Improvement of Maize-Based Foods in Sub-Saharan Africa Onu Ekpa Wageningen, 28Th August 2020
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Propositions 1. Disconnection between maize breeders and end users is very costly. (this thesis) 2. Gluten-free bread can be made from maize using sourdough technology. (this thesis) 3. Humankind is coded to multiply beyond its limit but the efforts of both the “wizards and prophets” distinguishes our fate from Oostvaardersplassen’s red deer. 4. Homo sapiens will become extinct in the futuristic world of the designer baby. 5. Your ghost continues writing in the middle of the night. 6. Storytelling gives science its soul. Propositions belonging to the thesis, entitled Improvement of maize-based foods in Sub-Saharan Africa Onu Ekpa Wageningen, 28th August 2020. Improvement of maize-based foods in Sub-Saharan Africa Onu Ekpa Thesis committee Promotor Prof. Dr V. Fogliano Professor of Food Quality and Design Wageningen University & Research Co-promotor Dr A. R. Linnemann Associate professor, Food Quality and Design Group Wageningen University & Research Other members Prof. Dr R. Ruben, Wageningen University & Research Prof. Dr E. Vittadini, University of Camerino, Italy Prof. Dr M.J. Kropff, International Maize and Wheat Improvement Centre (CIMMYT), Mexico City, Mexico Dr E.F. Talsma, 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) Improvement of maize-based foods in Sub-Saharan Africa Onu Ekpa 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 Friday 28 August 2020 at 4 p.m. in the Aula. Onu Ekpa Improvement of maize-based foods in Sub-Saharan Africa, 227 pages. PhD thesis, Wageningen University, Wageningen, the Netherlands (2020) With references, with summary in English ISBN: 978-94-6395-440-2 DOI: https://doi.org/10.18174/525331 Table of contents Chapter 1 General introduction and thesis outline 9 Chapter 2 Sub-Saharan African maize-based foods - processing 27 practices, challenges and opportunities Chapter 3 Sub-Saharan African maize-based foods: Technological 71 perspectives to increase the food and nutrition security impacts of maize breeding programmes Chapter 4 Identification of the volatile profiles of 22 traditional and 99 newly bred maize varieties and their porridges by PTR- QiTOF-MS and HS-SPME/GC-MS Chapter 5 Carotenoid stability and aroma retention during the post- 125 harvest storage of biofortified maize Chapter 6 Genotype selection influences the quality of gluten-free 149 bread from maize Chapter 7 Influence of exopolysaccharides produced by lactic acid 169 bacteria on the quality of maize bread Chapter 8 General discussion 195 General Summary 219 Acknowledgement 221 About the Author 225 List of publications 226 Overview of training activities 227 CHAPTER 1 General introduction and thesis outline 9 General introduction 1.1 Trends in cereal production and consumption in Africa The predominant cereal crops in Africa are maize, rice, wheat, sorghum and millet, with maize contributing 45% of the cereal production and mostly being used as food [1-3], (Figure 1.1). In 2018, worldwide maize production was 1,074 million tonnes (MT), with the United States, China, Brazil and Mexico producing 34.4% (370 MT), 20.7% (223 MT), 8.3% (90 MT) and 2.4% (26 MT), respectively.[3] Africa as a whole produces 8% (84 MT) of the total world production. South Africa and Nigeria are the largest producing countries in Africa, with an average production of 15 MT and 11 MT, respectively; together these countries account for 31% of Africa’s maize production.[3] Despite the huge production of maize in the United States and China, merely 34 and 18 g/person/day, respectively, is consumed as food in these countries. The per capita consumption of maize in Sub-Saharan Africa (SSA) is an average of 130 g/day, with values varying extensively. For instance, inhabitants of Lesotho consume 449 g/person/day, Malawians (359 g), Zambians (307 g), Zimbabweans (297 g) and South Africans (271 g).[2] These figures signify the paramount importance of maize in the daily diet of Africans. Africa uses more than 80% of its maize production as food, contrary to other regions where maize is mostly reserved for animal feed, biofuel and industrial uses.[1, 4, 5] Production Food use Figure 1.1: Africa’s cereal production and food use. Adapted from OECD-FAO Agricultural Outlook 2018. The asymmetry in the production and food use of cereals in Africa needs a change to avert an impending food security crisis. For instance, production of wheat (Figure 1.2 - chart A) is low but wheat remains the predominantly consumed cereal, mainly for bakery use, pasta and noodles (Figure 1.2 - chart B). SSA produces 1.0 % of world wheat production and 23.7% of Africa’s production.[6] As the agro-ecological conditions in SSA are generally unsuitable for wheat production, African countries depend on importation to cater for the ever-rising drive for food produced from crops not sufficiently grown locally. This unsustainable trend, if left unchecked, will continue to 10 Chapter 1 hurt the economy and possibly trigger food crises - not ruling out uprising and riots as observed in Mozambique, Sudan, Zimbabwe and during the popular “Arab spring”. Import dependent staple crop economy often prompt supply issues and high price volatility causing food insecurity and driving social unrest. The trend raises the need to find solutions to issues related to poor shelf life, poor baking properties, food safety, a decrease of nutritional value and sensory properties of maize (and other resilient and climate-smart indigenous crops) for baked foods, particularly bread making. Figure 1.2: Projected cereal production (chart A) and food use (chart B) in SSA. Adapted from OECD-FAO Agricultural Outlook 2018. Maize is an integral part of the daily diet of many Africans, serving as a significant source of energy and protein, albeit heavy reliance can result in malnutrition due to natural deficiencies of some nutrients or losses during post-harvest handling. This buttresses the need for continued investigation of feasible ways to improve the nutritional values of maize foods, enhance maize food diversity as well as encourage acceptance of nutrient-dense varieties, which is the overarching aim of this thesis - improvement of maize- based foods in Sub-Saharan Africa. 1.2 Contribution of maize to the daily diet of Africans 1.2.1 Caloric intake Cereals account for about 80% of the total caloric intake in Africa, with maize as the major contributor. Maize contributes as much as 55% of the total energy consumption in Lesotho, 50% in Zambia, 49% in Malawi, 40% in Zimbabwe and 31% in Kenya.[2, 7] The presented consumption data are based on average national figures. Region-specific data could show higher diversity; for example, in Chongwe district of Zambia, maize contributes for at least 75% to the total energy intake [8] and a vast multicultural country like Nigeria could even show a wider diversity. Maize supplies on average 363 kcal/100 g [7, 9]; less than 200 g/capita/day of maize is needed to meet the 130 g Recommended Dietary Allowance (RDA) for carbohydrates.[10] People in some countries in SSA are now consuming far more than this amount. Therefore, in these countries, assorted 11 General introduction energy sources in the meal are needed, rather than an increase in maize consumption. According to the OECD agricultural projection 2018 – 2027, Africa will experience a continuous rise (1.5 - 2.5% per annum) in the production of legumes, meat, fish and dairy products.[3] This demonstrates the available potential for food diversification to address malnutrition or hidden hunger that may result from over-reliance on maize meal. 1.2.2 Protein and essential amino acids Maize accounts for more than 30% of the total daily protein intake in Kenya, Lesotho, Malawi, Zambia, Zimbabwe and Swaziland.[2] Since the protein in maize is poor in essential amino acids (e.g. lysine and tryptophan), people who highly depend on maize for their nutrition may incur problems associated with protein deficiencies.[11] This is particularly relevant since the available protein can be lost during traditional processing.[12] However, quality protein maize (QPM) has higher amounts of lysine and tryptophan due to an about 50% reduction in the level of zein.[13] Assuming an average maize intake of 130 g/person/day [2] in Africa and an 80% nutrient retention after cooking, both adults and children are not able to meet the RDA for protein through maize intake, see Table 1.1. A child (1–2 yr.) can derive all the needed amino acids from quality protein maize (QPM) except for lysine (i.e. an additional intake of 43 g per day is needed to meet the lysine requirement), while only threonine and leucine can be sufficiently derived from conventional maize. An adult is not able to meet the daily dietary requirement for protein and all essential amino acids (e.g. an adult requires an impossibly high additional intake of 775 g of conventional maize or 543 g QPM to meet the daily requirement for lysine). Although protein and amino dietary requirements cannot be achieved by either the normal and QPM varieties, it is obvious that a lower quantity of protein from maize is needed when other quality protein staple crops are available.[13] 12 Chapter 1 Table 1.1: Estimated daily intake (g) from common and quality