same composition but contains some undesirable flavour materials and heat-darkening agents, due to the Maillard reaction. Although an ion-exchange process is able to lower mill-juice acidity, an acid-modified pineapple juice cannot be designated as fruit juice by current US standards. Juice from other off-grade sources (e.g. rotten and damaged fruit) may be added to mill juice, concentrated and then added to wet pineapple bran to increase bran yield or may be used as a source of sugar in the production of alcohol and vinegar. When prepared under the same sanitary conditions as pine apple juice and if treated further to remove the off-flavour and off-colour components, mill juice has been successfully used as a sweetener in packing medium.

dietary fibre. Processed pineapple peels with 85% total fibre content and 1.0 kJ g_1, as prepared by the Institute de Investigaciones para la Industria Alimentaria, Havana, Cuba, were used as a source of dietary fibre at 8% maximum moisture in a dried beverage mix (Larrauri et al., 1994, 1995). A mild laxative effect is observed. Fibre from cores has been evaluated as a food-grade filler for some food products.

candied pineapple. Candied pineapple is probably one of the most popular dried-pineapple products. This product is generally prepared using pineapple chunks or thick pineapple slices segmented with a knife. The chunks are soaked for 5 h in sugar syrup (about 60°Brix) containing an antioxi-dant, such as ascorbic acid or a sulphiting agent, to maintain colour and are then air-dried (Fig. 11.2). The dried pieces are sometimes coated with another layer of syrup and dried again.

Candied pineapple segments, which had been blanched and vacuum-treated to reduce colour oxidation, appeared turgid and translucent, with no signs of significant cytor-rhysis but with severe plasmolysis. Its intracellular spaces were filled with liquid. Untreated candied samples appeared highly shrunken and opaque, with severe cytor-rhysis and plasmolysis, and its intercellular spaces were filled with air (Chen, 1995).

ultra-high-pressure pasteurized fresh cut pineapple. As a means of extending the shelf-life, fresh-cut pineapple chunks obtained from a commercial processor were packed in heat-sealed polyethylene pouches and treated under various ultra-high pressure (200, 270 and 340 MPa), temperature (approximately 4, 21 and 38°C), and time (5, 15, 40 and 60 min) combinations (Aleman et al., 1994). Bacterial survival and total yeast and fungi counts generally decreased with an increase in processing pressure.

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