Elemental composition of teff (a gluten-free grain), maize and wheat: Staple crops in the Main Ethiopian Rift Valley

Optimization of Nutritional and Sensory Properties of Unleavened Flatbread Developed From Maize-Boiled Rhizome of Water Lily-Fish

The aim of this study was to optimize nutritional composition, mineral contents, and overall sensory acceptability of unleavened flatbread developed from maize, boiled rhizome of water lily, and dried fish fillet powder. A mixture containing 50%-80% maize, 15%-30% boiled water lily rhizome, and 5%-20% dried fish fillet powder was mixed using the D-optimal mixture design. Flatbread developed from maize flour was used as the control. The results showed that the linear model described well changes in crude protein, total carbohydrate, gross energy value, sodium, potassium, iron, and zinc. The lack of fit was non-significant (p > 0.05) for all the linear models, indicating that the linear model equations fit the data well. The addition of boiled rhizome of water lily flour and dried fish fillet powder to maize improved protein content, potassium, calcium, magnesium, iron, and zinc but decreased fat, fiber, carbohydrate, and gross energy value. Numerical optimization results showed that a blending ratio containing 62.62% maize, 29.92% boiled rhizome of water lily, and 7.45% dried fish fillet powder resulted in the best formulation with a desirability function value of 0.516. It can be concluded that this bread can potentially reduce protein energy malnutrition and micronutrient deficiencies.

Impact of manure and artificial fertilizer application on metal and metalloid distributions in agricultural soils and crops

The application of animal manure to agricultural soil is a very common practice to improve soils fertility, providing a rich source of organic matter and nutrients. However, the presence of certain trace elements in the manure can result in a threat for food safety and the environment. In addition to their potential toxic effects on crops, animal and humans, certain metals such as cadmium, chromium, copper, nickel, mercury, cobalt, lead and zinc may play a role in the emergence and spread of antibiotic resistance, as they can increase the selective pressure on bacteria. To evaluate holistically the impact of manure application on the concentration of metals and metalloids (metal(loid)s) in different environmental compartments, samples of manure, farmed and wild animal faeces, soils, crops and water were collected from farming environments in Austria, Czech Republic, Estonia, Portugal, Republic of Ireland and Great Britain. Inductively coupled plasma mass spectrometry was used to quantify 17 elements, namely vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, arsenic, selenium, strontium, molybdenum, cadmium, mercury, antimony, barium, and lead. The data were analysed using Pearson correlation and Principal Components Analysis (PCA). The statistical analyses revealed that zinc, copper and potentially manganese can be used as markers of the presence and impact of manure in the environment. Minimum co-selective concentrations (MCC) for copper and zinc were exceeded in water and manure samples, indicating that these elements may act as drivers for bacterial antibiotic resistance. However, the results of the total concentration of metal(loid)s in crops and the bioavailable concentrations in soils did not show any significant differences between application of manure and artificial fertilizers. Other confounding effects, such as the soil matrix and/or the type of crops, seem to have a more significant effect on the concentration and distribution of the metal(loid)s in these systems.

Biggest of tinies: natural variation in seed size and mineral distribution in the ancient crop tef [Eragrostis tef (Zucc.) Trotter]

Tef [Eragrostis tef (Zucc.) Trotter] is the major staple crop for millions of people in Ethiopia and Eritrea and is believed to have been domesticated several thousand years ago. Tef has the smallest grains of all the cereals, which directly impacts its productivity and presents numerous challenges to its cultivation. In this study, we assessed the natural variation in seed size of 189 tef and 11 accessions of its wild progenitor Indian lovegrass (Eragrostis pilosa (L.) P. Beauv.) and explored the mineral distribution of representative accessions. Our findings revealed significant natural variation in seed size and mineral concentration among both the tef and E. pilosa accessions. We observed significant variation in seed length, seed width, and seed area among the accessions of both Eragrostis spp. we analyzed. Using representative accessions of both species, we also found significant variation in 1000-grain weight. The observed variation in seed size attributes prompted us to use comparative genomics to identify seed size regulating genes based on the well-studied and closely related monocot cereal rice [Oryza sativa (L.)]. Using this approach, we identified putative orthologous genes in the tef genome that belong to a number of key pathways known to regulate seed size in rice. Phylogenetic analysis of putative tef orthologs of ubiquitin-proteasome, G-protein, MAPK, and brassinosteroid (BR)-family genes indicate significant similarity to seed size regulating genes in rice and other cereals. Because tef is known to be more nutrient-dense than other more common cereals such as rice, wheat, and maize, we also studied the mineral concentration of selected accessions using ICP-OES and explored their distribution within the seeds using synchrotron-based X-ray fluorescence (SXRF) microscopy. The findings showed significant variation in seed mineral concentration and mineral distribution among the selected accessions of both Eragrostis spp. This study highlights the natural variation in seed size attributes, mineral concentration, and distribution, while establishing the basis for understanding the genetic mechanisms regulating these traits. We hope our findings will lead to a better understanding of the evolution of tef at the genetic level and for the development of elite tef cultivars to improve seed size, yield, and quality of the grains.

Determination of chemical elements of barley and teff using flame atomic absorption spectroscopy (FAAS)

Metallic elemental analyses are needed to complete food composition databases, in which humans consume food to obtain energy and be able to do everyday work. The study aimed to investigate the concentrations of some metals (K, Al, Fe, Cu, Cd, and Pb) in teff and barley samples using flame atomic absorption spectroscopy (FAAS) techniques. The samples, weighing 0.5 grams each, were subjected to wet digestions using a mixture ratio of 7:3(vol/vol) of HNO3 to H2O2 reagents at 90°c for 3:00 h under optimal conditions. The reagents were used to digest food samples for the presence of specific metallic elements. Flame Atomic Absorption Spectroscopy (FAAS) was used to analyze the mineral contents of the digested samples. The results demonstrated that the relative concentrations obtained in these cereal crops are different from one another. The concentration of metallic elements in mg/kg of K (2709.6±3.3), Al (952.3±4.2), Fe (320.9±4.8), Cu (25.3±3.2), Pb (ND) and Cd (ND) for red teff, K (3053.7±1.6), Al (1095.2±4.2), Fe (271.6±4.8), Cu (60.1±3.2), Pb (ND) and Cd (ND) for white teff while K (4333.3±3.2), Al (2595.2±4.2), Fe (74.0±0.00), Cu (10.5±1.8), Pb (ND) and Cd (ND) for barley. The high content of potassium and aluminum metallic elements was found in barley cereals. The results of this study will be useful in enriching the database of Ethiopian cereals as foods, advancing the knowledge of cereals and deepening the scientific understanding of the cereals.

Assessment of harvest and postharvest losses of teff (Eragrostistef (Zucc.)) and methods of loss reduction: A review

Teff [Eragrostistef (Zucc.)] is one of the most important cereal crops in Ethiopia which is part of the traditional dish of the people in the form of Injera. Interest in Teff has increased noticeably due to its very attractive nutritional profile and the gluten-free nature of the grain. It is a gluten-free cereal, among the major cereal crops, Teff accounts for the largest average annual acreage in the country. It also accounts for the second-largest average annual production, next to maize. The study endeavored to review the harvest and postharvest losses, the causes of these losses, and possible solutions to reduce the postharvest losses of the Teff crop in Ethiopia. There are inadequate postharvest research works conducted in Ethiopia, and most of the limited studies are focused on cereals other than Teff. Teff farming in Ethiopia is dominated by traditional methods of harvesting and postharvest handling. The application of modernharvest and postharvest technologies during Teff production and handling is critically low. As a result, a considerable loss of Teffgrain (16-30 %) in the harvest and postharvest stages has been recorded. The largest share of this loss is observed during the harvesting stage due to shattering, scattering, animal feeding, and contamination with unwanted parts. Lack of awareness of postharvest losses, limited access and availability of postharvest technologies, and low attention given to postharvest research, extension, and infrastructure have also contributed their share to these losses. Transforming the traditional practice into mechanized farming, modern postharvest technologies, and supporting the system by further research works and pieces of training on loss prevention methods could potentially minimize the harvest and postharvest losses of Teff in the country.

Investigation of elemental composition in red teff grains using inductively coupled plasma optical emission spectroscopy (ICP OES), Sire District, Arsi zone, Ethiopia

BACKGROUND

Minerals are important not only for better plant growth and development but also for human and animal nutrition. It is known that east and west Gojam in the Amhara region and east and west Shoa areas in the Oromia region Ethiopia's most teff growing areas. However, there is no information on the mineral content and nutritional worth of Teff Sire district, Arsi zone, Ethiopia. Since ICP OES is a powerful technique to examine elemental compositions even in lower concentration, it is used in this work to investigate the elemental composition of red teff samples.

METHODS

The elemental compositions of red Teff grain samples were determined using ICP-OES from three sites: S1, S2, and S3 of Sire district, Arsi zone, Ethiopia. Wet digestion of the teff samples was carried out by weighing 0.5 g red teff sample and digested with 8 ml HNO3 and 2 ml H2O2 (30%) for 3:00 h at a temperature of 100℃ on hot plate. The investigations of method validation, limit of detection and limit of quantification were also carried out.

RESULTS

The average amount of elements in red teff sample obtained as 172-280 mg/kg Fe, 13-76 mg/kg Mn, 8.2-8.5 mg/kg Cu, 24-26 mg/kg Zn, and toxic trace elements 0.12-0.29 mg/kg Pb and 0.15-0.22 mg/kg Cd. The limit of detection found in ranges from 0.21 mg Kg-1 to 10.44 mg Kg-1 whereas quantification limit resulted in 0.7 mg Kg-1 to 34.8 mg Kg-1 for the metals under consideration. The method was validated by its linear range in the concentration range of 0.028-1.4 ppm or 0.056-2.8 ppm and excellent recovery result was achieved in the range of 90-120%.

CONCLUSION

This study aimed to investigate the mineral content in red teff cultivated in Ethiopia specifically Arsi zone by using ICP OES. From the obtained results, Iron was the first abundant essential element in red teff compared to Mn, Cu and Zn. The level of trace elements: Cd and Pb in the samples slightly above the acceptable limit, possibly due to agricultural practices like usage of fertilizers, pesticides, and other industrial products. Overall, this red teff elemental composition information contributes to the nutrition database and food safety in Ethiopia and beyond.

Metal(loid)s Profile of Four Traditional Ethiopian Teff Brands: Geographic Origin Discrimination

Among the most renowned Ethiopian food crops, teff (Eragrostis tef (Zucc.)Trotter) is the most nutritious and gluten-free cereal. Because of the increase in demand for teff, it is necessary to establish geographic origin authentication of traditional teff brands based on multi-element fingerprint. For this purpose, a total of 60 teff samples were analysed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Accuracy of the laboratory procedure was verified by the analysis of rice flour standard reference material (NIST SRM 1568b). In this context, four traditional teff brands (Ada'a, Ginchi, Gojam and Tulu Bolo) were analytically characterized using multi-element fingerprint and further treated statistically using linear discriminant analysis (LDA). Due to obvious extrinsic Fe, Al and V contamination, these elements were excluded from the discriminant model. Five elements (Cu, Mo, Se, Sr, and Zn) significantly contributed to discriminate the geographical origin of white teff. On the other hand, Mn, Mo, Se and Sr were used as discriminant variables for brown teff. LDA revealed 90 and 100% correct classifications for white and brown teff, respectively. Overall, multi-element fingerprint coupled with LDA can be considered a suitable tool for geographic origin discrimination of traditional teff brands.

Selenium in drinking water and cereal grains, and biomarkers of Se status in urine and fingernails of the Main Ethiopian Rift Valley population

BACKGROUND

Selenium (Se) plays an important role in human health, yet Se overexposure or deficiency can lead to deleterious health effects. This study aims to determine the concentration of Se in drinking water and staple cereal grain (maize, wheat, and teff) samples from the Main Ethiopian Rift (MER) Valley, and correspondingly, assesses Se biomarkers and their status as measured in the urine and fingernails of 230 individuals living in 25 MER communities.

METHOD

The concentration of Se in drinking water and cereal grain (maize, wheat, and teff) samples, and urine and fingernail samples were measured using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Demographic, anthropometric, and elemental concentrations were described by their quartiles and mean ± standard deviations. The 5th and 95th percentiles were used to describe the concentrations Se biomarkers ranges. The Se biomarker distributions in different study communities were further characterized according to Se levels found in drinking water, sex, and age using ANOVA, and multivariate regression. We conducted a correlation analysis (with Pearson correlation coefficient) and fitted a regression to evaluate the associations between these variables.

RESULTS

The mean concentration of Se in the drinking water samples was 0.66 (range: 0.015-2.64 µg/L; n = 25), and all samples were below the threshold value of 10 μg/L for Se in drinking water set by the World Health Organiation (WHO). In Ethiopia, most rural communities rely on locally produced cereal grains. We found mean Se concentrations (µg/kg) of 357 ± 190 (n = 14), 289 ± 123 (n = 14), and 145 ± 100 (n = 14) in wheat, teff, and maize, respectively. Furthermore, Se concentrations in drinking water showed no significant correlation with biomarker measures, indicating that the primary source of dietary Se is likely from local foods including staple grains. The mean±SD (5th-95th percentiles) of Se concentrations in fingernails and urine among study subjects were 1022 ± 320 (624-1551 µg/kg), and 38 ± 30 (1.9-100 µg/L), respectively.

CONCLUSION

A sizeable share of study participants (31%) fell below the lower limits of what is considered the currently accepted Se range of 20-90 µg/L in urine, though relatively few (only 4%) had similarly low fingernail levels. On the other hand, none of the samples reached Se toxicity levels, and the biomarker levels in this study are comparable to results from other studies that find adequate Se. Our results show that Se toxicity or deficiency is unlikely in the study population.

Multi-Element Assessment of Potentially Toxic and Essential Elements in New and Traditional Food Varieties in Sweden

With the global movement toward the consumption of a more sustainable diet that includes a higher proportion of plant-based foods, it is important to determine how such a change could alter the intake of cadmium and other elements, both essential and toxic. In this study, we report on the levels of a wide range of elements in foodstuffs that are both traditional and "new" to the Swedish market. The data were obtained using analytical methods providing very low detection limits and include market basket data for different food groups to provide the general levels in foods consumed in Sweden and to facilitate comparisons among traditional and "new" food items. This dataset could be used to estimate changes in nutritional intake as well as exposure associated with a change in diet. The concentrations of known toxic and essential elements are provided for all the food matrices studied. Moreover, the concentrations of less routinely analyzed elements are available in some matrices. Depending on the food variety, the dataset includes the concentrations of inorganic arsenic and up to 74 elements (Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cs, Cu, Fe, Ga, Ge, Hf, Hg, K, Li, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Rb, S, Sb, Sc, Se, Si, Sn, Sr, Ta, Te, Th, Ti, Tl, U, W, V, Y, Zn, Zr, rare Earth elements (REEs) (Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Tb, Tm, and Yb), platinum group elements (PGEs) (Ir, Os, Pd, Pr, Pt, Re, Rh, Ru, and Pr), and halogens (Br, Cl, and I)). The main focus (and thus the most detailed information on variation within a given food group) is on foods that are currently the largest contributors to dietary cadmium exposure in Sweden, such as pasta, rice, potato products, and different sorts of bread. Additionally, elemental concentrations in selected food varieties regarded as relatively new or "novel" to the Swedish market are provided, including teff flour, chia seeds, algae products, and gluten-free products.

Association studies of genes in a Pb response-associated network in maize (Zea mays L.) reveal that ZmPIP2;5 is involved in Pb tolerance

Lead (Pb) in the soil affects the growth and development of plants and causes damages to the human body through the food chain. Here, we identified and cloned a Pb-tolerance gene ZmPIP2;5 based on a weighted gene co-expression network analysis and gene-based association studies. We showed that ZmPIP2;5 encodes a plasma membrane aquaporin and positively regulated Pb tolerance and accumulation in Arabidopsis and yeast. Overexpression of ZmPIP2;5 increased root length and fresh weight of Arabidopsis seedlings under Pb stress. Heterologous expression of ZmPIP2;5 in yeast caused the enhanced growth speed under Pb treatment and Pb accumulation in yeast cells. A (T/A) SNP in the ZmPIP2;5 promoter affected the expression abundance of ZmPIP2;5 and thereby led to the difference in Pb tolerance among different maize lines. Our study helps to understand the mechanism underlying plant tolerance to Pb stress and provides new ideas for breeding Pb-tolerance maize varieties via molecular marker-assisted selection.

Okra (Abelmoschus esculentus) in a refugee context in East Africa: Kitchen gardening helps with mineral provision

Kitchen gardening is considered a way to reconnect with agriculture and complement the cereal-based relief food offered to refugees in East Africa. This work aimed at profiling mineral content of okra in four refugee camps and settlements located in Ethiopia and Uganda and its contribution to adequate intake (AIs) or recommended dietary allowances (RDAs) for young children and pregnant and lactating women (PLW). The study also evaluated the applicability of portable X-ray fluorescence (PXRF) as compared with inductively coupled plasma mass spectrometry (ICP-MS) for mineral profiling of okra powder samples. The contents of minerals (mg kg-1) from the ICP-MS readings were in the following ranges: K (14,385-33,294), Ca (2610-14,090), P (3178-13,248), Mg (3896-7986), Cu (3.81-19.3), Fe (75.7-1243), Zn (33-141) and Mn (23.1-261). Regardless of geographic origin, at low-end consumption probability (17 g day-1 for young children and 68 g day-1 for PLW), okra could contribute ˂ 15% (2.7-12.9%) AI for macro-minerals (K and Ca). In addition, the contributions to RDA values for Fe and Zn, elements of known public health interest, ranged from 4.5 to 34.7% for young children. Interestingly, regression lines revealed strong agreement between ICP-MS and PXRF readings for Mn and Zn, with R2 values > 0.91. This information is useful in support of nutrition-sensitive kitchen gardening programs through scaling culturally important crops in refugee settings.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s42452-021-04898-6.

Locally Adapted and Organically Grown Landrace and Ancient Spring Cereals-A Unique Source of Minerals in the Human Diet

Consumer interest in local and organic produce, sustainability along the production chain and food products contributing to health, are laying the foundation for local and organic-based diets using nutrient-dense food. Here, we evaluated 25 locally adapted landrace and ancient spring cereal genotypes per location over four locations and three years, for mineral content, nutritional yield and nutrient density. The results showed a large variation in minerals content and composition in the genotypes, but also over cultivation locations, cultivation years and for genotype groups. Highest minerals content was found in oats, while highest content of Zn and Fe was found in ancient wheats. The wheat Diamant brun, the wheat landrace Öland and naked barley showed high mineral values and high content of Zn and Fe when grown in Alnarp. Nutritional yield, of the cereals evaluated here, was high related to values reported internationally but lower than those found in a comparable winter wheat material. The nutrient density was generally high; less than 350 g was needed if any of the evaluated genotype groups were to be used in the daily diet to reach the recommended value of Zn and Fe, while if the suggested Novel Nordic Diet mix was used, only 250 g were needed. A transfer from currently consumed cereals to those in the present study, along the New Nordic Diet path, showed their potential to contribute as sustainable and nutrient-rich sources in the human diet.