1 Introduction

People have different reasons for the consumption of specific groups of fruit; however, the main traditional aim for consumption is the potential supply of energy and nutrients [1]. Production of highly nutritional-dense crops is required to meet the world’s growing nutritional demand in the twenty-first century. Producers of conventional crops such as grains, vegetable and fruits face intense pressure to grow crops in the best conditions due to the ongoing demand for high-quality food from both developed and develo** nations. An ongoing quest for “new” crops that may be added to the food supply and/or are commercially viable is essential to addressing the world’s food and medicinal shortages [2,3,4]. This highlights the need to introduce alternative crops that perform well under adverse conditions in order to meet the nutritional and medical demand, globally. In recent years, studies on climate change adaptation have focused notably on the production and use of underutilized food crops, including wild edible fruit species [5]. As a result, the sustainable development goals (SDG) have garnered more study interest towards eradication of hunger under slogan (Zero hunger). Wild edible fruit crops, according to [1, 6] are those that grow naturally without regular access to agricultural inputs like irrigation and fertilizer. The Olacaceae family of flowering plants in Sub-Saharan Africa has **menia caffra (X. caffra) commonly known as Wild sour plum, which is one of the several examples of underutilized wild fruit trees that can be consumed and, it grows naturally throughout Sub-Saharan Africa [7,8,9,10]. The tree can sometimes be found in grasslands and woodlands, as well as on rocky outcrops. In South Africa, the tree is commonly found in Kwazulu Natal and Limpopo Province [11, 12]. In terms of utilisation, different authors reported that ripe fruit is abundant in potassium, protein, and vitamin C [13]. The oil content of the seed is range between 50 and 65% [14, 15]. Fruits are finest consumed when slightly overripe, but they can also be used to make value-added products such as jam, desserts, jellies and it can be included in porridge. Regarding medicinal use, to calm red, irritated eyes, a decoction of the leaves is used as a wash. Infusions of the roots and leaves are taken for abdominal pain, bilharziasis, and dysentery [16, 17]. The roots are also used as a treatment for diarrhoea and dysentery [13]. Roots that have been grounded up are used in soup, as an aphrodisiac in beer, and as a treatment for sores to hasten healing [13]. Dried leaf powders are given orally for fever and sterility, while leaf extracts are gargled for tonsillitis and used as a vermifuge [18]. In order to treat morning sickness during pregnancy, the roots are decocted and used to make porridge. Moreover, the root decoction is also used to treat infertility [15]. The plant can be propagated from fresh seed on substrates with good drainage, aeration and a moderate water retention capacity [19]. Under favourable conditions, the seeds begin to sprout after 14–30 days. When planted in the ground where it can come into contact with the roots of other plants, the plant thrives [10]. It can endure light cold and drought, and it grows at a moderate rate height of up to 0.5 m per year. However, it requires full sun [20]. This review investigated the biochemical components of X. caffra and its significance in human health and nutrition, for prospective commercialization.

2 Materials and methods

Between January and May 2023, the following databases were used to search online literature: Scopus, Web of Science, Google Scholar, and ScienceDirect. Key phrases utilized included: **menia caffra, biochemical components, the importance of fruits to human health and nutrition, and African native fruits that are underutilized yet have commercial potential. Authors selected literature between 1990 and 2023, to include in this review. Only 59 of the 150 articles that were found through the search engines were used in this review. Selection criteria included how well each item related to the review paper, and the document arrangement was determined by its usefulness of sections taken into consideration from the literature. The following research questions were developed to aid authors in writing the review article; (i) What is known about the biochemical composition of X. caffra in the literature? (ii) How is X. caffra used in food and medicine? and (iii) What are the nutritional advantages of X. caffra plant material and their role in human health and nutrition?

2.1 Botanical, physical attributes and habitat of X. caffra

** fruit tree portfolios that link agriculture more effectively with nutrition and health: a new approach for providing year-round micronutrients to smallholder farmers. Food Secur. 2019;11:1355–72. https://doi.org/10.1007/s12571-019-00970-7 ." href="/article/10.1007/s42452-024-05639-1#ref-CR2" id="ref-link-section-d93104120e594">2]. The seeds contain a significant amount of oil according to [13]. Fruits can be used to make jam, dessert, and jelly, in addition to being best consumed when slightly overripe [12]. According [12], nuts are also consumed, and the oil from the seed is used to soften human skins.

2.3 Utilisation of X. caffra plant material

** fruit tree portfolios that link agriculture more effectively with nutrition and health: a new approach for providing year-round micronutrients to smallholder farmers. Food Secur. 2019;11:1355–72. https://doi.org/10.1007/s12571-019-00970-7 ." href="/article/10.1007/s42452-024-05639-1#ref-CR2" id="ref-link-section-d93104120e755">2]. The calcium content variation between X. caffra (23.2 mg) as reported by [2] in (Table 1), as compared to recommended daily intake (1000 mg) was (977 mg). This could mean X. caffra has the potential contribute about (2.3%) of calcium recommended per day by humans. Even though the X. caffra calcium content is lower when compared to the recommended daily intake (RDI), the value reported shows that X. caffra has a potential to curb various diseases such as poor bone development and dental problems, which are inked to calcium deficiency in human diet.

Table 1 Macro-mineral content of X. caffra fruit
Full size table

2.5 Phosphorus

All human tissues and cells require phosphorus for growth, maintenance, and repair, as well as for the creation of the genetic building blocks, DNA and RNA [33]. Vitamin D and various minerals such as iodine, magnesium, and zinc, require phosphorus in order to be balanced and used [33]. The variation between X. caffra phosphorus content (128 mg) as quantified by [2] in (Table 1) and recommended daily intake (3000) was (2872 mg), which is (4.3%) of recommended daily intake. The phosphorus value reported by [2] could mean that X. caffra has a potential role in prevention of health-related challenges such as loss of appetite, bone pain and stiff join, which are symptoms linked with phosphorus deficiency in human diet.

2.6 Magnesium

The mineral is crucial for hel** more than 300 enzymes carry out numerous chemical processes in the body, including those that produce proteins, and nerve function [1]. In addition, magnesium is necessary for a variety of bodily functions, including controlling blood pressure, blood sugar levels, and muscle and neuron function [1]. Authors such as [15] reported the role of magnesium as being a crucial role player in maintaining healthy body temperature, releasing stored energy from muscles, and synthesising proteins [15]. The variation between the magnesium content of X. caffra (17.5 mg) as reported by [15] in (Table 1), compared to recommended daily intake (370 mg) is (353 mg), which is about (4.7%) of recommended daily intake. Even though the magnesium content of X. caffra is lower, values reported could mean that consumption of X. caffra has potential to prevent diseases such as irregular heartbeat, nausea and diarrhoea, which are linked to magnesium deficiency in human in human diet.

2.7 Sodium

According to [1], the human body need sodium in order to conduct nerve impulses, muscle relaxation and maintaining the right ratio of water and minerals. For these essential processes, it is estimated that human body require at least 500 mg of sodium every day [15]. The variation between sodium content (3.4 mg) of X. caffra as reported by [1]. The variation between potassium content of X. caffra (671.7 mg) as reported by [37] in (Table 1), when compared to recommended daily intake (1800 mg) was (1224 mg), which was about (55%) of recommended daily intake. This could mean that the X. caffra has potential to decrease human health risks such as cardiovascular disease, which are symptom diseases linked with potassium deficiency in human diet.

2.9 Copper

The mineral copper is present in every part of the body [1]. It keeps nerve cells and immune system healthy, therefore aids in the production of red blood cells in human body [38]. Collagen, a crucial component of bones and connective tissue, is also formed with the aid of this substance [36]. The idea that minor deficiencies of this crucial mineral may play a role in the onset and progression of several disease such as diabetes and cardiovascular disease, has gained more attention in the twenty-first century [34]. This micro mineral can be deficient during pregnancy, which can cause severe morphological defects in the foetus, long-lasting neurological and immune problems [33]. The variation between X. caffra copper content (0.23 mg), as reported by [2, 2] in (Table 3), when compared to recommended daily intake (83 mg) is (275 mg). High Vitamin C content of X. caffra could mean that the fruit may play a pivotal role in curbing health complications such as anaemia, bruising gums, dry skin and poor hair growth, which are associated with Vitamin C deficiency in human diet.

2.18 Medicinal values and bioactive compounds of X. caffra

** fruit tree portfolios that link agriculture more effectively with nutrition and health: a new approach for providing year-round micronutrients to smallholder farmers. Food Secur. 2019;11:1355–72. https://doi.org/10.1007/s12571-019-00970-7 ." href="/article/10.1007/s42452-024-05639-1#ref-CR2" id="ref-link-section-d93104120e2083">2]. These bioactive compounds have potential applications in the food, pharmaceutical, and cosmetic industries.

2.20 Alcohol products

The fruit of X. caffra holds potential for the production of alcohol products according to [13]. Fermentation of the fruit pulp can yield alcoholic beverages with unique flavours and aromas. Further research should focus on effectively fermenting X. caffra fruit pulp to produce wines and spirits [12]. The development of alcoholic beverages from X. caffra will not only offers a novel addition to the beverage industry but also provides opportunities for the utilization of the fruit’s abundant resources.

2.21 Oil

The seed inside X. caffra fruit is a rich source of oil, which has garnered interest for its potential applications [2.24 Medicine

** natural medicines and pharmaceuticals targeting various diseases and disorders. The traditional use of X. caffra in African folk medicine provides a valuable starting point for investigating its medicinal potential.

**menia caffra metabolite profile, including its oils, pigments, and bioactive compounds, offers opportunities for biotechnological applications. The extraction and utilization of X. caffra oil as a potential biodiesel feedstock can contribute to renewable energy sources. Additionally, the pigments present in X. caffra stem bark can be explored for natural dye production, providing environmentally friendly alternatives to synthetic dyes.

Cultivation and commercialization of X. caffra can play a role in sustainable agriculture and economic development, especially in regions where it is indigenous and prevalent. The plant’s ability to thrive in arid and semi-arid environments, along with its versatile applications, makes it a valuable resource for local communities. Promoting the cultivation, processing, and marketing of X. caffra products can create income generation opportunities, improve food security, and support sustainable land use practices for both rural, and urban communities.

2.26 Postharvest practice of X. caffra fruit

Post-harvest practice, according to [50, 51], is a system for managing, storing, and moving agricultural products like fruits and vegetables following harvest. Fruit post-harvest quality is significantly influenced by environmental conditions, including temperature, humidity, the kind, and quantity of gases in controlled atmospheric storage [52]. Insufficient comprehension of efficient harvesting and storing methods, together with processing facilities, is required to gain a deeper comprehension of procedures for harvesting and storing of fruits of most underutilised crops such as X. caffra fruits [8]. Additionally, during the season of excess fruit, improper fruit processing and poor storage practices frequently results in significant fruit waste [52]. As a result, the development of an appropriate scientific postharvest process might extend fruit availability and lead to economic emancipation since communities can preserve fruit and sell them even during out of season, generating revenue to support their livelihoods and enhancing food accessibility [43]. Therefore, future research project on the postharvest treatments and management such as harvest technique, and postharvest storage will ensure that quality X. caffra fruits are preserved for longer period, subsequently, improve food availability and accessibility in society, especially those underprivileged community that depend on this fruit as source of food.

2.27 Processing of X. caffra value-added products and commercialisation

Value-added products are those products that have been manufactured through the conversion from raw material to another set of characteristics that is considered more desirable in the market [28]. Example of such potential product that could be developed from X. caffra includes alcohol, juice, jam, and nuts [43, 44, 53,54,55,56,57]. The advancement of society may be greatly improved by scientific studies that can makes it possible to process X. caffra into value-added products like juice, jam, nuts, and alcohol. The utilization of X. caffra will also improve because of this type of research, which will eventually eradicate malnutrition in underprivileged communities, while creating jobs as people will begin to produce and sell high-quality value-added products from X. caffra to support their way of life.

3 Conclusion

The X. caffra fruit, which is underutilised is abundant in a number of biochemical components, such as, calcium, flavonoids, magnesium, potassium, and phenols. These biochemicals are crucial for preventing most diseases and enhancing human health and nutrition. The fruit processing business still has a lot of room to explore and use the bioactive components of the X. caffra fruit. Consuming X. caffra fruit, which is rich in several biochemical substances, is linked to both the prevention and treatment of several diseases, including heart disease, wound healing, gum bleeding, and wound healing. The health benefits of X. caffra fruit have not been extensively established, little is known about the growth, yield, biochemical and metabolite profiles of this fruit when grown under various agronomic conditions, such as varying irrigation levels, fertilizer types, and soil types. Therefore, more research in this area is still necessary. Furthermore, it is important to extract the biochemical constituents of the X. caffra fruit and utilise them as functional ingredients in a variety of culinary items. By promoting the sale of items from X. caffra, this will benefit both human health and the struggling rural economy, where food scarcity is still a challenge.