Journal of Functional Foods 75 (2020) 104220 Contents lists available at ScienceDirect Journal of Functional Foods journal homepage: www.elsevier.com/locate/jff Southern African indigenous fruits and their byproducts: Prospects as food T antioxidants Trust M. Pfukwaa, Obert C. Chikwanhab, Chenaimoyo L.F. Katiyatiyab, Olaniyi A. Fawolec, ⁎ Marena Manleya, Cletos Mapiyeb, a Department of Food Science, Faculty of AgriSciences, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch 7602, South Africa b Department of Animal Sciences, Faculty of AgriSciences, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch 7602, South Africa c Postharvest Research Laboratory, Department of Botany and Plant Biotechnology, Faculty of Science, University of Johannesburg, Private Bag 524, Auckland Park 2006, South Africa ARTICLE INFO ABSTRACT Keywords: The discourse regarding plant-based preservatives for food application has generally revolved around extracts Antioxidants from commercial fruits, vegetables, herbs and spices with indigenous fruits (IFs) on the periphery, with little Bioprospecting investment into their valorisation. While being important food sources at community level, IFs and their by- Indigenous fruit products are also incorporated into medicinal remedies, combating various diseases. Their ethnomedicinal usage Bioeconomy indicates potent bioactive profile that alleviate effects of oxidative stress, which accompany diseasein vivo. This is supported by in vitro antioxidant activity of the IFs and their byproducts. As such, the current review explores the potential of bioprospecting extracts from nine IFs and their byproducts as food antioxidants. Evidence presented shows that IFs have high content of bioactive compounds further translating to high antioxidant activity. Research gaps in information concerning in vitro bioactivity warrant further research to provide impetus for valorisation and food application of IFs. 1. Introduction Nguyen et al., 2016; Van Vuuren & Frank, 2020). In terms of IFs, ‘by- products’ refer to the parts of the fruit which are left after consumption In sub-Saharan Africa, indigenous fruits (IFs) play a pivotal role in or juice extraction such as the skin/peel, pulp, seed or stones. In- society (Stadlmayr, Charrondière, Eisenwagen, Jamnadass, & digenous fruits and their phytochemical extracts have been used as Kehlenbeck, 2013; Van Wyk, 2011). In the Global South, IFs native to a remedies for several diseases, such as sinusitis, fever, asthma, diarrhea, country have remained on the societal and economic fringes and are indigestion and skin diseases (Castañeda-Loaiza et al., 2020; Khoo, still relatively unknown in the commercial market (Mabhaudhi et al., Azlan, Kong, & Ismail, 2016; Van Vuuren & Frank, 2020). This asso- 2019). They contribute to a small share of global food systems with ciation is important since these remedies offer the antioxidant and/or limitations being attributed to lack of seed production systems, antimicrobial effects required to counter the oxidative stress and mi- breeding and agronomic improvement technologies (Kasolo, crobial infections that accompany these ailments (Moyo, Finnie, & Van Chemining’wa, & Temu, 2018). Additionally, there is an observed lack Staden, 2011; Van Der Watt & Pretorius, 2001; Van Vuuren & Frank, of access to market information, low level of acceptability and access, 2020). In addition, many plants have been used as sources of eco- strong deficiencies in processing technologies and skills, and inherently nomically important constituents for incorporation into fragrances, weak value chains to propel the IFs to wider commercial markets pharmaceuticals, pesticides, food flavours and preservatives Maroyi,( (Kasolo et al., 2018; Omotayo & Aremu, 2020). Gaps in knowledge 2019; Mokoka, Mcgaw, Eloff, Mcgaw, & Programme, 2010; Stevenson, concerning IFs should be addressed to promote and expand their use in Isman, & Belmain, 2017). food applications. Overall, IFs and their byproducts remain undervalued and under- While the central aspect to the importance of IFs and their by- utilised resources and there is little documentation on their phyto- products has been the provision of food, they have also been used as chemical composition and bioactivity (Kasolo et al., 2018). In many medicinal remedies for animal and human diseases (Maroyi, 2019; parts of Southern Africa, most IFs are still collected from wild trees and ⁎ Corresponding author. E-mail addresses: [email protected] (T.M. Pfukwa), [email protected] (O.C. Chikwanha), [email protected] (C.L.F. Katiyatiya), [email protected] (O.A. Fawole), [email protected] (M. Manley), [email protected] (C. Mapiye). https://doi.org/10.1016/j.jff.2020.104220 Received 27 July 2020; Received in revised form 18 September 2020; Accepted 23 September 2020 1756-4646/ © 2020 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/). T.M. Pfukwa, et al. Journal of Functional Foods 75 (2020) 104220 Table 1 Current uses of indigenous fruits and their byproducts. Fruit Food uses of indigenous fruit Medicinal uses of indigenous fruit Medicinal properties of other plant parts of Citation and byproducts indigenous fruit trees Carissa Eaten fresh Oleanolic acid and B-amyrin Leaves are used against diarrhoea in Moodley et al. (2011), macrocarpa (Amathungulu) • Preparation of fruit salad, • from the fruit can be used as a • livestock Mphaphuli et al. (2020), • jam, pies, sauces, desserts, natural alternative to aspirin Souilem et al. (2019) yoghurt, jellies and ice cream Used as topping for cakes • and puddings Carpobrotus edulis Eaten fresh Treats tuberculosis, respiratory Leaf juice used: Castañeda-Loaiza et al. (Hottentot-fig) • Preparation of jam, • infections, toothache, earache, • As a mouthwash for sore throat or gum (2020), Mudimba and • pickles or chutney facial eczema, wounds, burns, • infections Nguta (2019), Rocha et al. Consumed as a hypertension, and diabetes For the treatment of burn wounds. (2017), Van Der Watt and • dehydrated fruit snack or mellitus • To soothe pain from spider and tick bites. Pretorius (2001) cooked • For treatment against fungal and • bacterial infections, sinusitis, diarrhoea, infantile eczema, tuberculosis and internal chest conditions Osyris compressa (Cape Eaten fresh A paste of fruit is applied to the Boiled concoctions of the bark, mixed Shyaula (2012) sumach) • Skin and pulp of ripe fruit • forehead to relieve headache • with other herbs are used to improve • consumed fresh and used blood circulatory, digestive, respiratory to make jam and nervous systems Bark oils and paste used to treat skin • diseases such as infectious sores, ulcers, acne and rashes Diospyros whyteana Fruits are eaten as a snack No data Roots are used for treating dysmenorrhea, Verschaeve et al. (2004) (bladder nut) • • • irritating rashes and as an antibacterial Dovyalis caffra (Kei Preparation of juices and Juice from crushed fruit used to Roots and thorns used to treat Ngemakwe et al. (2017), apple) • liqueur • treat cough in livestock • amenorrhea and chest pains Aremu et al. (2019) Incorporated into fruit Fruit extract promotes Bark is used as a remedy for rheumatism • salads and desserts • gastrointestinal motility and • Made into syrups, inhibits tightening and • shortcake, jam, jelly, shortening of the uterine muscles drinks and pickles Added to porridge for • nutrient enrichment Seed roasted seed used as • coffee substitute Harpephyllum Fruit juice mixed with Fruits uses in the treatment of Stem bark used for treating acne, eczema, Maroyi (2019), Moodley caffrum (wild plum) • porridge to form a • skin problems (acne, eczema, • pain and childhood convulsions and et al. (2014), Ojewole and pudding-like product pimples, rash and skin cuts) and epilepsy Amabeoku (2007), Van Whole fruits processed wounds Aqueous stem-bark extracts have Vuuren and Frank (2020) • into syrups, jams, jellies, • anticonvulsant, and analgesic and blood liqueurs and novel flavors detoxification properties Olea europaea var. No data Ripe fruits boiled with sugar and Leaves extracts have antitumoral, anti- Long, Tilney, and Van Wyk cuspidata (wild olive) • • used as cough syrup • inflammatory, antioxidant, (2010), Msomi and Fruit infusion used for treating hepatoprotective, cardioprotective and Simelane (2017), Sánchez- • bloody stool and diarrhea in antimicrobial activities Quesada et al. (2013) humans Sclerocarya birrea (marula) Fruits processed into Fruits used in the treatment of Leaves and stem barks concoctions used Ojewole et al. (2010), • juice, jam, jellies, sorbet • goiter • to treat hypertension, diarrhoea, Sarkar et al. (2014), and alcoholic drinks indigestion, dysentery, ulcers, proctitis, Schulze-Kaysers, Leaves used to make tea diabetes mellitus, fever, malaria, fungal Feuereisen, and Schieber • infections and skin disease (2015) (continued on next page) 2 T.M. Pfukwa, et al. Journal of Functional Foods 75 (2020) 104220 Table 1 (continued) Fruit Food uses of indigenous fruit Medicinal uses of indigenous fruit Medicinal properties of other plant parts of Citation and byproducts indigenous fruit trees Syzygium guineense (water- Eaten fresh Treating infertility in women, Leaves are used for treating asthma, Nguyen et al. (2016), pear) • Fruit pulp used in the • treating wounds • dermatosis, malaria, pneumonia, Verschaeve et al. (2004) • preparation of juices, Fruits also used as a remedy for infertility fever, stomachache,