Pineapple - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 333

Preparation operations
The fruit is first unloaded by hand by dumping into water or
by hydraulic lifts, which raise the bins and gently unload the
fruit onto conveyors. Overripe and highly translucent fruit
sink in water dump/wash tanks since their density is greater
than that of water, and sometimes salt is added to increase
the density. These “sinkers” are removed separately. The
water in the dump/wash tanks is chlorinated. The fruit is
removed by hand or elevated out from the dump/wash tank
and passes under a spray of clean water. The fruit is then
presorted on a conveyor table to assess fruit quality, size
distribution, shell color, and to remove rotten, mechanically
damaged, and misshapen fruit. The fruit may pass under an
air drier either before or after this inspection and sorting.
The fruit in large packing operations is oriented in single
formation on the conveyors before passing to the waxer
and fungicide application by drenching or spraying onto
the fruit body only. Waxes are normally only applied to the
fruit as they can cause burning of the crown leaves. The
fruit again will pass through an air drier before arriving at
the color and/or size grader. Pineapples, after being graded
by weight, are then transferred to packing tables (Paull
and Chen, 2003). If the fruit is destined for canning or
minimal processing the above process is varied with no
wax or fungicide being applied and the fruit being graded
on diameter to fit the Ginaca machines that remove the skin
and fruit core (Hepton and Hodgson, 2003).

cylinders that have low natural levels of acid. The cans are
filled with the packing medium (natural juice, light syrup
14 ◦ -16 ◦ Brix, or heavy syrup 18 ◦ -22 ◦ Brix) and treated in
an exhaust box, in which the product is heated above 60 ◦ C
to prevent any microbial growth in the medium, and is sub-
jected to vacuum to remove entrapped air from the tissues.
Finally, cans are sealed, autoclaved, cooled, labeled, and
boxed to be ready for distribution (Hepton and Hodgson,
2003). The table-end materials are used to produce crushed
pineapple, which requires a much heavier drained weight
than that of slices and chunks. The heavier drained weight
is achieved by heating before filling the cans as the excess
juice released in the cooking process is eliminated. Figure
18.4 shows a typical pineapple canning process flowchart.

Pulp
Pulp is the product obtained from peeled pineapple by
crushing. Pulp may be preserved by thermal treatment and
by adding preservatives. It is packed into small and bulk
lots for further industrial processing and formulations in
ice cream mixes, jellies, jams, and sodas. The pulp can be
heat sterilized and packed aseptically, leading to a product
with a long shelf life without any added preservatives.

Concentrated frozen pulp
This is the product from thermal treatment of the pulp
in which at least 50% of the initial water content is re-
moved. Concentration and freezing preserve the pulp for
an extended period of time. The concentrated pulp is sta-
ble without the addition of chemicals as long as it is kept
frozen. On reconstitution with clean water, the pulp should
have a similar quality to the original pulp.

Processing
Canning
Fruit weighing 1.5-2.0 kg are best suited for canning as
rings. Conveyor belts carry the fruit to the Ginaca machine
and center each fruit over the sizing knife, which splits
the shell, allowing a cylinder to pass through the circular
knife. The resulting pineapple cylinders, without the shell
and the core, proceed to trimming tables, which are set
up as either slice tables (for slices, tidbits, crushed fruit,
and juice) or chunk tables (for chunks, crushed fruit, and
juice) and where inspectors manually remove blemished
pieces and any adhering shell or eyes. The cylinders are
then conveyed to the slicer. The edible trimmings are placed
on conveyor belts headed for the juice preparation area, and
inedible portions (all materials with skin or blemishes) are
separated and pass on to the by-products manufacturing
area.
Slices graded on size, color, and maturity are finally
canned or cut to produce chunks, tidbits, cubes, and chips.
ApHof

Frozen slices
Prior to freezing, a blanching medium pretreatment of 17%
TSS sucrose solution, 1,493 mg/liter calcium chloride, and
300 mg/liter ascorbic acid is added to maintain the texture,
color, and water syneresis in the frozen slices (Chauhan
et al., 2009). Frozen slices following this processing have
a shelf life of at least a year (Bartolome et al., 1996), with
minimal changes in the soluble solids and sugar content
(fructose, glucose, and sucrose).

Dried pineapple
Chunks, slices, or juice are dehydrated to a final moisture
content of

5%, which allows the product to have a longer
shelf life when packed in a nonpermeable container or bag
and held at ambient temperatures and minimal temperature
abuse. The addition of maltodextrin minimizes product cak-
ing during drying (Jaya and Das, 2009). This dried product

∼

4.6 is required if packed as a high-acid product.
If necessary, citric acid can be added if there are individual

≤