Kiwi fruit (Actinidia chinensis) has a beautiful green flesh which almost shines out with its goodness. Kiwifruit are commonly reported to be a good source of vitamin E and in addition contain phenolics and carotenoids. One of the most popular products using kiwi fruits is the fruit leather which is fruit puree concentrate that is dehydrated to a point where it forms a pliable food stuff. As the name suggests, it has quite a leathery texture but is full of vitamins, minerals and fibre.
Nowadays kiwi fruits are recommended for a host of health issues, especially constipation.
In reality it is actually a large berry with edible seeds. The peel can be consumed but it is not as tasty as the pulp/flesh.
A large body of research has been conducted by the Horticulture and Food Research Institute of New Zealand in Auckland, New Zealand.
Kiwi Fruit Nutrition
A medium sized kiwi fruit contains on average 2.5 grams of fiber with plenty of vitamins, minerals and other nutrients that are important for maintaining good health. The greatest benefit is helping us maintain our digestive system.
Kiwi Fruit Componentry
Kiwifruit pulp contains plenty of phenolic compounds which has been examined using reversed-phase HPLC (Dawes & Keene, 1999). The clarified juice contains between 1 and 7 mg/l. Heat treatment of the juice produces derivatives of these phenolics which implies that processing has a positive impact on the fruit.
Most of these are derivatives of coumaric and caffeic acids. Compounds of note include chlorogenic acid, protocatechuic acid, and a derivative of 3,4-dihydroxybenzoic acid. Epicatechin, catechin and procyanidins ((B3, B2, or B4 and oligomers) have also been identified.
The flavonols are glycosides of quercetin (glucoside, rhamnoside, and rutinoside) and kaempferol (rhamnoside and rutinoside).
The flavonol glycosides are suggested as the best markers of key fruit and a way of identifying adulteration.
The proanthocyanidins in what is the pulp (pericarp) were separated into three fractions (Chai et al., 2014). A combination of analytical methods including MALDI-TOF MS and HPLC-ESI-MS revealed a complex mix of of B-type propelargonidins, procyanidins, procyanidins gallate, and prodelphinidins. These components strongly inhibit tyrosinase which is often involved in enzymatic browning reactions when released into pulp. All these components also have very strong antioxidant activity.
A number of researchers postulate that kiwi fruit pericarp proanthocyanidins could serve as insecticides, food preservatives, and cosmetic additives.
The fruit also contains chlorophylls a and b and the carotenoids normally associated with photosynthesis, β-carotene, lutein, violaxanthin, and 9‘-cis-neoxanthin. Generally, all the kiwi fruit species contains these components but A. chinensis also contains esterified xanthophylls (McGhie & Ainge, 2002).
Kiwifruit is noted for its extremely firm texture. Poor storage and handling however will often reduce the value of the fruit when it is damaged and bruised. The fruit is often used, sliced in high end fruit salads. Pre-treatments maintain texture relatively well (Costa et al., 2006). A mild heat treatment by immersing the fruit in water for about 40 minutes at temperatures just below 45 ºC appears to be optimal. Kiwi fruit can be turned successfully into a fruit leather
Treatment For Constipation
Numerous anecdotal reports comment that kiwifruit has laxative effects. For many it would be an acceptable alternative to taking senna even as a dietary supplement, especially for the elderly who often experience constipation (Rush et al., 2002). It has been reported that the dietary fiber in kiwifruit is about 3.4 g/100 g, so it is a good source of dietary fiber. One study in Chinese patients found that the fibre from kiwi fruit helped with alleviating constipation (Chan et al., 2007).