Value Addition of Southern African Monkey Orange (Strychnos Spp.): Composition, Utilization and Quality Ruth Tambudzai Ngadze
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Value addition of Southern African monkey orange ( Value addition of Southern African monkey orange (Strychnos spp.): composition, utilization and quality Strychnos spp.): composition, utilization and quality Ruth Tambudzai Ngadze 2018 Ruth Tambudzai Ngadze Propositions 1. Food nutrition security can be improved by making use of indigenous fruits that are presently wasted, such as monkey orange. (this thesis) 2. Bioaccessibility of micronutrients in maize-based staple foods increases by complementation with Strychnos cocculoides. (this thesis) 3. The conclusion from Baker and Oswald (2010) that social media improve connections, neglects the fact that it concomitantly promotes solitude. (Journal of Social and Personal Relationships 27:7, 873–889) 4. Sustainable agriculture in developed countries can be achieved by mimicking third world small-holder agrarian systems. 5. Like first time parenting, there is no real set of instructions to prepare for the PhD journey. 6. Undertaking a sandwich PhD is like participating in a survival reality show. Propositions belonging to the thesis, entitled: Value addition of Southern African monkey orange (Strychnos spp.): composition, utilization and quality Ruth T. Ngadze Wageningen, October 10, 2018 Value addition of Southern African monkey orange (Strychnos spp.): composition, utilization and quality Ruth Tambudzai Ngadze i Thesis committee Promotor Prof. Dr V. Fogliano Professor of Food Quality and Design Wageningen University & Research Co-promotors Dr A. R. Linnemann Assistant professor, Food Quality and Design Wageningen University & Research Dr R. Verkerk Associate professor, Food Quality and Design Wageningen University & Research Other members Prof. M. Arlorio, Università degli Studi del Piemonte Orientale A. Avogadro, Italy Dr A. Melse-Boonstra, Wageningen University & Research Prof. Dr R. Ruben, Wageningen University & Research Dr T. J. Stomph, Wageningen University & Research This research was conducted under the auspices of the Graduate School VLAG (Advanced studies in Food Technology, Agrobiotechnology, Nutrition and Health Sciences) ii Value addition of Southern African monkey orange (Strychnos spp.): composition, utilization and quality Ruth Tambudzai Ngadze Thesis submitted in fulfilment of the requirements for the degree of doctor at Wageningen University by the authority of the Rector Magnificus Prof. Dr A.P.J. Mol, in the presence of the Thesis Committee appointed by the Academic Board to be defended in public on Wednesday 10 October 2018 at 4 p.m. in the Aula. iii Ruth T. Ngadze Value addition of Southern African monkey orange (Strychnos spp.): composition, utilization and quality, 179 pages. PhD thesis, Wageningen University, Wageningen, the Netherlands (2018) With references, with summary in English ISBN: 978-94-6343-506-2 DOI: https://doi.org/10.18174/459128 iv Table of Contents Chapter 1 General introduction ............................................................................... 1 Chapter 2 Local processing and nutritional composition of indigenous fruits: the case of monkey orange (Strychnos spp.) from Southern Africa ........................... 19 Chapter 3 Improvement of traditional processing of local monkey orange (Strychnos spp.) fruits to enhance nutrition security in Zimbabwe ....................... 45 Chapter 4 Effect of heat and pectinase maceration on phenolic compounds and physicochemical quality of Strychnos cocculoides juice ...................................... 71 Chapter 5 Monkey orange fruit juice improves the nutritional quality of a maize-based diet .................................................................................................... 93 Chapter 6 General discussion .............................................................................. 113 References ........................................................................................................... 137 Summary .............................................................................................................. 155 Acknowledgements ............................................................................................. 161 About the author .................................................................................................. 165 Curriculum vitae .................................................................................................. 166 Overview of completed training activities .......................................................... 167 v vi Chapter 1 General introduction 1 Chapter 1 General Introduction 1.1 Importance of indigenous fruits in sub-Saharan Africa About 815 million people had insufficient food and were affected by hunger in 2016, with the majority of these people living in developing countries (FAO et al., 2017). The situation in sub-Saharan Africa is worsened by the multiple burden of malnutrition: undernutrition, overweight / obesity and micronutrient (i.e. vitamin A and the minerals Fe, I and Zn) deficiencies, referred to as hidden hunger (FAO, 2017). In 2016, the prevalence rate of undernutrition in the sub-Saharan Africa region was 22.7 %. Iron deficiency, commonly known as anaemia, affected 39 % of women in the child-bearing age, while one in three children under the age of five was stunted and 11.8 % were overweight in Southern Africa (FAO, 2017; FAO et al., 2017). Mineral malnutrition is rife in rural communities because households rely heavily on cereals, roots and tubers as staples leading to diets that lack nutritional diversity (Allen et al., 2006). Simultaneously, the high starch diets also contribute to overweight and obesity due to the imbalance between excessive calorie/energy intake and expenditure (Joint FAO and WHO, 2005). Various studies have been conducted that ascertain non-timber forest products (NTFPs) as a means of diet diversification and nutrient source (FAO, 1996). NTFPs already play a traditional role as food sources throughout the tropics and add to food security in dry periods. Among NTFPs, indigenous edible fruits are occasionally used to meet food shortages and they remain a major option for coping with micronutrient deficiencies in diets of rural households in the semi-arid areas of Southern Africa during vulnerable times (Laverdière & Mateke, 2003). Indigenous edible fruits have also been adapted over time to food needs, habits and tastes of traditional societies in their own localities (Gomez, 1988). International recognition and trade of wild fruits have increased in the past decades for fruits such as Araca-pera (Psidium acutangulum), cherimoya fruits (Annona cherimola) and especially acai berry (Euterpe oleracea) from the Amazon forest. These fruits have been reported to have antioxidant activity comparable to some reported so-called super fruits (Gruenwald, 2009; Li et al., 2016). Similar fruits exist in the semi-arid areas of Africa and have been accepted, cultivated and marketed internationally, especially in Europe, Japan, New Zealand and the USA for their high nutrient contents and specific 2 Chapter 1 General Introduction ingredient uses, e.g. horned melon (Cucumis metulifer) trade marketed as Kiwano, melon (Cucumis melo), marula (Sclerocarya birrea) and tamarind (Tamarindus indica) (National Research Council, 2008). Though not yet cultivated commercially, baobab (Adansonia digitata) has also recently entered the European market as a food ingredient because of, among other factors, its high vitamin C and antioxidant content (Gruenwald, 2009). These developments have created a new impetus to the potential role of unexploited wild indigenous fruits for use as ingredients in the production of functional foods for local communities with promising prospects for global recognition and trade. In Zimbabwe, over 180 wild food plants were inventoried, of which indigenous fruit trees comprise about 20 % (Akinnifesi et al., 2006; Tredgold, 1986). From these, a number of indigenous fruits have been prioritized for their potential to improve malnutrition problems, especially for rural communities in Zimbabwe. The International Centre for Underutilised Crops (ICUC), nowadays called Crops for the Future, in partnership with The World Agroforestry Centre and the International Plant Genetic Resources Institute through their ‘Fruits for the Future’ program initiated domestication of indigenous fruit trees (IFTs) and knowledge dissemination programs. The premise of the program was that the health and livelihood of communities could be improved by reduced dependency on expensive exotic fruit imports, through substitution with locally available, cheaper indigenous fruits that the community ranks as important. Indigenous fruits were therefore selected based on farmers’ preferences for domestication, ease of access, social and economic importance (Laverdière & Mateke, 2003). 1.1.1 Nutritional relevance of indigenous fruits Fruits are widely recommended sources of minerals, vitamins and phytochemicals, which confer health benefits and reduction in disease risks. Minerals have important physiological roles in human health. Generally minerals have important physiological roles in cognitive skills, learning abilities, body growth and bone formation, essential for proper development of infants and children. Iron and Zn mineral deficiencies, which are very common in sub-Saharan Africa, can result in deleterious effects on the normal functioning of the human body related to the risk of a number of health consequences such as child stunting, anaemia and depressed functioning of the immune system,