Wild mangos have fruit that are very fibrous, with high concentrations of 'turpentiney' resin. Some, such as M. quadifera have strong unidentified 'pungent' chemicals in the flesh. Some wild species are large, others small, with varying shaped fruit. The low fiber, relatively small stoned and resin free fruit we have today is the result of millennia of human selection. Mango seedlings are highly variable, so there was good opportunity for better sorts to arise as agricultural settlement commenced.
Mangoes need a dry period during fruit set; they also need subtropical to tropical conditions without frost. Spread was therefore mainly to the east, into Myanmar (Burma), Vietnam, and south. It is suspected that Portuguese merchants or travelers took the mango from India to east Africa, West Africa, and then to their colonies in the Americas, probably in the sixteenth century. Mangoes were grown in the West Indies in the eighteen century, and Florida in the nineteenth.
Mangoes have a relatively short shelf life, but the advent of air freight has meant mangoes can be exported from tropical South East Asia, Mexico, India and Africa and arrive in Europe and North America in excellent condition. However, given the cost of air freight, and the lack of extended shelf life, mangoes will always tend toward the luxury end of the market (except in countries where they can be grown locally). Which is a pity, because they are a particularly useful human food.
Not only are mangoes an excellent source of vitamin C (one fruit pretty much fills an adults daily vitamin C requirement), they also have the highest concentration of vitamin A of any commercial fruit listed here (an excellent 3,894 International Units per 100 grams of flesh).
Melon, Cantaloupe Cucumis melo
The melon is, like ourselves, an African. There are quite a few species of the genus Cucumis in Africa, and the wild melon that humans eventually domesticated is a native of sub Saharan eastern tropical Africa. It is believed to have been domesticated fairly late, relative to other crops, but once domesticated many and variable forms arose. It succeeded best in the drier, longer season parts of India and South West Asia; in fact it naturalized in India, and India is regarded as a secondary center of wild germplasm. From South West Asia it spread to Greece and Italy, and all parts of the historic Mediterranean world. It captured the imagination of France not long after it reached there about the fifteenth century, where one intellectual produced a treatise enumerating fifty different ways of eating melons, including in soup, fritters, and served with salt and pepper! The English 'aristocracy' prided themselves on the perfect melons their gardeners produced in their glasshouses. From England and the content, the melon went to America and all the colonies of the 'new world'.
Melons are reasonably priced and seasonably available in countries that span several climatic zones, such as Australia and the USA. While they don't have a very long shelf life, varieties have been bred with reasonably robust rinds to handle long distant transit. The variety and complexity of flavors, sizes, flesh colors and textures makes the melon one of the most exciting and interesting fruits there is. It is also an important source of some nutrients.
High in Potassium, rock melons/canteloupes are an excellent source of vitamin A - they are the second best source (after mangoes) of all the fruit mentioned on this page, with a very respectable 3,224 International Units per 100 grams. In addition, normal serving meets about half an adults daily vitamin C requirements, making them a very good vitamin C source.
Orange Citrus sinensis
Citrus as a genus are not represented in Africa - although there is one obscure, very Citrus like member of the citrus family present, and that is Citropsis daweana. The Mozambique 'Cherry Orange' is a small tree of riverine valleys with citrus smelling leaves, and small, probably edible fruit. So when we radiated to South East Asia, thru Myanmar (Burma) and into Eastern India (the possible place of origin of the sweet orange), we would have been meeting wild citrus not too different from Citropsis, except larger and more edible. The wild ancestral form of the sweet orange hasn't been found. Edibility is fairly widespread in the citrus as a group, with quite a few of the 35 or so species being a potential food item. But the sweet orange is one of the best. The first historical record of the orange is in Chinese writings from 4,400 years ago.
As with most citrus and other good things, the rise of agricultural settlement and both land and sea trading between Europe, the greater Mediterranean through South West and South Asia to China, resulted in the spread of the orange into all these areas. Small citrus groves and protected 'orangeries' of the 'noble' courts were well established in suitable European climates from at least 2,000 years ago. Spanish and Portuguese explorers carried the orange to the 'new world' colonies in the Caribbean Islands and South America in the fifteenth and sixteenth centuries. Late in the eighteenth century citrus culture was already established in Florida, and just introduced into California. The orange was introduced to Australia by the British colonizers in the nineteenth century, and from Australia to New Zealand shortly after.
Today, of course, orange growing is big business, and carried out on a vast scale. This means reasonably priced fruit for the consumer. Oranges travel well, can be cool stored to extend their availability, and some varieties store 'on the tree' in the orchard for quite a while, further extending the season. Most oranges are actually used to make orange juice and other products, with only about 20% of the USA crop, at least, going on the fresh market.
Research into orange growing continues, and one of the more interesting developments, from the nutritional point of view, is the increasing number of 'blood' oranges being grown. These have anthocyanins in the juice, giving a red look to the flesh. Although noone appears to have investigated the matter, it would be reasonable to suspect that they would have increased antioxidant value.
One orange will meet about 20% of an adults daily folate needs, as well as being an excellent source of vitamin C - one orange supplying just over the entire US recommended daily intake (60mg for an adult).
Oranges have natural plant chemicals ('phytochemicals') called 'monoterpenes' in their skin that both protect against cells becoming cancerous, and help fight existing cancers. At least, as studied in laboratory mice - but there is no reason to think these chemicals wouldn't be active in humans. One monoterpene, d-limonene, comprises more than 90% of the oil in orange peel. Unless they are certified as 'organically grown', commercial citrus may have been dipped/sprayed with anti fungal chemicals to prevent storage rots (they may also be dyed to heighten the color, and waxed with a vegetable derived wax to heighten the appearance). Therefore it is advisable to select only organic fruit to chew on the peel. It is unknown if the tumor fighting chemicals survive heat and processing when marmalade is made
Recent tests on the anti-oxidant effectiveness of various commercial fruit put oranges at number five in effectiveness against damaging oxidative processes in cells.
Scientists have recently identified several bioflavonoids from citrus that inhibit certain cytochrome P450 enzymes. One cytochrome enzyme, P450 1B1, can activate cigarette smoke, pesticides and other substances ( 'procarcinogens') in the body to become carcinogens. Hesperetin, the most abundant bioflavonoid in the juice of oranges, has been found to inhibit P450 1B1 from metabolizing procarcinogens, significantly reducing the opportunity for them to be converted into carcinogens.
Papaya Carica papaya
While no members of the genus Carica are present in Africa, there are two species of the closely related genus Cylicomorpha, from central Africa. There is no information on whether or not it has edible fruit.
But Caricas definitely do. There are twenty two species of Papaya, of varying plant and fruit size and edibility. Several more cold hardy species, C. pubescens, C. stipulata and natural hybrids between the two, are used as food in South America. C. stipulata tends to be high in the protein digesting enzyme papain, which can cause irritation to the lips; C. pubescens has tough flesh that only yields to cooking (although the seeds are embedded in a soft sweet pulp). Most are canned in syrup these days. Other species are too small, too dry, too flavorless, have odd tastes, and so on. Only Carica papaya seems to have had the sweetness, flavor, and flesh tenderness to be avidly sought after by the indigenous peoples of South and Central Americas.
The 'tropical papaya' (called by the English and their colonial descendants 'pawpaw') was probably native to the tropical lowlands of eastern Central America. Botanists believe the ancestral fruits were small, probably only 50 or 100 grams or so, and that the present forms are due to millennia of human selection. It spread widely through tropical middle America, from Mexico to Panama. Being easily grown from seed, and having excellent eating qualities, it quickly spread with the Spanish and Portuguese colonizers to the Caribbean, Africa, India, and all places where the climate and soil would allow it to grow.
Papaya are liable to damage in handling, and have only a moderate shelf life. They are reasonably priced in local markets in the tropics, as they grow quickly and easily and produce heavily. Apart from countries with multiple climatic zones, they are otherwise something of a luxury fruit. As a human food, they are of excellent flavor and sweetness, and mix and match with tangy lime juice in a classic combination . And their nutrition value is high.
One serving of papaya will meet about 20% of an adults daily folate needs, and provides about 75% of an adults daily vitamin C needs, an excellent percentage for any food.
Passionfruit, PurplePassiflora edulis
The purple passionfruit is native to an area going from Southern Brazil to Northern Argentina. There are no Passiflora species indigenous to Africa. There are, however, in Asia. I have no information on the edibility or otherwise of the Asian species, but many of the 120 or so species of Passifloras are edible. Some have tiny fruit, some have quite soft leathery skin, one has a rind that can only be opened with a hammer, many are rather small, one, the size of a football, is too big. Even so, there are very nice flavored passionfruit with good handling characteristics, such as P. ligularis, that are never available commercially.
Although passionfruit are - or used to be - prolific fruiting common dooryard fruits in the countries whose climate allows them to grow and fruit, they are quite demanding as to climate and soil conditions. Consequently, the fruit appear on the market more or less as a luxury item.
Purple passionfruits have the third highest potassium level of any domestic fruit on these pages, at 348mg per100 grams.
They have useful amounts of vitamin A, at 700 International Units per 100 grams.
Peach Prunus persica
The ancestral Prunus species which gave rise to both the almond and the peach (they are closely related) was probably native to Central Asia. The peach evolved toward the east of central Asia, toward Western China. The wild peaches of China show enormous variability, with flat fruit, beaked fruit, round fruit, red skin, whites skin, and yellow or white flesh. Our ancestors radiating out of Africa into Central and Western Asia would probably found a much smaller fruit than the one we know today, but it would still be welcome as a summer treat in the hot, dry woodlands of the West Asian interior. Two other species, P. ferganensis of Central Asia and P. mira of West Asia also have edible fruit, but they are inferior to the peach (altho' P. ferganensis has been domesticated in the former USSR).
With agriculture came domestication, and peaches have been cultivated in China for millennia. Almost all peach seedlings produce worthwhile fruit, and they don't take long to come into bearing, so villagers selecting larger or better tasting fruit would soon have improved the fruit. Traders on the silk road took the peach from China to Kashmir and over the central Asian mountains to Iraq (known as Persia in early historic times). When it arrived in Persia and adjacent countries isn't known, but it soon became naturalized there. It is mentioned in Egyptian records about 3,400 years ago, however, so it must have arrived some long time before then. The spread to Europe via South West Asia and the middle East was inevitable. The peach may have been introduced to Greece by Alexander the Great, after his epic wars in Central Asia. The Europeans thought the peach came from Persia, so named this fruit from China 'persica', which means 'Persia'. From Europe, the peach. went to the new world with Spanish and Portuguese explorers and colonizers of the 16th to17th centuries. Interestingly, the Spanish introduced the peach to the Northern Florida/Georgia coast of the USA.
Peaches are a fairly ephemeral fruit of the summer season. They don't keep well, have to be picked at exactly the right stage if they are to ripen 'off the tree' but not bruise in store, and so are worth the price being asked. Firmer fleshed, deep yellow varieties are grown for canning, and these represent excellent value.
One peach ( of around 100 gram size) supplies about 5% of an adults minimum daily Niacin (B3) needs. Fresh and canned peaches have about the same amount of vitamin A, with one medium sized peach having about 530 International Units.
Pear Pyrus communis
Pear species in general abounded in the woods and forests of Central and South West Asia as we came out of the Levantine coastal corridor into the wide, wide world of South West Asia and beyond, so genetically, we are well familiar with this fruit and it's relatives. The ancestral pear, Pyrus communis, grows wild in the forests of parts of Central and South West Asia. The 'European' pears' origin was therefore certainly in this general region, more or less, but it is not an unaltered descendant of P. communis. In the wild P. communis fruits, like most wild pear species, are barely edible - they are small, gritty, hard, astringent and sour. Other species, P. nivalis, the 'snow pear', and P. serotina, the 'Asian pear' are thought to have naturally crossed withP. communis to produce the early forms of the pear we know today. Other species may also have been involved, particularlyP. ussuriensis. It was likely these natural hybrids that our ancestors and bears alike preferred. Of the 22 odd species of Pyrus, only the 'European' (actually 'Central Asian'), the 'Asian' pear and the 'Ussuri' pear (P. ussuriensis) have been domesticated.
The pattern of selection and improvement is linked to sparing preferred trees as the forests were cut to make way for agriculture and herding; spreading of seed of selected trees in human manure; and, very recently, learning how to propagate individual plants by grafting twigs to seedlings grown for the purpose.
Pears from South West Asia spread with settlement and trade into Europe, probably fairly late, as they are not mentioned in the bible. They were highly regarded, both for wine making and as a fresh fruit - altho' even as late as the seventeenth century some writers were claiming raw pears were poisonous! From Europe they went to England, then in the boats of the colonizers to the American eastern seaboard and Australasia.
Today, the people of the North Caucasus mountains still collect wild Pyrus fruit, in spite of having ready access to a range of domestic fruit. And, in an echo from our ancient past, no doubt fathers still show their children where 'the best pear trees are'.
Pears, like their relative the apple, have a good storage life. Unlike an apple, you can't pick up a fully colored, ripe, crisp pear and eat it. Pears have to ripen and soften - not too much, or they are floury. This, and the trees susceptibility to a particular bacterial disease, are the limiting factors in consumer acceptance and grower expansion.
Few fruit can match a perfumed, sweet, juicy and fine fleshed, almost buttery, pear. But this marriage of superior variety and exact point of ripeness is not always easy to find. New pears are being bred, using the 'Asian pear' as a parent. Hopefully, this will produce a fine fleshed, slightly crisp, perfumed and aromatic fruit that will be edible from the moment we select it from the supermarket display. We shall see.
Persimmon, OrientalDiospyros kaki
The genus Diospyros includes quite a few African plants, and a suprising number have reasonably edible fruit. D. lycoides is a small shrub of Central and Southern Africa with small reddish fruit and translucent flesh. The pulp is "faintly sweet and insipid". Unlike D. mespiliformis, whose pulp is very sweet. It's small purple or yellowy fruits are sometimes dried and stored by African tribespeople. D. mespiliformis is common in the gallery forests alongside rivers in Southern Africa. There is increasing evidence that the fruit, fish, and animal resources of such gallery forests constituted one of the major habitats that humans evolved in. D. mespiliformis may, therefore, have been one of our most longstanding dietary items. I have not seen any analysis of this fruit, but another wild Southern African Diospyros. D. dichrophylla, has about 40 mg/100grams of flesh (compare with domestic persimmon fruit, below) Not all wild African Diospyros are small - D. batocana is small apple sized, yellowy orange, with a very acid pulp. The fruit of D. chamaethamnus have already been mentioned. The tropical African D. kirkii has small, sweet mealy fleshed fruit in spring, and is considered by one writer as perhaps being worth domesticating.
Even when a portion of the human species started radiating out of our African homeland, we did not leave 'persimmons' behind. There are wild species from central to East Asia, and also down into South East Asia. One of these, D. roxburghii from the northern part of South East Asia and the southernmost part of Central Asia, was possibly the progenitor of D. kaki.
D. kaki has tannins in the flesh which are responsible for the 'astringency' ( an unpleasant 'furry' feeling in the mouth) of the unripe fruit. Most fruit have a lot of tannins, which do not reduce until the fruit is soft ripe - at which point it absolutely cannot be handled without damage. It is probably for this reason that the fruit was so long to come to the west, apart from it's need for particular climatic conditions and slowness to fruit from seed. And it is also for this reason that people have seized upon any chance seedlings with less tannin in the flesh.
Some plants, such as peaches, are easy to grow from seed, almost always give a good fruit, and take only three or four years to come into bearing. These kind of fruits soon become widespread along the trade routes. Persimmons are the antithesis, which explains, in part, why reduced tannin fruit have been so slow to 'arise'.
It wasn't really until the American and British contact with Japan in the nineteenth century that nurseries in America and Australasia started to obtain varieties of persimmon. They are hard to propagate, the fruit are unfamiliar and difficult to handle, so they had a fairly sparse distribution even then. It is only with the twentieth century identification of types with tannin levels so low they can be eaten when ripe but still firm that the persimmon became a commercial proposition.
And that is where they are today. Persimmons are still climatically demanding, and even in the low tannin fruits, there needs to be a further reduction.
This ancient fruit, whose territory we shared in all the stages of our evolution and radiation, could undoubtedly be improved. Perhaps species from Africa may impart wider adaptation and even lower tannin levels. We will never know; as with all fruits of low commercial 'penetration', there is little effort to radically improve the fruit.
Persimmons are an excellent source of vitamin C, with from 25 to 52mg per 100 grams of flesh, depending on the variety. The most common commercial low tannin variety, 'Fuyu', has 52mg/100 grams. Interestingly, and similar to apples, persimmons have very high concentrations of ascorbic acid in the skin. 'Fuyu' peel, for example, has more than four times the already excellent amount in the flesh.
Lycopene, a carotenoid protective against prostate cancer, is present in some varieties in quite high concentrations, as it is primarily responsible for the bright red color of the skin. How much, if any, is in the flesh, is uncertain. Other varieties have no lycopene at all (the lycopene component of the caretonoids in persimmon fruits varies, depending on the variety, from 0 to 30%). While some very thin skinned home garden varieties can be eaten skin and all, most are peeled before eating. The redder the skin, the higher the lycopene. Commercially, it would be prudent to select 'no spray' or 'organic' fruit if you wanted to eat the skin as well.
Pineapple Ananus communis
- "On the margins of the Campo wild pine-apples also grew in great quantity. The fruit was of the same shape as our cultivated kind, but much small, the size being that of a moderately large apple. We gathered several quite ripe; they were pleasant to the taste, of the true pine-apple flavour, but had an abundance of fully developed seeds, and only a small quantity of eatable pulp"
- Henry Bates, 'The Naturalist on the Amazons', 1879.
This strange and wondrous fruit was taken back to Spain, from whence it was re-distributed to all suitable Spanish colonies, chiefly in the Pacific.
The world's first commercial plantation was set up in Oahu, Hawaii in 1885. Hawaii remained the world's main producer of
pineapples until the 1960's, when production relocated and expanded in the Philippines. Pineapples are produced in all climatically suitable countries, and South East Asia is the dominant producer.
Pineapples keep fairly well, and, because of mass production methods, are relatively cheap.
Most varieties are a good source of vitamin C with a typical serving having around 13mg (about 20% of the recommended daily intake for an adult). Canned pineapple loses about a third of it's vitamin C content in processing, but still contains a useful amount. There is some varietal differences in vitamin C content - 'Queen Victoria' pineapple has about 24mg/100 grams, and the variety 'Del Monte Gold™' has about 53mg/100 grams, making this particular variety an excellent source of vitamin C.
Pineapples contain the enzyme 'bromelain'. Bromelain tablets (extracted from the pineapple plant stems) are sold in health stores with claims they help combat heart disease, arthritis, and various other illnesses . Scientists testing the tablets on the incidence of mammary gland infection in cows (mastitis) found that on average, they reduced the number of white blood cells (a normal immune system response to chronic infection) by a third. How bromelain does it isn't certain, but scientists suspect the enzyme interferes with the synthesis of inflammatory substances in the body, such as prostaglandins.
Plum Prunus sp.
There are two main kinds of plum - the European plum, Prunus domestica, generally oval, mellow and often intriguingly flavored fruit (it also includes the prune plums) and the Japanese plums, P. salicina, the main fresh plums of commerce. There is a third type, P. institia, a native of Western Asia, which includes the small, acid, purple damsons and the small yellow mirabelle plums. Neither of these are of any commercial importance.
The plums our ancestors most likely encountered as some left Africa for Central and then South West Asia was a small plum called the cherry plum or bullace, P. cerasifera, a reasonably edible fruit. Other wild plums in the region included P. spinosa,the sloe plum. This plum is pretty much inedible, being very astringent indeed. Our expansion into China found us amongst the wild P. salicina, the 'Japanese' plum (correctly, obviously, the 'Chinese' plum - it wasn't introduced to Japan until around 400 years ago).
The advances in fruit quality went hand in hand with the rise of agriculture, as it has (but not always) with most fruit. the 'Japanese' plum has probably had the longest human attention; the 'European' plum, P. domestica, is a natural hybrid between the edible P. cerasifera and the largely inedible P. spinosa, and it is suspected to have only occurred in the last 2,000 years or so, probably (but perhaps not only) in the Caucasus Mountain region of South West Asia.
From the South of South West Asia it is a short hop to Mediterranean Europe. Accordingly, Spanish missionaries introduced the European plum to west coast North America, and British colonizers took it to the east coast. Similarly, the European plum was taken to temperate and warm temperate climate colonies within the British Empire.
The 'Japanese' plum was much slower to reach the west, somewhat curiously - although it does need warmer climatic conditions than the European plum. As the name suggests, it wasn't until American and British contact with the previously closed society of Japan in the late nineteenth and early twentieth century that nurserymen in the west acquired plants of this 'novel' fruit.
The Japanese plums and their hybrids are somewhat susceptible to bacterial disease in humid climates, and this has limited their extensive culture to dry climate areas. Plums, along with peaches, are the archetypal 'summer fruit', and the firmer fleshed modern varieties have a good shelf life, store for a while, and handle quite well. Their season is all too short. Plums are good 'fruit of the season', and fresh or dried, a valuable contributor to the human animals diet.
Plums have useful levels of riboflavin (B2), with two (66 gram sized) plums providing about a sixteenth of an adults recommended minimum daily intake, and fairly good amounts of vitamin C.
Dried prune plums ('prunes') were ranked an outstanding first in tests to identify the most antioxidant rich fruits and vegetables. Studies have shown that fresh plums have the fourth highest chemical effectiveness in preventing oxidation in cells of any other commercial fruit. Most of this anti-oxidant activity is in the juicy portion.
Dried plums (prunes), like dried figs, contribute a useful amount of of calcium toward meeting the recommended daily requirement of 800 mgs.
Raspberry Rubus idaeus
There are several species of wild raspberry in our African evolutionary homeland. Rubus ludwigii, from Southern Africa, has small, white pleasant fruit, and R. rigidus, with it's glossy purple-black berries, is common from central Africa to the Cape.
As we radiated out into the fruit and nut filled woodlands of South West Asia, we would have come upon the wild form of the red raspberry, R. idaeus (named after Mt.Ida in the Caucasus Mountains), as well as related wild fruits such as Rubus chamaemorus, R. arcticus, R. saxatilis of the forest tundra belt of North Asia. Raspberries are easy to propagate, as plants or seed. They would have been taken to Europe by traders and soldiers, and the Romans, in particular, played their part in spreading them far afield. The British improved the fruit in the middle ages, and like most fruits, plants were sent to it's colonies, including America (in the late eighteenth century). The red raspberry was already present in America however. A variety of the Southwest Asian raspberry, Rubus idaeus variety strigosus is indigenous to eastern North America. The black raspberryRubus occidentalis, is found only in North America, and it wasn't domesticated until the 1800's.
Raspberries have a very short shelf life, they are liable to damage in transport and handling, and the plant can be subject to quite a few diseases. When conditions are good, they are very productive, and well suited to 'commoditization' as a frozen or pulp product for use in other manufactured 'foods'. Fresh market berries are consequently relatively expensive, and have a short season. Frozen berries may give best value for money.
Laboratory tests suggest some berries may reduce the buildup of LDL (low-density lipoprotein) cholesterol, a contributor to heart disease, stroke and atherosclerosis. Raspberries were tested as having the second highest LDL inhibitory effect. Interestingly, the anthocyanin content (believed to be a protective antioxidant) of raspberries increases in storage, thus increasing their antioxidant value over time.
Strawberry Fragaria ananassa
The forty or so species of strawberry are all more or less edible, and one of the most widespread, F. vesca, the wood strawberry, is found in North Africa. Wherever we roamed in the temperate zone, there were woodland and meadow strawberries to be found. The best of these were F. vesca, F. viridis, and F. moschata (hautbois or musk strawberry). No great improvement seems to have occurred in these species subsequent to the commencement of farming, and while all three species were domesticated to a greater or lesser degree, the strawberry that we know today did not exist.
It wasn't until seeds of a North American species, F. virgininiana (long used by indigenous Indians) were sent to Europe in the sixteenth century that the stage was set for production of the modern strawberry. The 'meadow strawberry', as it was called, was no bigger than the existing cultivated forms of the European woodland strawberry, but had a different flavor and were a different color. Quite a few varieties were selected from this introduction, and they became quite well spread amongst gardens of the day. The Indians of Chile had domesticated another American species, F. chiloensis, and the Spanish, impressed with it's size and eating quality, spread it to other parts of South America, and mentioned it in documents of the day. A Frenchman was stirred to introduce plants to France in 1714. These proved to be fruitless unless cross pollenized by either F. moschata or
F. virgininiana. The natural cross pollenizing eventually resulted in a chance seedling hybrid between chiloensis andvirginiana. This new 'Pine Strawberry' ('pine' as in 'pineapple') was first described in 1759, and was the first ever modern strawberry. And from this beginning breeders have developed the large, firm, red varieties we buy in the shops.
Fruit in general are not good sources of the B vitamin pantothenic acid, with the conspicuous exception of avocados, but strawberries have useful amounts. Half a dozen strawberries will provide almost a third of an adults minimum daily requirement.
Strawberries have very good quantities of vitamin C; five strawberries provide better than half the daily requirement for an adult.
As with tomato consumption, regular strawberry consumption has been significantly associated in one study, at least, with reduced risk of prostate cancer. Strawberries do not contain lycopene (the active carotenoid in tomatoes), so an as yet unidentified natural plant chemical unique to strawberries is responsible for the protective effect.
Strawberries were ranked sixth overall in tests to identify the most antioxidant rich fruits and vegetables. Laboratory tests in another study re-inforce this, suggesting some berries may reduce the buildup of LDL (low-density lipoprotein) cholesterol, a contributor to heart disease, stroke and atherosclerosis. In this last mentioned study, strawberries were tested as having the fifth highest LDL inhibitory effect of all the berries investigated. Interestingly, further studies have shown that strawberries, while having the sixth highest anti-oxidant concentration, are THIRD in actual chemical effectiveness in preventing oxidation in cells. Most of this anti-oxidant activity is in the juicy portion. As with raspberries, the anthocyanin content (believed to be a protective antioxidant) of strawberries increases over time in storage, thus increasing their antioxidant value while on the shelf.
Tamarillo Cyphomandra betaceae
The tamarillo is a short lived small tree grown all along the Andes at 1000 to 3000 Meters altitude. It has been grown for so long by the native peoples that it's natural range and actual place of origin is now unknown. C. betaceae does require relatively frost free, mild conditions, which has limited it's spread. The approximately egg shaped fruit are usually yellow or orange, although the commercially available varieties are usually a red skinned form selected in New Zealand. There are several very closely related species found in the wild, and one, from Bolivia (although present in USDA and New Zealand) Cyphomandra maternum, is suspected to be the distant ancestor of this species. Both the tree and the fruit of C. maternum are almost identical to the tamarillo, except that the ripe fruit from the only C. maternum, population that has been examined so far are so laden with 'hot' chemicals that humans can't eat them. Pigs, interestingly, eat them with aplomb. However, Cyphomandras are distant relatives of tomatoes, and they are quite variable. The tamarillo may once have been as inedible as C. maternum - in fact, some varieties have a very slight hint of the chemicals in C. maternum. Humans have a highly discriminating palate, and have always selected sweeter, more pleasant fruit, and millennia of human preference may well have been responsible for the palatable fruit we have today.
In fact, the first commercial tamarillo varieties lacked sweetness, had a tendency to acidity, and had dark orange flesh and darkest purple seeds pulp. Today, most commercial varieties have red or pinkish red skin, but orange or yellow flesh, orange or yellow seed pulp, and are (usually) sweeter.
Today, tamarillos are produced commercially for export by only a few countries - chiefly New Zealand. There is a small domestic market in New Zealand, Australia, India, and some South American countries. However, no country is actively developing new varieties (unusually for a crop plant, there is also no germplasm collection - anywhere in the world), and it is likely to remain a minor fruit in the supermarket, in spite of it's potential. It is not helped by having relatively poor storage characteristics.
Altho' I have seen no data, it would be reasonable to assume that tamarillos would have a good vitamin A content, and may have the same kind of health beneficial red and yellow plant pigments that tomatoes have. Some writers describe tamarillos as having a 'very good' vitamin C content, which is very likely; however, I have seen no figures. While it is likely to be high in antioxidants - especially the more acid red seeded kinds - it appears not to have been investigated for antioxidant content.
Tangerine/MandarinCitrus reticulata
Citrus as a genus are not represented in Africa - although there is one obscure, very Citrus like member of the citrus family present, and that is Citropsis daweana. The Mozambique 'Cherry Orange' is a small tree with citrus smelling leaves, and small, probably edible fruit that grows in riverine valleys in Mozambique and Zimbabwe. So when we radiated to Myanmar (Burma), South East Asia, and southern China, the possible origin of the mandarin, we would have been meeting wild citrus not too different from Citropsis, except a bit larger and more edible. The wild ancestral form of the mandarin hasn't been found; either that or the mandarin is ancestral to both the orange and mandarins.
Edibility is fairly widespread in the citrus as a group, with quite a few of the 35 or so species being a potential food item. But the mandarin is one of the best. As with most citrus and other good things, the rise of agricultural settlement and both land and sea trading between Europe, the greater Mediterranean through South West and South Asia to China, resulted in the spread of the mandarin into all these areas. In time, the mandarin was spread to Spanish, Portuguese, and- eventually - British colonies. The tangerine was introduced to Australia by the British colonizers in the nineteenth century, and from Australia to New Zealand shortly after.
Mandarins don't travel quite as well as oranges, but they can be cool stored to extend their availability, and the complex hybrids now being produced have better storage and handling characteristics. Hybrids include tangelos (tangerine x grapefruit), tangors (tangerine x orange), and tangtangelos (tangerine x tangelo). Mandarin hybrids, in particular, look set to become a standard market fruit, and excellent nutritional value.
Tangerines are a good source of vitamin A - in fact, they rank number 5 in the list of top sources from commercial fruit, with 920 International Units per 100 grams. They are a very good source of vitamin C - one fruit provides almost half an adults daily requirement.
Tangerines have natural plant chemicals ('phytochemicals') called 'monoterpenes' in their skin that both protect against cells becoming cancerous, and help fight existing cancers. At least, as studied in laboratory mice - but there is no reason to think these chemicals wouldn't be active in humans. Unless they are certified as 'organically grown', commercial citrus may have been dipped/sprayed with anti fungal chemicals to prevent storage rots (they may also be dyed to heighten the color, and waxed with a vegetable derived wax to heighten the appearance). Therefore it is advisable to select only organic fruit to chew on the peel. It is unknown if the tumor fighting chemicals survive heat and processing when marmalade is made.
Watermelon Citrullus lanatus
The watermelon is native to the Kalahari desert of Southern Africa. One form of the fruit is bitter, due to the presence of a glucoside called 'cucurbbitacin'. The other form lacks this bitter chemical, and is the progenitor of all domesticated watermelons. Kalahari tribesmen grind the seed for bread, they dry the flesh, and eat the young fruit as a vegetable. The wild form is quite large, crisp and juicy, but it is also tasteless.
Millennia of association with humans and their agriculture has selected for the sweet fruit we know today.
Watermelon is a very good source of vitamin C, with a typical serving supplying an adult with just on half their daily vitamin C requirement.
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