Indigenous South African Food: Nutrition and Health Benefits

Abstract

Many populations around the world rely on indigenous plant materials as their primary source of nutrition. On the continent of Africa, many rural communities continue to gather, grow, and consume these food crops. In South Africa, there are numerous indigenous food crops, such as cereals, green vegetables, and various kinds of wild fruit. This review discusses the advantages of particular indigenous foods for nutrition and health. Current literature shows that indigenous foods possess vital macronutrients and have positive health benefits. Indigenous crops have the potential to provide options for long-term food security because they have been found to be more resistant to climate change. They might also present opportunities for new products. Literature also indicates that the benefits and value of these traditional foods are still not completely appreciated in South Africa and throughout Africa. The biggest obstacle to achieving these societal benefits is the lack of scientific information about the nutritional content, health benefits, efficient processing, and preserving technology of indigenous food. The potential value of the indigenous food system may be improved if its advantages were more properly investigated.

1. Introduction

Indigenous plants have long been used by humans as food and medicine in practically all communities. They grow naturally in ecosystems and are known to be potent sources of nutrients, therefore better for health. Forager and hunter-gatherer societies historically relied only on local flora for their diets [1]. Currently, to combat food insecurity, many people rely on a varied diet that includes edible plant material harvested from the wild as well as edible plant material grown in backyard gardens. For instance, on the African continent, more than 95% of households use grass, roots, and leaves from wild plants to supplement their diets. To maintain food self-sufficiency and the continued existence of millions of people, these communities cultivate and consume native fruits and vegetables [2]. It has been suggested that indigenous foods can significantly improve diet quality, and food and nutrition security. Despite this claim, the consumption of indigenous foods has decreased as a result of these foods’ unavailability in contemporary industrialized and commercialized markets and a lack of investment in research and development. Consumption, therefore, is associated with poverty and low self-esteem among rural black people [1, 3].

In South Africa, there is a wide variety of locally grown food as well as collected in the wild that is not only nutritious but also effective in preventing chronic illness [4]. Indigenous plant meals have long played a significant role in folklore. Many people in rural areas still harvest and eat both cultivated foods and wild vegetation [2]. There is evidence from studies conducted in South Africa and around the world, that indigenous food is consumed by many households, especially in areas where they are available, and thus can play an important role in alleviating food insecurity and contribute to dietary diversity. These include indigenous grain crops, vegetables, and fruits [1, 2].

Indigenous grain crops produce seeds that are abundant in protein and high in starch. Cereals and pulses are two categories for these crops. Pulses include cowpea and Bambara while cereals include pearl millet and sorghum. Indigenous vegetable crops that can be utilized for food preparation include those with tender leaves, stems, and stalks. These include root/tubers like amadumbe and leafy vegetables such as cleome, cowpea, amaranth, and blackjack. Indigenous fruit crops are fleshy, seed-associated structures that are palatable and delicious when uncooked. These fruits include marula, monkey oranges, and sour figs, as examples [5].

This chapter, therefore, describes these indigenous crops, and their nutritional and health benefits. The diverse indigenous plant foods in South Africa may be exploited to develop ideas and items for many markets, such as new and natural colorants and flavors, medications, and dietary supplements.

2. Indigenous South African food: nutrition and health benefits

Food crops classified as indigenous to South Africa include those that were domesticated there as well as those that were brought in and are now regarded as traditional crops. These crops are grown and produced in a variety of climates, with many of them being found in the wild. Grains, vegetables, and fruit make up the three categories of indigenous crops [5].

3. Indigenous grain crops

Millet was a significant food crop in the distant past in Africa, where it is said to have originated. The introduction of maize was likely one of the main factors in Southern Africa, in which millet’s role was diminished to that of a small cereal crop with limited economic relevance [6]. Recently there has been improvement in the cultivation of millet in South Africa with Limpopo, KwaZulu Natal, and Free state provinces being the major producers [7, 8].

3.1 Pennisetum glaucum (Pearl millet)

Pearl millet (Pennisetum glaucum), a grass of the Poaceae family, is one of the most significant cereal crops grown in the tropics and in developing nations (Figure 1). On about 27 million acres, pearl millet is grown in some of the harsh, tropical areas of sub-Saharan Africa and Asia. It is a crop with numerous applications, such as for food, fuel, and livestock, however, as food, it is primarily used for thin and thick porridge. Smallholder farmers in Southern Africa have grown Pearl millet largely for subsistence, but its uses have expanded over time [10].

Figure 1.

Pearl millet crop (A) and grains (B) [9].

Pearl millet grains are beneficial due to their high fiber, fatty acid, and phytochemical content. It has a high mineral content, 70% carbohydrate content, 9–13% protein, 5–7% lipids, 70–74% polyunsaturated fatty acid, and high mineral content (Fe, Zn, Ca, Mg and P) [11]. Pearl millet’s anti-inflammatory, antihypertensive, anticarcinogenic, and antioxidant qualities assist prevent heart disease, inflammatory bowel disease, and atherosclerosis. Pearl millet grains are naturally gluten-free, which is beneficial because wheat’s gluten protein has been related to metabolic disorders such as intestinal permeability, allergies, intolerances, and autoimmune diseases. Pearl millet may be a low-cost alternative for celiacs, people with non-celiac gluten sensitivity (NCGS), and gluten-sensitive people [12]. As a source of soluble and insoluble fiber, it increases insulin sensitivity, reducing the risk of type II diabetes [11]. Pearl millet’s anti-nutritional components (phytate, tannins, and oxalic acid) restrict its use [13]. Therefore, anti-nutrients must be removed. Decortication, heating, soaking, germination, and fermentation may reduce antinutrient levels [14].

3.2 Sorghum bicolor L. (Sorghum)

Sorghum (Sorghum bicolor, L.), (Figure 2), which was initially cultivated in Northeast Africa more than 60 centuries ago, is a drought-tolerant and climate-resistant crop. Most of the world’s sorghum is grown in Africa (39.2%), the Americas (38.2%), and Asia (18.3%) [16]. Sorghum is a crop of the Gramineae family that is high in carbohydrates. It was domesticated between 3000 and 5000 years ago, and today, after wheat, maize, rice, and barley, it is thought to be the fifth most significant carbohydrate-rich crop in the world. Sorghum plays a key role in the fight against hunger and food insecurity [17].

Figure 2.

Sorghum crop (A) and grain (B) [15].

Sorghum is traditionally prepared by boiling, roasting, baking, and deep-frying. Unfermented or fermented sorghum grains can form sorghum porridge (typically combined with other grains like maize and millet). It is also used to make alcohol [18]. Sorghum contains slowly digesting starch, low-digestibility proteins (kafirins), and unsaturated fatty acids. It has phosphorus, potassium, zinc, and B-complex vitamins thiamine, riboflavin, and pyridoxine (D, E, and K). Red, dark, and black cultivars include 3-deoxy anthocyanidins and tannins [17]. Sorghum is now used in breakfast cereals, infant formula, confectionery, and gluten-free baking. The restricted usage of sorghum in the food sector is partly due to challenges in processing sorghum endosperm, where significant protein cross-linking of hydrophobic kafirins hinders starch functioning during hydrothermal cooking. Sorghum is unique among main cereal grains since it possesses significant quantities of bioactive components that can enhance human health. Polyphenols, notable flavonoids, are sorghum’s most useful bioactive components. Sorghum is abundant in bioactive lipids (particularly policosanols and phytosterols) in the grain pericarp waxes. Sorghum endosperm has a slower starch digesting profile than other cereal grains, which modulates postprandial blood glucose response. Research on sorghum’s ability to reduce chronic diseases has focused on polyphenols and endosperm digestion. Some types of cancer can be prevented, glucose metabolism is enhanced, insulin resistance is lowered, lipid metabolism is improved, fat storage is repressed, and gut flora is modified to promote colon health, as examples of positive impacts [19]. In vitro studies demonstrate that sorghum compounds, especially 3-deoxy anthocyanidins, tannins, and lipids, modulate noncommunicable disease and gut microbiota functions (obesity, diabetes, dyslipidemia, cardiovascular disease, cancer, and hypertension). Understanding sorghum’s bioactive compounds that support these benefits is crucial [17].

3.3 Vigna unguiculate (Cowpea)

Cowpea (Vigna unguiculata L. Walp), is an indigenous African legume crop, having originated in Africa and spread throughout Latin America and Southeast Asia [20] Cowpeas often grow as climbing or trailing vines with three-lobed compound leaves. At the ends of long stalks, the white, purple, or pale-yellow flowers typically appear in pairs or clusters of three as in Figure 3. Depending on the cultivar, the pods can reach a length of 20–30 cm (8–12 inches) and are long and cylindrical [22].

Figure 3.

Cowpea leaves and pods [21].

Cowpea is a member of the Fabaceae family, subtribe Phaeseolinae, Vigna genus, and Catjang section. The V. unguiculata subspecies unguiculata is responsible for all cultivated cowpeas (Figure 4). The black-eyed pea, black-eyed bean, Crowder pea, Southern pea, frijol caup, and feijo-caup are all names for this legume crop [24]. The cowpea plant is predominantly cultivated for its grain (dry or fresh) and leaves. Cowpea seed flour is versatile and important for making several dishes and snacks. For example, cowpea seeds can be consumed raw, cooked, parched, fried, roasted, combined with the sauce, or stewed. Cowpeas are full of nutrients that are good for health, including fiber, plant-based proteins, vitamins (A, C, thiamine, riboflavin, folate, and B6), iron, selenium, zinc, magnesium, phosphorus, and copper. Black-eyed peas’ high fiber content and plant-based proteins lower hunger hormones and facilitate weight loss [23]. However, cowpea possesses a lot of antinutrients such as phytic acid and protease inhibitors. Numerous treatment techniques, such as soaking, germination, fermentation, or debranning, can be beneficial to increase the availability of nutrients in cowpeas and reduce their antinutrient characteristics.

Figure 4.

Six seed coat color patterns in cowpea: (A) Black color; (B) Blackeye color (C) Browneye color; (D) Cream color; (E) Pinkeye color; and (F) Red color [23].

Cowpeas improve heart health, blood circulation, and cholesterol levels. Cowpeas’ low glycaemic index reduces blood sugar spikes. As a result, adding them to the diet is good for diabetics. Cowpeas boost collagen synthesis, which improves brightness, reduces wrinkles and restores skin. Black-eyed peas are rich in folate, which is helpful for pregnant women and fetal growth [25]. Cowpea leaves and green pods are used traditionally to cure measles, smallpox, adenitis, burns, and ulcers. Cowpea seeds are astringent, antipyretic, and diuretic. The decoction is useful for liver and spleen difficulties, intestinal pains, leucorrhoea, monthly abnormalities, and urine expulsions. Cowpea flatulence hinders its consumption. The presence of raffinose, a stomach-upsetting fiber, may induce abdominal pain, gas, and bloating in some persons. Soaking or fermenting cowpeas before cooking reduces flatulence and improves nutrient absorption [26].

3.4 Vigna subterranean (Bambara groundnut)

The Bambara groundnut (Vigna subterranea L. Verdc.; Syn: Voandzeia subterranean L. Thouars.) is an indigenous, underutilized legume species widely produced in drier areas of sub-Saharan Africa, including South Africa [27]. It is considered the third most common major legume after groundnuts (Arachis hypogea) and cowpeas (Vigna unguiculata) on the African continent. South Africans grow Bambara groundnuts for subsistence. It is an annual plant with creeping, low-growing branches (Figure 5A). It takes three to six months to mature, depending on the variety and weather. After pollination, pods grow underground. Unripe pods are yellowish-green and have up to six pods, whereas mature pods may be purple (Figure 5B). The 1–5 cm long pod is spherical or oval. It sometimes has two seeds. Mature pods are indehiscent and yellow to reddish-dark brown [29]. Its dried seed can be eaten like any other dry vegetable or used to make soy-like vegetable milk. The seeds are eaten alone or with maize. Bambara nut is a nutrient-rich legume considered a “balanced diet.” Dried Bambara seeds contain 64.4% carbohydrates, 23.6% protein, 6.5% fat, and 5.5% fiber and are rich in micronutrients such as potassium (11.44–19.35 mg/100 g), iron (4.9–48 mg/100 g), sodium (2.9–12.0 mg/100 g), and calcium (95.8–99 mg/100 g) [30].

Figure 5.

Bambara groundnut mature plant (A) and pods (B), [28].

Bambara groundnut also has different physical and medicinal benefits; for example, the water from steamed seeds of Bambara groundnut is used to remedy diarrhea. Bambara groundnut diets may contain nutraceuticals that protect against high blood pressure and oxidative stress. The sap from Bambara groundnut leaves can be administered to the eyes to cure epilepsy. South African pregnant women consume raw seeds to manage nausea and vomiting [31]. Flavonoids and tannins are found in Bambara groundnut seeds, according to Tan et al. [32] and these compounds are common in dark or crimson seed coatings. Total phenolics and seed coat darkness are correlated. Despite the favorable health effects linked to the ingestion of Bambara groundnut, their antinutritional effects should not be disregarded.

4. Traditional leafy vegetables

Leafy vegetables include succulent young stems, blossoms, and fruits. Traditional African groups eat green vegetables as a traditional practice. Green leaves of indigenous plants are consumed fresh or cooked and eaten with porridge as a relish (spinach, morogo, imfino) [33]. Amaranthus, Cleome, Corchorus, and Vigna leaves can be short-boiled, sun-dried, and kept for further use or trading. Most of the green vegetables consumed by rural South Africans are weeds or wild plants. Local sourcing limits availability, quantity, and time. In South Africa’s rural areas, more species could be cultivated, but little is known about their agronomic needs [34].

4.1 Amaranthus

The family Amaranthaceae, which has around 70 distinct species, includes the genus Amaranthus. Amaranth species, such as A. doubtful L., A. hybridus, and A. tricolor L., are often found in Asia and Africa and are used as leafy vegetables [35]. In South Africa, various amaranth species are used. Some are native, while others are weeds that have spread naturally from Europe and the Americas. One of the most popular leafy vegetable species is A. hybridus L (Figure 6) [5]. The young leaves, growth tips, and whole seedlings are gathered from fallow pastures and fields. Amaranth is harvested, prepared, and served as a side dish to corn porridge. Since amaranth is believed to naturally grow there, along with many other traditional leafy vegetables, it is rarely planted in South Africa. However, in the Bushbuckridge region of the provinces of Limpopo and Mpumalanga in South Africa, women do collect and store seed, which is then disseminated on their field when a decline in the natural population is noted. Another technique used to replenish natural seed stores is selective weeding, which protects amaranth and other traditional green crops growing in cultivated fields [36].

Figure 6.

Amaranthus hybridus plant [5].

Amaranthus contains considerable amounts of dietary minerals, vitamins, proteins, and bioactive substances that may be beneficial to health [35]. It has historically been used as an analgesic, to induce labor, as an antipyretic, laxative, diuretic, digestible, anti-diabetic, anti-snake venom, and as a therapy for jaundice. Its immune-modulating, anti-inflammatory, antibacterial, and antioxidant antimalarial effects have all been documented [37].

4.2 Bidens pilosa (black jack)

Bidens is a flowering plant genus with over 230 species belonging to the Asteraceae family. It is commonly called by numerous names such as hairy beggar tick; Spanish needles; devil needles; blackjack [38]. This genus is distinguished by the number of thorny bristles that stick onto animal coats or human garments. The number of thorns ranges from two to four; some species possess lengthy ray flowers and serrated segments, while others have undivided lance-shaped leaves with short ray flowers or none at all, while the majority have yellow disk flowers (Figure 7). Bidens pilosa is also used as a traditional leafy vegetable and to improve human health. The young shoot tips are used in tea and juice. The potential of Biden Pilosa for food and as a source of supplement is supported by its nutritional content, which includes calcium, phosphorus, percentage moisture, energy, and carotene [40, 41].

Figure 7.

Bidens pilosa, A: flowers, B: Leaves C: Fruit [39].

All parts of B. pilosa plant have been employed globally in traditional medicine to treat a variety of diseases, with specific indications differing from nation to nation. Bidens pilosa is a significant traditional medicine in South Africa that has been utilized for a variety of treatments by numerous cultural groups. For example, a leaf decoction is used to treat flatulence, ear infections, headaches, and renal issues. Additionally, the whole plant is employed as a poison antidote, and the leaf extract is utilized to treat malaria, stomach and mouth ulcers, diarrhea, hangovers, and hangovers [38, 42]. There are several main chemical compounds (about 300 constituents) belonging to phytosterols, fatty acids, pheophytins, terpenes, phenolic acids, okanin glycosides, chalcones, aurones, flavone glycosides, flavonoids, polyacetylene glycosides, and polyacetylenes identified and isolated from different parts of blackjack plant. The plant’s therapeutic effects appear to be attributed to its bioactive phytochemical components, particularly sesquiterpene lactones and polyacetylenes, which inhibit the growth of pathogenic microorganisms, and flavonoids, which are recognized as effective anti-inflammatory agents. It has been discovered that the phytochemicals and essential oil of Bidens pilosa contain amounts of phenolic compounds that can scavenge or neutralize free radicals [42]. Despite its usefulness, B. pilosa’s application is hindered by its categorization as inversive species [41].

4.3 Cleome gynandra (Spider plant)

The Cleome, a member of the Cleomaceae family is indigenous to South Africa. The tender leaves or young branches, and frequently the flowers (Figure 8), are boiled and eaten as a potherb, pleasant condiment, stew, or side dish throughout Africa. Other mashed foods incorporate fresh leaves as an ingredient while weaning foods contain dried leaves that have been ground and added. Due to Cleome’s bitterness, other green vegetables including cowpea (Vigna spp.), amaranth (Amaranthus spp.), and blackjack (B. pilosa) are often cooked with these leaves. Cleome is a good source of nutrients, including minerals (calcium and Iron) and vitamins (A and C). Leaves can be ground up and used to make a medicine that is taken internally to treat conditions like scurvy. In some cultures, leaves are prepared as a healthful meal that is believed to improve vision, provide energy, and alleviate marasmus. They are then boiled and marinated in sour milk for two to three days. It is a dish that pregnant and nursing moms are strongly warned against eating [44].

Figure 8.

Traditional leafy vegetable, Cleome gynandra, growing at Genoa village in the Limpopo Province, South Africa. (A) Whole plant; (B) leaves; (C) flowers [43].

Cleome is highly regarded for its varied medicinal benefits against a number of ailments and conditions in addition to its nutritious composition and features. The majority of a plant’s parts, including the leaves, are utilized to treat a variety of illnesses. In several nations, a decoction of Cleome gynandra leaves is used to treat malaria. Many pain-related diseases, including headache, neuralgia, stomachache, earache, rheumatoid arthritis, skeletal fractures, colic discomfort, and chest pain, are treated using the leaves and blossoms of Cleome gynandra. Cleome gynandra may contain anti-inflammatory phytochemicals that help reduce both acute and chronic inflammation, according to research on the treatment of pain-related illnesses. The idea that leaves contains a range of antibacterial chemicals is supported by their usage in the treatment and management of wounds, abscesses, diarrhea, and chancroid [45].

4.4 Corchorus olitorius (Wild orkra)

Corchorus olitorius, often known as wild okra or jute mallow, is a member of the Tiliceae family. It is a tropical, fast-growing, annual herb, up to 4 m tall, with a fibrous stem and yellow flowers in 1 to 2 months from the time of germination (Figure 9).

Figure 9.

Images of Corchorus olitorius in different habitats [46].

Corchorus olitorius is one of the most commonly consumed traditional African vegetables. It is obtained from both farmed and wild sources and is rich in vitamins, mineral salts, and folic acid, making it an essential dietary component. The leaves are consumed as part of vegetable-based side dishes served with starchy foods. It can be prepared alone, in combination with legume leaves or other wild vegetables, or with fish sauce. Therefore, it could play a crucial role in Africa’s food security and fight against poverty [47]. Corchorus olitorius grows in the wild in KwaZulu Natal, Mpumalanga, Limpopo, and Gauteng, South Africa. It is primarily consumed in Limpopo, where it is gathered from the wild and eaten either fresh or dried. It is known to have high concentrations of iron and folate, which are beneficial for preventing anemia. In folk medicine, wild okra is used to cure gonorrhea, chronic cystitis, pain, fever, and tumors [48].

4.5 Colocasia esculenta (L) Schott (Amadumbe)

Colocasia esculenta (L.) Schott; also known as taro is an annual herbaceous plant from tropical and subtropical climates and a member of the Araceae superfamily [49]. Colocasia esculenta is a tall herb that blooms and bears leaves simultaneously (Figure 10). It may be tuberous or have a thick, short caudex. Stem above ground zero, or slightly inflated at the base of the leaf sheaths, emerging from a firm, tapering rhizome, or, in cultivated varieties, a tuberous rhizome, with occasionally present suckers and stolons [51].

Figure 10.

Colocasia esculenta plant (a), leaves (b), and corm (c) [50].

Important nutrients include carbohydrates, protein, thiamine, riboflavin, niacin, oxalic acid, calcium oxalate, minerals, lipids, unsaturated fatty acids, and anthocyanins present in the corms of this plant. When compared to potatoes, sweet potatoes, cassava, and rice, taro is more nutritious. The simple digestion of its starch granules and its nonallergenic characteristics are other factors that make taro a valuable food plant. Taro has also historically been utilized as a medicinal herb for therapeutic purposes. Traditionally the corm of taro is used as a remedy for body aches. The juice extracted from corm is used in alopecia, as an expectorant, stimulant, appetizer, and astringent. All plant components of this species can be used to extract a wide range of bioactive chemicals [49].

In terms of amount and variety, the edible part of taro is a rich source of antioxidants, primarily phenolic chemicals. Taro phytochemicals exhibit antimicrobial, immunomodulatory, antioxidant, anticancer, antimetastatic, antimutagenic, anti-hyperglycemic, and anti-hypercholesterolemic bioactivities in addition to their antioxidant properties. The use of taro, a potential alternative staple food with a lower glycemic index than potatoes, may reduce the incidence and prevalence of a number of diseases [52, 53].

5. Indigenous fruits

The majority of indigenous fruits are still picked from wild trees in many areas of Southern Africa. Previous research demonstrated that indigenous fruits and their by-products are abundant in phytochemicals with antibacterial and antioxidant activities, such as phenolic acids, flavonoids, triterpenes, and lignans. Phytochemical extracts from native fruits have been used as treatments for various illnesses, including sinusitis, fever, asthma, diarrhea, indigestion, and skin conditions [54].

5.1 Sclerocarya birrea (Marula)

Sclerocarya birrea (A. Rich.) Hochst, more commonly known as marula, is taxonomically derived from the Anacardiaceae plant family [55]. It is an indigenous, fruit-bearing tree of sub-Saharan Africa. Significant attention has been paid to the domestication and commercialization of Sclerocarya birrea. The fruits have stiff skin that ripens to a pale-yellow color and are plum-sized (3–4 cm in diameter) (Figure 11). Its flesh has a fibrous, mucilaginous texture, is extremely fragrant, and tastes juicy, sweet, and sour. The fruit’s interior is a firm nut with 1–4 locules that encloses a soft, white seed that is rich in oil [54].

Figure 11.

Marula fruit [56].

Traditionally, marula has multiple uses. Fruit pulp is widely consumed by humans as well as animals. Apart from raw consumption, the fruit pulp is used to make a variety of juices, jams, jellies, and liquor (Amarula) which are sold in national and international markets. The fruit pulp has been reported to contain high levels of vitamin C (54–194 mg/100 g). In addition, minerals such as calcium, iron, and zinc have been reported to occur in fruit pulp.

The seed kernel is an important source of edible oil. Monounsaturated fatty acids and natural antioxidants are abundant in marula oil. It can be categorized as having a high oleic acid content (70–78%) and a low tocopherol level. Therefore, it has been hypothesized that its fatty acid makeup accounts for its extraordinary stability. Recent research has suggested that a few of the oil’s minor ingredients might potentially be contributing to this vital antioxidant function. Olive oil and marula oil both have similar fatty acid compositions, however, marula oil is 10 times more resistant to oxidation [57].

In addition, the seed kernel is used as a substitute for groundnuts in cooked vegetables, especially in South Africa. Other nutritional components such as fiber and carbohydrates have also been reported in S. birrea seed kernel. Various parts of S. birrea tree such as the root, leaves, bark, and seed kernel have, for a long time, been used for medicinal purposes. Extracts from the tree parts have acted as traditional remedies for treating diarrhea, headache, toothache, stomachache, swollen legs, anemia, malaria, high blood pressure, and scurvy. Several scientific examinations have also confirmed the availability of phytochemicals such as alkaloids, saponins, terpenoids, and tannins from the extracts of S. birrea tree parts. Thus, apart from consumption, fruit is also heavily exploited in the pharmaceutical industry [58].

5.2 Strychnos spinosa (Monkey orange)

The indigenous fruit tree S. spinosa has more than 30 aliases. The plant belongs to the Loganiaceae family, which contains more than 200 species in its largest genus. One of the common names for this fruit, “Spiny Monkey Orange,” refers to the tree’s spines and the fact that monkeys eat and seek out this fruit in great quantities [45].

The tree bears edible fruits which have a bright green wood peel (3–4 mm thick), which turns yellow–brown upon ripening (Figure 12). The fruit has an edible, juicy, sweet–sour pulp, which is pale brown in color and contains many hard brown (1–3 cm) seeds.

Figure 12.

Strychnos spinosa fruit- Unripe fruit (a), Mature fruit (b), Ripe edible fruit (c) [59].

Strychnos spinosa trees provide tasty, high-nutrient fruits. The fruit is rich in carbohydrates, protein, lipids, fiber, and minerals. Monkey orange pulp contains 0.46 mg/100 g Cu, 0.23 mg/100 g thiamin, and 1.39 mg/100 g nicotinic acid [58]. Monkey orange pulp’s sweet–sour flavor boosts consumer acceptance. The fruit includes 4 g/100 g of fiber, 70–140 mg of iron, and 34 mg of vitamin C. Micronutrients are important for development, bone formation, enzyme activity, and energy metabolism [60]. Fruits produce sweet juice, pulps, purees, and nectars, depending on the extraction process. Strychnos spinosa is KwaZulu-most Natal’s (one of the provinces in South Africa) important indigenous fruit tree. Traditional production of fruit juice from S. spinosa species and enhanced technologies could benefit cooperatives and small-scale processors by broadening what they sell. The plant is used in traditional medicine to cure STDs, skin illnesses, snakebites, hypertension, malaria, pain, and inflammation. Different ethnic groups may use different plant components, preparations, and administrations to treat these conditions [61] More than 25 compounds have been profiled using gas chromatography–mass spectrometry (GC–MS), while about 45 compounds have been extracted and structurally characterized using UV–visible, Infrared (IR), Nuclear Magnetic Resonance (NMR), and mass spectrometry (MS). Strychnos spinosa has biological action against microorganisms (bacteria and fungi) and parasites (plasmodia, trypanosomes, and ticks) that cause human and animal sickness [45].

5.3 Carpobrotus edulis (Hottentot-Fig)

Carpobrotus edulis L. (syn. Mesembryanthemum edule L., Aizoaceae), globally recognized as an aggressive invasive species of coastal environments is a medicinal and edible succulent extremophile plant native to the coast of South Africa. Various common names for it include sour fig, Cape fig, and Hottentots fig. In South Africa, Carpobrotus edulis has a long history of use in both traditional medicine and food [62].

The fruit produced are yellow, fleshy, spin-top-shaped fruits that turn reddish-brown, wrinkled, and leathery as they develop (Figure 13) [54]. Fresh, boiled, or dried C. edulis fruit can be used in pickles or chutney. C. acinaciformis and C. delicious have sweeter fruits, whereas C. edulis is astringent, salty, and sour. Carpobrotus edulis has been found to have high quantities of moisture (77.6–90.3%), carbohydrate (58.8–70.3%), energy (1240–1370 kJ 100 g1), and protein (8.1–26.0%). This data shows that Carpobrotus species could contribute to human nutritional needs as a dietary supplement since they contain a higher variety of important components than most commercially farmed fruits [64]. Leaf juice is used to cure diarrhea, TB, sore throats, gum infections, and burns. Eastern Cape traditional healers use it to treat intestinal worms, constipation, high blood pressure, and diabetes [62, 65, 66]. Fruit extracts alleviate skin and respiratory diseases, hypertension, and diabetes [54].

Figure 13.

Hottentont fig plant (A) and fruits (B) [63].

6. Conclusion

Indigenous foods provide nutritional and therapeutic benefits. Most of these crops are undervalued because they are considered weeds or poor man’s food, lowering their economic position. Indigenous foods are gaining popularity due to the need to promote food security and provide alternate diets for those with diseases such as Type II diabetes. These meals’ nutritional components and bioactive substances are determined using advanced techniques. Some of these foods, like cowpea, have been shown to have significant nutrition content but are limited by antinutritional factors. More research and funding should be dedicated to indigenous crop research to optimize their use.

Acknowledgments

The author acknowledges the Vaal University of Technology for the financial support.

Conflict of interest

The author declares no conflict of interest.