Almost all kiwifruit in commerce belong to a few cultivars of Fuzzy Kiwi (
A. deliciosa): 'Hayward', 'Blake', and 'Saanichton 12'.
They have a fuzzy, dull brown skin, and bright green flesh. The familiar cultivar 'Hayward' was developed by Hayward Wright in Avondale, New Zealand around 1924.
It was initially grown in domestic gardens, but commercial planting began in the 1940s.
Hayward is the most commonly available cultivar in stores. It is a
large-egg shaped fruit with a sweet flavor. Saanichton 12, from British
Columbia, is somewhat more rectangular than Hayward and comparably
sweet, but the inner core of the fruit can be tough. Blake has a smaller
more oval fruit, and the flavor is considered inferior.
The most common male pollenizer for these varietals is the Chico.
The golden kiwi (
A. chinensis)
has a smooth bronze skin, with a beak shape at the stem attachment.
Flesh color varies from bright green to a clear, intense yellow. This
species is sweeter and more aromatic in flavor, the flavor reminiscent
of some subtropical fruit. Its short storage life currently limits its
commercial potential. One of the most attractive varieties has a red
'iris' around the center of the fruit and yellow flesh outside. The
yellow fruit fetches a higher market price and, being less hairy than
the fuzzy kiwi, is more palatable for fresh consumption.
A commercially viable
variety of this red ringed kiwi has been patented as the EnzaRed™, and is a cultivar of the Chinese "hong yang" variety.
Hort16A, marketed as Zespri® Gold, is a golden kiwifruit now marketed worldwide in increasing volumes.
kiwifruit is rich in the protein-dissolving enzyme actinidain (in the same family of thiol proteases as papain), which is commercially useful as a meat tenderizer.
Actinidain also makes raw kiwifruit unsuitable for use in desserts
containing milk or any other dairy products which are not going to be
served within hours, because the enzyme soon begins to digest milk
proteins. This applies to gelatin-based desserts as well, as the
actinidain will dissolve the collagen proteins in gelatin very quickly,
either liquifying the dessert, or preventing it from solidifying.
To overcome this effect, the United States Department of Agriculture suggests cooking the fruit for a few minutes before adding it to gelatin.
Sliced kiwifruit has long been regularly used as a garnish atop whipped
cream on the common New Zealand and Australian dessert, the pavlova. It can also be used in a variety of other savoury and sweet dishes.
The actinidain found in kiwifruit can be an allergen for some individuals.
Specifically, people allergic to latex, bananas, papayas, or pineapples are likely to also be allergic to kiwifruit. The fruit also contains calcium oxalate crystals in the form of raphides.
Reactions to these chemicals include sweating, tingling and sore mouth
or throat; swelling of the lips, tongue and face; rash; vomiting and
abdominal pain, heartburn; and, in the most severe cases, breathing
difficulties, wheezing and collapse. The most common symptoms are
unpleasant itching and soreness of the mouth, with the most common
severe symptom being wheezing. Severe symptoms are most likely to occur
in young children.
Kiwifruit is a rich source of vitamin C (1.5 times the United States DRI per 100 grams) and vitamin K, and a good source of dietary fiber and vitamin E.
The fruit and skin contain flavonoids, actinidain, and adhered pollen, which may produce irritation in the mouth and throat of some allergic individuals.
Kiwifruit seed oil contains on average 62% alpha-linolenic acid, an omega-3 fatty acid. Usually a medium size kiwifruit provides about 46 calories,
0.3 g fat, 1 g protein, 11 g carbohydrates, and 2.6 g dietary fiber found partly in the edible skin.
Kiwifruit is often reported to have mild laxative effects, due to its significant levels of dietary fiber.
Kiwifruit contains carotenoids, such as provitamin A beta-carotene, lutein and zeaxanthin.
Kiwifruit components, possibly involving vitamin E and omega-3 fatty
acids from its numerous edible seeds, have potential properties of a
natural blood thinner.
A study performed at the University of Oslo in Norway reported that
consuming two to three kiwifruit daily for 28 days significantly reduced
platelet aggregation and blood triglyceride levels (similar to popular mainstream aspirin therapy), potentially reducing the risk of blood clots.
