Kiwifruit - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 472

kiwifruit may have some drawbacks such as the follow-
ing: (1) the quality characteristics of the fruit are liable to
deterioration during the course of processing and storage;
(2) chlorophylls (major pigments in kiwifruit) may convert
to pheophytins and pyropheophytins, resulting in the loss
of its green color (Schwartz and Lorenzo, 1991); and (3)
ascorbic acid loss and cell wall destruction occur during
processing steps (Llano et al., 2003).

kiwifruit that does not meet the fresh fruit standards are gen-
erally used to produce processed products such as canned
kiwifruit, frozen pulp, dried kiwifruit slices, kiwifruit juice,
wine, distilled kiwifruit liqueur, jam, leather, and vinegar.
However, interest in adding value to the fruit and promoting
its health benefits and technological advantages of some of
its components have attracted to utilize kiwifruits for other
applications (Kawase et al., 2001; Rush et al., 2002; Hunter
et al., 2008; Parkar et al., 2010).
Kiwifruit processing is relatively important in China
since storage and transport systems are not sufficient to
cope with the production. Between 20% and 30% of all
Chinese kiwifruit production is currently being processed

Preparation operation
The general processing steps for the preparation of kiwifruit
for further processing are outlined in Table 25.2. Rejected

Table 25.2. General preparation and processing steps for kiwifruit.

Step Description

Sorting/grading To remove substandard fruit (with molds or diseases) and all foreign bodies

Washing/cleaning/brushing the hair To remove all impurities which cannot be eliminated at the processing step in

finished products
-

Wash additives to cleanse and reduce bacterial count according to regulations
and requirements

- Hair removal processes may be employed prior to any optional cleaning or

grading steps

Peeling/skin removal To remove the skin that might contain substances adversely affecting the taste and

qualities of kiwifruit products
- Peeling and slicing of kiwifruit caused an increase of more than 30% in mass

loss after 3 days storage in comparison with unpeeled slices; however, the
effect of wounding on the ethylene and CO 2 production rates were higher
when the peel was not removed (Agar et al., 1999)

Cutting Has a better utilization of preservation “space” in receptacles and is not

mandatory; this will be defined by customer/supplier agreements/standards; this
operation is preferably performed by mechanical means
- Cutting direction is important in the wounding response of the fruit

Blanching To soften the fruit tissues before refining

-

Require a short heat treatment to inactivate enzymes and stabilize quality
during preservation and storage

Blanching in hot water (70 ◦ -100 ◦ C) or steam is a preliminary step to freezing
or dehydration of kiwifruit

-

- Advantages: destruction of micro-organisms, inactivate enzymes involved in

quality deterioration of the processed products (peroxidase, lypoxygenase,
polyphenoloxidase)

- Disadvantages: structural changes caused by blanching such as swelling of cell

walls and increases in the extent of cell-cell separation in the middle lamella,
loss in flavor, color, and nutritional quality (Gerschenson et al., 2001; Llano
et al., 2003)

Preservation Carried out by chemical means, by freezing, or by pasteurization

Source: Adapted from (FDA, 2009).