The Kiwi (Aka Thekiwifruit)

The Kiwi (aka - The Kiwifruit)

The summer of 2008 was the first time I had ever tried a kiwi. I had venomously steered clear of that hairy brown egg with the green insides and little black things that looked like the fruit was either going bad or just plain tasted bad. After biting into a piece, I realized what a tasty little piece of goodness this was that I had been avoiding all my life. Armed with my newfound fondness for this tasty little treat, I decided to choose it as my fruit to investigate. As I began my research, I was expecting only a little bit of information, yet to my surprise, the world has long known about the goodness that this fruit packs and information abounds. Below is a summary of this wealth I have found, which in itself will be challenge to compress into such a small report.

The Kiwifruit, lovingly known in North America as the kiwi, originates from China. The name itself has undergone a few transformations, from being called the Chinese Gooseberry until after WWII and then once heavy importations started into North America; it was briefly called the melonette. Across the globe, New Zealanders and Australians began calling it the kiwifruit to not confuse it with the national (flightless) bird (The Kiwi) of New Zealand or the locals but it was shortened to kiwi in North America. Taxonomists prescribing formal nomenclature labeled this fruit Actinidia deliciosa and placed it in the Actinidiaceae family. Italy is currently the global behemoth when it comes to highest kiwifruit production, and New Zealand follows in second place. It should be noted that while there are a number of varieties, although only a handful make up the bulk of global production. As such, the cultural practices and cultivation descriptions that follow in this paper will primarily focus on Actinidia deliciosa. Newer and different varieties are becoming popular that are tolerant to Canadian climates, which will be discussed in closing. Furthermore, for the purpose of this discussion, either kiwi or kiwifruit will be used as a common name.

The fruit itself commonly looks about the size of a large farm egg, and has a light brown furry skin. The hairs are very short and slightly matted. Open the fruit up and you will find a bright green fleshy interior with a small population of tiny black seeds closer to the center. The fruit has no core and as such can be eaten whole. From my personal experience, the skin is seldom eaten, as it apparently tastes sour or tart and let’s be honest – it’s hairy. Generally the fleshy inside tastes sweet, with a touch of tart and is lightly juicy but not to the point of being messy.

The fruit has a natural protein-dissolving enzyme in it that can double as a meat tenderizer. Before I continue on about the benefits (of which there are numerous) to eating this fruit, I should point a small cautionary note. The potential here is that this enzyme, called actinidin, can be a severe allergen to some people (usually children) whereby symptoms that follow may include, sore mouth or tongue, sweating, swelling of the face, tongue, or mouth, a body rash, or vomiting and stomach pains. There have even been noted cases of severe breathing difficulties, to the point of collapse. People who would likely be so afflicted would also like be allergic to pineapples, papaya and latex.

Despite the fact that a few that may be allergic to this fruit, the kiwi is actually the most nutritious common fruit by weight as demonstrated by a study at Rutgers University. By weight, the kiwi was shown to contain more potassium than a banana and more Vitamin C than the orange. The kiwi is also bountiful in Vitamins B1, B2, B3, B6, B9, protein, fiber (soluble and insoluble), magnesium, iron and calcium.

From a medical standpoint, beyond nutrition, Kiwi also contains a phytonutrient called lutein, which some studies claim to reduce the risk of cancer (lung, prostate), heart disease, and macular degeneration (a geriatric disease of the eyes). The kiwi is also high in carotenoids and phenolic compounds which are good for healthy blood, cardiovascular health and healthy hearts. The kiwi contains copper which promotes red blood cell formation. Studies have also demonstrated that the regular consumption of kiwi also works to thin blood, thereby reduce clotting, and lower fat that can cause arterial blockage, while not adversely affecting cholesterol levels. These same studies claim that the kiwi is a suitable substitute for daily dosages of physician prescribed aspirin. The extract from the kiwi is also good for relieving digestion problems, constipation, indigestion and irritable bowel syndrome. For athletes, the kiwi contains a high level of electrolytes which are great for replenishing lost nutrients through intense exercise or sweating (i.e. who needs Gatorade?). More studies have shown that the kiwi has high levels of serotonin, which is a natural anti-depressant with anti-anxiety benefits. There is also a natural sugar alcohol in the kiwi which is called inositol. Some researchers believe that this sugar is a beneficial treatment of depression and will also help to regulate diabetes. Did I mention the kiwi also tastes delicious? Now that we know why we should eat the kiwi, it becomes important to show how this fruit is grown.

For the most part, the kiwi is regarded as a subtropical plant, in that it does not like cold temperatures much below freezing. Spring frosts are known to damage the tender leaves, which in turn lead to limited flowering and fruiting or none at all. Intense winds can also damage tender growth so windbreaks are recommended where possible and should be planted perpendicular to prevailing winds. The kiwifruit grows on a vine and is usually trained to grow horizontally on a T-trellis to maximize fruiting and provide structural support for the weak branches that would not normally be able to support heavy fruiting. Most varieties are generally dioecious, and as such require a male in the vicinity to pollinate the females to bear fruit (1 male per 8 females). The kiwi plants are laid out in a row style with orchard sod in the laneways to suppress weeds, and bare soil in a 5ft band under the plants themselves. Weeds in the bare soil are often treated with an herbicide or very light cultivation as the kiwi roots can be very shallow.

A rule of thumb is that the kiwi will require about 220 frost free days for adequate leafing out, fruiting and ripening. Generally, leaves start to show in late March (late frosts are a big issue and this is why Canada is not a dominant producer of the traditional kiwi) and flowering commences in late May leading to ripened fruit by early November. When trained properly, the vines can produce several tones per hectare, but will require irrigation, and frost protection. They require diligent pruning (in summer for vegetative growth and winter for thinning of canes) to contain growth and promote fruiting that occurs on old growth only. Fruiting lessens as each cane or branch ages, so methodical pruning is practiced frequently that removes older canes (canes should be less than 4 years old for best results).

The kiwi vines generally like to grow in a soil that is lightly acidic (pH 6-6.5) and care should be taken to make sure that root-rot nematodes are free from the soil prior to establishment, because other than that, this plant has little in the way of pests. Light, balanced fertilizations are best applied in the early-late spring as summer feedings promote late season vegetative growth. As the vines age, the strength of fertilizations can decrease. Kiwi vines are quite sensitive to chloride, so that should be avoided when feeding and watering.

Vines tend to produce fruit on the 4th season, and are fully mature by the 10th. Fruits may reach proper size by late August, but will need to mature on the vine until November. Fruits are harvested by measure of their sugar content (6-8% on the vine) and when the seeds have turned black. When the fruit is ready to eat, it should have 12-15% sugar. Fruit can be stored at temperatures around the freezing mark but not too much above or below. Caution should be taken to ensure that ethylene producing fruits are not stored in the same vicinity as kiwi’s as this will hasten the ripening. Kiwifruits are harvested like a determinate crop (all at once) in a commercial setting, but harvesting can be staggered in a smaller setting by picking larger fruits first.

Research out of New Zealand has just identified the genetic characterizes of the Kiwi and as such the DNA mapping has now been completed of thousands of different gene sequences. One of the implications this has is that new varieties may be bred for increased health benefits or variety in taste. To think that they could make this fruit any healthier is something to behold, provided this doesn’t have the sour taste of GMO’s

In Canada there are some small varieties that are winter hardy, which not surprisingly are called the hardy kiwi. New names are currently being discussed for marketing purposes. Owing to the fact that it can tolerate Zone 4 conditions, and it actually needs the dormant period to produce fruit, it has been growing in Manitoba and in the Niagara region. The skin is edible and contains much of the same benefits of the hairy cousin. I found out that they are sold at the 100-mile store in Creemore, Ontario, so maybe I will have the chance to go up there and try some out if they still have some on the shelves. I am very glad to have had the chance to research this fruit as my father has Parkinson’s and as a result of his prescription drugs, the side effects he faces may be reduced from the many benefits this fruit offers.

Reference List

Kiwifruit (2009, January) Wikipedia, The Free Encyclopedia. Retrieved January 25, 2009, from http://en.wikipedia.org/wiki/Kiwifruit

Mainland, Charles M., Fisk, Connie, (Sept. 2006) Kiwifruit, Department of Horticultural Science, North Carolina State University (http://www.ces.ncsu.edu/depts/hort/hil/hil-208.html

Growing Kiwifruit, (2008) The Royal Horticultural Society, Retrieved on January 25th, 2009 from http://www.rhs.org.uk/advice/profiles0607/kiwifruit.asp

Vibrant green Kiwifruit boast key nutrients, (August 2003) Environmental Nutrition, Retrieved Sunday January 25th, 2009 from

http://findarticles.com/p/articles/mi_m0854/is_/ai_n18616101

Mellor, Colleen, (n.d.) Fuzzy kiwi cousin comes to Canada, Farm & Country retrieved on January 25th, 2009 from http://www.agpub.on.ca/text/crop_m12.htm

Kiwi Fruit Cultivation (2007), Kiwi-fruit.info, retrieved January 25th, 2009 from

http://kiwi-fruit.info/kiwi-fruit/Kiwi+Fruit+Cultivation

"Study Shows Benefits of Kiwifruit in Heart Health Are Similar to Aspirin According to the California Kiwifruit Commission” (Sept 2004) Business Wire,

Retrieved January 25th, 2009 from http://findarticles.com/p/articles/mi_m0EIN/is_2004_Sept_7/ai_n6183717

Morton, J. 1987. Kiwifruit. In Fruits of Warm Climates. (pp. 293–300). Miami. Florida Flair Books,

Kiwi Fruit, (2007) Retrieved January 25th 2009 from http://www.nutritiousfruit.com/kiwi-fruit.html