Food In sub-Saharan Africa Research Articles

Improved energy performance of small-scale pneumatic dryers used for processing cassava in Africa

Cassava (Manihot esculenta) is the most important staple food in sub-Saharan Africa. However, the shelf-life of the crop is short and, for this reason, the roots are usually processed into more stable products like cassava flour by village-based enterprises. Most of these enterprises use small-scale locally built pneumatic dryers, but such dryers still need further development, so the objective of this research was to improve their energy performance. Experiments were conducted at two cassava processing centres, one in Tanzania and one in Nigeria. Sensors were installed on the dryers, product samples were collected and the mass and energy balance of the equipment analysed, allowing the dryers' minimum air mass flow rates to be calculated. The air mass flow rates of both dryers were then reduced to a level approximating the minimum value. In Tanzania, the air mass flow rate of the dryer was reduced by 24%, while in Nigeria it was reduced by 14%. In both locations, the modifications decreased the dryers' heat input without jeopardising evaporation rates, and so not affecting the final moisture content of the dry products. Air temperatures at the dryer outlets decreased and relative humidity increased, while enthalpy remained unchanged. The energy required to evaporate 1 kg of water decreased by 20% in Tanzania and by 13% in Nigeria. The modification also improved energy efficiency by 25% in Tanzania and by 14% in Nigeria. However, in Nigeria, where yellow cassava flour was being used, the dryer modifications resulted in greater product colour losses.

Development of a nutrient-dense complementary food using amaranth-sorghum grains.

Thin porridge from cereals and starchy tubers is a common complementary food in Sub Saharan Africa. It may be high in antinutrients, low in energy, and nutrient density hence inadequate in providing infants' high energy and nutrients requirements per unit body weight. Consequently, undernourishment levels among children under 5 years are high. Therefore, there is need to avail nutrient‐dense complementary foods especially for children in low‐resource settings. The study was aimed at developing a nutrient‐dense complementary food from amaranth and sorghum grains. Amaranth grain, a pseudocereal, though rarely used as a complementary food in Kenya has a higher nutritional quality than other staples. Plant‐based foods are known to have high levels of antinutrients. Steeping and germination were used to reduce the levels of antinutrients and enhance the bioavailability of minerals in the grains. Various steeped and germinated amaranth and sorghum grains formulations were made to find the ratio with the highest nutrient content and lowest antinutrient levels. The 90% amaranth‐sorghum grains formulation had significantly (F = 32.133, P < 0.05) higher energy (5 kcal per g on dry weight basis) than the other formulations and a protein content of 14.4%. This is higher than the estimated protein needs from complementary foods even for a 12–23 months child of low breast milk intake (9.1 g/d). Antinutrients could not be detected which could imply enhanced nutrient bioavailability. Therefore, a nutrient‐dense complementary food product was developed from steeped and germinated amaranth and sorghum grains with 90% amaranth grain. In ready to eat form, it would give an energy content of 1.7 kcal per g (dilution of 1:2 amaranth‐sorghum flour to water) and 1.2 kcal per g (dilution of 1:4 amaranth‐sorghum flour to water). It can be used as a nutrient‐dense complementary food and for other vulnerable groups.

Food Inflation in Sub-Saharan Africa: Causes and Policy Implications

This paper analyzes food inflation trends in Sub-Saharan Africa (SSA) from 2000 to 2016 using two novel datasets of disaggregated CPI baskets. Average food inflation is higher, more volatile, and similarly persistent as non-food non-fuel (NF/NF) inflation, especially in low-income countries (LICs) in SSA. We find evidence that food inflation became less persistent from 2009 onwards, related to recent improvements in monetary policy frameworks. We also find that high food prices are driven mainly by non-tradable food in SSA and there is incomplete pass-through from world food and fuel prices and exchange rates to domestic food prices. Taken together, these finding suggest that central banks in low-income countries with high and persistent food inflation should continue to pay attention to headline inflation to anchor inflation expectations. Other policy levers include reducing tariffs and improving storage and transport infrastructure to reduce food pressures.

Food Inflation in Sub-Saharan Africa: Causes and Policy Implications

This paper analyzes food inflation trends in Sub-Saharan Africa (SSA) from 2000 to 2016 using two novel datasets of disaggregated CPI baskets. Average food inflation is higher, more volatile, and similarly persistent as non-food non-fuel (NF/NF) inflation, especially in low-income countries (LICs) in SSA. We find evidence that food inflation became less persistent from 2009 onwards, related to recent improvements in monetary policy frameworks. We also find that high food prices are driven mainly by non-tradable food in SSA and there is incomplete pass-through from world food and fuel prices and exchange rates to domestic food prices. Taken together, these finding suggest that central banks in low-income countries with high and persistent food inflation should continue to pay attention to headline inflation to anchor inflation expectations. Other policy levers include reducing tariffs and improving storage and transport infrastructure to reduce food pressures.

Verifying optimality of rainfed agriculture using a stochastic model for drought occurrence

It may be paradoxical but subsistence rainfed agriculture is the predominant source of food in Sub-Saharan Africa where the production uncertainty is associated with the stochastic nature of rainfall. This paper attempts to comprehend the rationale of this situation by a mathematical approach. Considering the level of drought severity as the zero-reverting Ornstein–Uhlenbeck process, optimality of rainfed agriculture is investigated in the context of stochastic control theory. Occurrence of drought terminating growth of crops is modelled with the concept of first exit time. A stochastic control problem allowing for virtual cost of irrigation, water stress to crops, and benefits of farming is formulated with irrigation effort as the control variable. The Hamilton–Jacobi–Bellman equation governing the optimal control is studied to identify the set of cost functions optimizing rainfed agriculture in an inverse problem approach. Data and information were collected in the coastal savanna agro-ecological zone of Ghana, to identify model parameters, formulate the stochastic control problem, solve the inverse problem, and then verify optimality of rainfed agriculture. The results indicated that rainfed agriculture is not optimal when the crop is more tolerant to water stress.

Exposure to aflatoxin B1 in utero is associated with DNA methylation in white blood cells of infants in The Gambia.

Exposure to environmental toxins during embryonic development may lead to epigenetic changes that influence disease risk in later life. Aflatoxin is a contaminant of staple foods in sub-Saharan Africa, is a known human liver carcinogen and has been associated with stunting in infants. We have measured aflatoxin exposure in 115 pregnant women in The Gambia and examined the DNA methylation status of white blood cells from their infants at 2-8 months old (mean 3.6 ± 0.9). Aflatoxin exposure in women was assessed using an ELISA method to measure aflatoxin albumin (AF-alb) adducts in plasma taken at 1-16 weeks of pregnancy. Genome-wide DNA methylation of infant white blood cells was measured using the Illumina Infinium HumanMethylation450beadchip. AF-alb levels ranged from 3.9 to 458.4 pg/mg albumin. We found that aflatoxin exposure in the mothers was associated to DNA methylation in their infants for 71 CpG sites (false discovery rate < 0.05), with an average effect size of 1.7% change in methylation. Aflatoxin-associated differential methylation was observed in growth factor genes such as FGF12 and IGF1, and immune-related genes such as CCL28, TLR2 and TGFBI. Moreover, one aflatoxin-associated methylation region (corresponding to the miR-4520b locus) was identified. This study shows that maternal exposure to aflatoxin during the early stages of pregnancy is associated with differential DNA methylation patterns of infants, including in genes related to growth and immune function. This reinforces the need for interventions to reduce aflatoxin exposure, especially during critical periods of fetal and infant development.

Inorganic arsenic in starchy roots, tubers, and plantain and assessment of cancer risk of sub-Saharan African populations

Starchy roots, tubers, and plantain (RTP) are the staple food in sub-Saharan Africa (SSA), and also important energy sources in Asia, Europe, and America. In this work, inorganic arsenic (iAs) in these crops was separated and enriched by solid phase extraction (SPE), and quantified by hydride generation-atomic fluorescence spectrometry (HG-AFS). Overall, iAs in these crops ranged from 0.9 to 14.1 ng g−1 wet weight. Long-term cancer risk associated with iAs intake from these crops was assessed by Monte Carlo simulation based on iAs concentrations and historical consumption and population data. For 19 high RTP consuming SSA countries, life-time cancer risk was low with a mean target risk at 6.3 × 10−5 and a margin of exposure at 72.

Analysis of the contrast between natural occurrence of toxigenic Aspergilli of the Flavi section and aflatoxin B1 in cassava

Aflatoxin B1 (AFB1) is a carcinogenic mycotoxin produced by Aspergilli of the section Flavi that may contaminate food, in the field or during storage. Cassava represents an important staple food in sub-Saharan Africa. The analysis of aflatoxigenic fungi in 36 cassava samples obtained from producers in Benin indicated that 40% were contaminated by Aspergilli of the section Flavi. Upon morphological and molecular characterization of the 20 isolates, 16 belonged to Aspergillus flavus, 2 to Aspergillus parvisclerotigenus and 2 to Aspergillus novoparasiticus. This is the first time that this latter species is isolated from food. Although most of these isolates were toxigenic on synthetic media, no AFB1 contamination was observed in these cassava samples. In order to determine the action of cassava on AFB1 synthesis, a highly toxigenic strain of A. flavus, was inoculated onto fresh cassava and despite a rapid development, no AFB1 was produced. The anti-aflatoxin property was observed with cassava from different geographical origins and on other aflatoxigenic strains of the section Flavi, but it was lost after heating, sun drying and freezing.Our data suggest that fresh cassava is safe regarding AFB1 contamination, however, processing may alter its ability to block toxinogenesis leading to secondary contamination.

Cognitive Effects of Konzo

Konzo, an irreversible neuromotor disorder in children that has been linked to ingestion of bitter cassava root, a staple food in sub-Saharan Africa, also undermines cognitive function, even in those with no physical symptoms of the disease, report researchers from Michigan State University, East Lansing (Boivin MJ et al. Pediatrics. 2013;131[4]:e1231-e1239). Improperly prepared bitter cassava root has been linked to a neuromotor disorder called konzo and also may impair cognitive function.

Personal and Socio-Economic Factors Affecting the Adoption of Sweet Potato Production Technology by Farmers in South-East Zone of Nigeria

Sweet potato (Ipomoea batatas (L) Lam) is a very important staple carbohydrate food in sub-saharan Africa, and reputed for its capacity to tolerate marginal environments as well as high energy-fixing efficiency to produce high dry matter at a short period of time. It produces much dry matter per unit of time and contains high levels of vitamins A and C. Apart from the roots, the young leaves serve as green vegetable for man whereas the leaves and vines are cherished as fodder and hay by livestock. Sweet potato production technologies have been developed by the National Root Crops Research Institute, (NRCR) Umudike, and transferred to farmers in Nigeria in conjunction with state Agricultural Development Programmes. This study assessed the levels of awareness and adoption of the sweet potato technology disseminated by NRCRI to farmers and also determined the factors affecting the adoption of the technology. The multistage sampling technique was used in selecting the respondents using structured interview schedule as instrument. Data were collected from 270 respondents. The findings showed that the levels of awareness and adoption of the technologies were high. Age, education, riming experience, household size and farm size were factors that significantly influenced adoption, while the constraining factors to increased adoption of the technology were grouped into production complexity problems, economic problems, poor technical information and pathological problems. The study recommended the intensification of the dissemination of rapid vine multiplication techniques like the 2-node vine cutting technique, and rapid transfer of the integrated pest management technology on sweetpotato.Key words: Technology adoption, sweet potato, Ipomoea batatas

HIV and hepatocellular and esophageal carcinomas related to consumption of mycotoxin-prone foods in sub-Saharan Africa

Promotion of the HIV epidemic by aflatoxin is postulated but not yet established. Sub-Saharan populations commonly consume food contaminated by mycotoxins, particularly aflatoxins (predominantly found in peanut, maize, rice, and cassava) and fumonisins, which occur primarily in maize. Aflatoxin promotes hepatocellular cancer, and fumonisin may promote esophageal cancer. This analysis was undertaken to test the hypotheses that consumption of mycotoxin-prone staple foods is 1) related to the incidence of HIV infection in Africa and 2) related to "signature" cancer rates confirming exposure to aflatoxins and fumonisins. World Health Organization data for causes of death and the Food and Agriculture Organization per capita consumption data for commodities in sub-Saharan Africa were used. Per capita Gross Domestic Product and the percentage of Muslims (%Muslim) were the socioeconomic data sets exploited. Relations between causes of mortality, consumption of mycotoxin-prone foods, and socioeconomic variables were evaluated. Models for HIV transmission as a function of maize consumption and %Muslim were estimated. HIV and esophageal cancer deaths were significantly related to maize but were inversely related to %Muslim and rice consumption. HIV infections were minimized (74 compared with 435/100,000 people; odds ratio: 2.41; 95% CI: 1.73, 3.24; P < or = 0.0001) by the combination of low maize consumption and above-median % Muslim. Hepatocellular cancer deaths were positively related to rice but negatively related to maize consumption. HIV transmission frequency is positively associated with maize consumption in Africa. The relation between cancer and food suggests that fumonisin contamination rather than aflatoxin is the most likely factor in maize promoting HIV. Changes to the quality of maize may avoid up to 1,000,000 transmissions of HIV annually.

Irrigation Infrastructure Needed to Secure Self-sufficiency in Food in Sub-Saharan Africa

Irrigation Infrastructure Needed to Secure Self-sufficiency in Food in Sub-Saharan Africa

Determinants of the right of access to food in sub-Saharan Africa.

Food is one of the most important basic needs of human beings since it provides the energy for the physiological functioning of the body. The right to food is thus the right of all individuals alone or in community with others to enjoy physical and economic access to adequate food or the means for its procurement. Adequate food also implies the availability of food in sufficient quantity and quality to satisfy the dietary needs of all individuals and the accessibility of food in ways that are sustainable. Generally, a number of factors are considered important in the determination of the right of access to food. Key among these factors are availability of agricultural resources such as land, water, energy and fertilizer; increase in the demand for food as a result of the increase in population, increase in personal income, development of transportation and storage facilities, macroeconomic stability, sociopolitical stability; seasonal fluctuation in availability of food due to natural disaster, access to safe water, access to health care services, access to sanitation facilities and many others. This paper examines the extent to which these factors have impacted on the ability of the people in Sub-Saharan Africa to have access to food, using a set of cross-country data and a multiple regression analysis. The results obtained indicate that factors like the increase in population, access to sanitation facilities, access to safe water, access to health care services, access to information and increase in the price of food have to some extent impacted on the right of the people to have access to food inthe sub-region. Food supply, income of the people, the presence of democratic values, access to education and access to transport play little or no significant role in determining the right of the people to access food. Given these results, measures, such as, the provision of stable macroeconomics policies, reduction in income poverty, provision of basic social services and good governance were suggested as possible solutions to the right of access to food in Sub-Saharan Africa.

β-Carotene Micellarization during in Vitro Digestion and Uptake by Caco-2 Cells Is Directly Proportional to β-Carotene Content in Different Genotypes of Cassava ,

Cassava, a staple food in sub-Saharan Africa, does not provide adequate amounts of pro-vitamin A (VA) carotenoids and has been targeted for biofortification (i.e. selectively breeding cultivars of increased nutrient density with agroeconomically acceptable characteristics). However, the accessibility of pro-VA carotenoids for absorption in different cultivars of cassava remains unknown. Here, we used the coupled in vitro digestion/Caco-2 cell uptake model to screen the relative accessibility of β-carotene (βC) in 10 cultivars of cassava with varying concentrations of βC. After cooking (boiled for 30 min), the βC concentration in tubers from different cultivars ranged from less than detectable to 6.9 μg βC/g cassava. Samples were subjected to simulated oral, gastric, and small intestinal digestion to determine stability and micellarization of βC. All-trans βC, 9-cis βC, and 13-cis βC were the most abundant carotenoids in cooked cassava and recoveries after digestion exceeded 70%. Efficiency of micellarization of total βC was 30 ± 2% for various cultivars with no significant difference in isomers and linearly proportional to concentration in cooked cassava (r = 0.87; P < 0.001). Accumulation of all-trans βC by Caco-2 cells incubated with the diluted micelle fraction for 4 h was proportional (R2 = 0.99; P < 0.001) to the quantity present in micelles. These results suggest that all-trans βC content appears to provide the key selection marker for breeding cassava to improve VA status and that the more complicated screening procedure using in vitro digestion coupled to cell uptake does not provide additional information on potential bioavailability.

Aflatoxin Exposure in Developing Countries: The Critical Interface of Agriculture and Health

Aflatoxins are common contaminants of staple foods in sub-Saharan Africa. These toxins are human liver carcinogens, especially in combination with chronic infection with hepatitis B virus. However, in an agricultural setting, the effects on growth, immune status, and susceptibility to infectious disease in farm animals are also well recognized. These latter effects have been far less explored in human populations. To review some of the more recent work on aflatoxins where the health outcomes seen in the agricultural setting, including growth impairment and immune suppression, have been investigated in human populations. The paper draws largely on examples from West Africa. The paper also sets out how knowledge gained about aflatoxins in the agricultural setting can be used to design intervention studies in human populations. A review of the relevant literature. Human exposure to aflatoxins begins early in life, and recent studies in West Africa have demonstrated an association between exposure and growth faltering, particularly stunting, in young children. At present the underlying mechanisms for the latter effects are unknown but may include impairment of immunity and increased susceptibility to infections. Simple postharvest intervention strategies were successful in reducing aflatoxin exposure in a subsistence farm setting, providing a rationale for prevention of aflatoxin-related disease. There are potential benefits to public health from intervention strategies combining expertise in the agricultural and health settings to address the aflatoxin problem.

Yields and accumulations of N and P in farmer-managed intercrops of maize–pigeonpea in semi-arid Africa

Maize (Zea mays L.) is a major staple food in Sub-Saharan Africa but low soil fertility, limited resources and droughts keep yields low. Cultivation of maize intercropped with pigeonpea (Cajanus cajan L. Millsp.) is common in some areas of eastern and southern Africa. The objectives of this study were (1) to investigate dry matter, nitrogen (N) and phosphorus (P) accumulation in different plant components of maize–pigeonpea intercropping systems and (2) to report the effects of the intercrops on soil fertility. Maize–pigeonpea intercrops were compared to sole maize grown using farmersȁ9 practices. Intercropping maize and pigeonpea increased (P 0.11). Nitrate and ammonium levels in soil were still not affected by the treatments after the soils were incubated in anaerobic conditions for 8 days at 37°C (P > 0.11). However, pigeonpea added up to 60 kg of N ha−1 to the system and accumulated up to 6 kg of P ha−1 and only 25% of this N and P were exported in the grain. In conclusion, beside the added grain yield of pigeonpea in the intercropped systems, pigeonpea increased the recirculation of dry matter, N and P, which may have a long-term effect on soil fertility. Furthermore, the stems from pigeonpea contributed to household fuel wood consumption. The intercropped system thus had multiple benefits that gave significant increase in combined yield per unit area without additional labour requirements. The main requirement in order to up-scale the maize–pigeonpea intercropping approach is sufficient supply of high-quality pigeonpea seeds.

Insects as Food in sub-Saharan Africa

Data on insects as food in sub-Saharan Africa were collected by reviewing the literature and conducting interviews in a number of African countries. A list of about 250 edible insect species from Africa was compiled. Of these, 78 percent are Lepidoptera (30%), Orthoptera (29%) and Coleoptera (19%), and 22 percent Isoptera, Homoptera, Hymenoptera, Heteroptera, Diptera and Odonota. Insects are rich in protein, vitamins and minerals, and a good source of iron and B-vitamins. Examples of insects being toxic are given, but often traditional methods are used to remove the poison. Whether or not insects are eaten depends not only on taste and nutritional value, but also on customs, ethnic preferences or prohibitions. The harvesting of insects is often done by women. The way of collecting depends on insects' behaviour. For example, inactivity at low temperatures enables easy catching of locusts and grasshoppers in the morning. Night flyers (termites, some grasshoppers) can be lured into traps by light and some insects like palm weevils can be attracted to artificially created breeding sites. Some species (crickets, cicadas) can be located by the sound they make. A number of tools are used to facilitate capturing such as glue, sticks, nets and baskets. Because most insects are only seasonally available, preservation by drying is often practised. Some examples of how to prepare them as food are given from important insect groups. To manage insects in the interest of food security more attention should be given to environmentally sustainable harvesting methods. They should be made better available throughout the year by developing improved conservation methods or by farming this minilivestock. Considering the economic, nutritional and ecological advantages of this traditional food source, its promotion deserves more attention both from national governments and assistance programmes. Resume—Des donnees sur le role des insectes dans l'alimentation humaine ont ete collectees dans la litterature et lors d'enquetes effectuees dans un certain nombre de pays africains. Une liste d'environ 250 insectes comestibles a ete etablie. Soixante dix-huit pour cent sont des Lepidopteres (30%), Orthopteres (29%) et Coleopteres (19%) et 22% sont des Isopteres, Homopteres, Hymenopteres, Heteropteres, Dipteres et Odonotes. Les insectes sont riches en proteines, vitamines et mineraux et sont des sources importantes de fer et de vitamine B. Des examples d'insectes toxiques sont cites mais dans de nombreux cas des methodes traditionnelles sont utilisees pour eliminer les toxines. Les insectes sont consommes ou non en fonction des traditions, des preferences ethniques ou des interdictions. La recolte des insectes est souvent effectuee par les femmes. La facon de recolter depend du comportement des insectes, par exemple, l'inactivite de certains insectes a basse temperature (criquets et sauterelles) les rend vulnerables a la recolte le matin; les insectes nocturnes volants

Production of exopolysaccharides by lactic acid bacteria isolated from traditional fermented foods in Nigeria

Lactic acid bacteria isolated from traditional fermented foods in Nigeria were investigated for their ability to produce exopolysaccharides (EPS). The test organisms were chosen after screening in a modified exopolysaccharide selection medium (mESM). The ability of the test organisms to produce EPS in whey medium (WM) and supplemented whey media (SWM I, SWM II) with combinations of lactose, KH2PO4, NH4Cl, casamino acids, mineral salts and yeast extract was determined. Amongst the test isolates, only Leuconostoc mesenteroides (from sorghum ogi) and Lactobacillus plantarum (from maize ogi) demonstrated the highest form of EPS production. Adjustment of the pH of SWM II to 6.2 increased the viscosity relative to that of SWM I (5.7) that was not adjusted. The effect of incubation temperature showed that at 25 °C, the viscosity was higher for L. mesenteroides and L. plantarum than at 30 and 40 °C. However, the biomass yield was lower, the least lactose was utilized and less lactic acid was produced at this temperature. More galactose and glucose were liberated at 30 °C that at 25 and 40 °C. This paper suggested that the viscous nature of some traditional foods in sub-Saharan Africa may be partly due to excretion of polysaccharides during the fermentation processes.

Irrigation and Rural Development to Secure Self-sufficiency in Food in Sub-Saharan Africa

Irrigation and Rural Development to Secure Self-sufficiency in Food in Sub-Saharan Africa

Yeasts in the traditional brewing of pito in Ghana

Yeasts from pito, a cereal-based traditional alcoholic beverage were isolated and characterized using biochemical and physiological tests. A total of 21 strains belonging to 8 genera were identified as Saccharomyces cerevisiae (8), Candida tropicalis (4), Kloeckera apiculata (2), Hansenula anomala (2), Torulaspora delbrueckii (3), Schizosaccharomyces pombe (1) and Kluvyeromyces africanus (1). Various diluents used for a 2 h holding period shows that 0.1% malt extract and peptone gave 20% decrease in cell viability for all the isolates, while phosphate buffer least supported the survival of the yeast cells with about 90% decrease in cell viability obtained for S. pombe at the end of the 2 h holding period. The effect of pH and temperature on the growth of the isolates revealed that at relatively low temperatures, growth increased with increasing pH, but a decrease was observed with increasing pH at high temperatures for S. cerevisiae and Candida tropicalis. All the isolates demonstrated good growth (102 to 106 c.f.u./ml) at 10% ethanol concentration over a period of 8 days incubation. However, growth of K. africanus was completely inhibited after 4 days incubation period. The quality indices of the beverage produced using S. cerevisiae as a single-starter organism compared favourably with the traditional brew. The paper suggests ways of scientifically regulating the production of fermented foods in sub-Saharan Africa.