Chapter 9.7

9.7 - Small grains for mineral nutrition

Nick Moroz, University of Guelph, Canada

Suggested citation for this chapter.

Moroz,N. (2022)Small grains for mineral nutrition, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org

Small Whole Grains have High Mineral and Nutrient Content

This chapter is meant to inform subsistence farmers as well as governmental, and non-governmental organizations (NGOs) about the advantages of small grains as a source of high-quality nutrition. Small grains maximize surface area of the seed coat – the part of the seedling with the highest mineral density – and have the unique ability to keep for long periods of time. This chapter will outline the benefits of consuming small grain cereals as well as small grain legumes (pulses) and provide a critical analysis of these grains to ensure quality and proper knowledge transfer. Because of the advantages of small grains, the main point of this chapter is that these grains should be promoted.

Consumption of any small whole-grain is advantageous, whether it is a small whole cereal grain or the pulses (small dried seed-grains) of legume crops. There is a diversity of nutritional small grains, including lentils (a pulse), sorghum, quinoa, teff, fonio, and many more. Both cereal grains and pulses are high in minerals, energy, protein, and other nutritional factors. This chapter will outline small whole grains cereals followed by an outline of small whole grain pulses with a further analysis of their advantages. This is followed by a critical analysis at the end of this chapter.

Small Whole Grains and Whole-Grain Cereals

Whole-grains cereals are rich in many nutrients, condensed within their endosperm, germ and protective bran (the coating of the grain) (Slavin, 2004). All three components – endosperm, germ, and bran - are preserved and eaten in whole grains (Slavin, 2004). This is in contrast to refined-grains, whose embryo and protective components (the bran) are removed in processing, leaving only the endosperm (Slavin, 2004). Refined-grains generally have lower nutritional content compared to whole-grains, as it is the grain coat of whole grains that supplies the most concentrated source of minerals and beneficial phytochemicals (Dayakar et al., 2016; Slavin, 2004). These seed-coat nutrients are what are needed in addressing malnutrition. Although the refining of grains typically removes the grain seed coat and reduces nutritional content, small whole grains (such as Finger Millets) are generally eaten whole, providing a more nutritious meal to the consumer (Slavin, 2004; Tripathi & Platel, 2010). This is the key advantage of small whole grains in addressing micronutrient deficiencies compared to other refined grains.

Millet grains are small-seeded whole grains that have high nutritional quality and can provide numerous health benefits (Saleh, Zhang, Chen, & Shen, 2013; Krishnan, Dharmaraj, & Malleshi, 2012; Slavin, 2004). Millet grains are important in many developing countries due to their suitability as a sustainable staple crop in regions throughout Africa and Southern Asia (Saleh et al., 2013). There are many different millets species and varieties, including the very important Pearl Millet (Pennisetum glaucum) and Finger Millet (Eleusine coracana) (Saleh et al., 2013). The last world total production tally of millet grains saw an annual production of 762712 metric tons, making it the sixth cereal crop in terms of world production, with the top producer India creating 43.85% of this total (Saleh et al., 2013). One example of the utility of millet grains is seen in the nutritional and livelihood security they provide in dry rural regions of India due to their drought-resistance and high temperature tolerance (Saleh et al., 2013).

Finger Millet is an especially notable source of many minerals, containing high amounts of iron and zinc, as well the richest source of calcium among the cereals (Krishnan et al., 2012). It’s overall mineral content is 2.7%, distinctly higher than 1.5% mineral content in wheat and 0.6% mineral content in rice (Krishnan et al., 2012). Data outlining the nutrition benefits of finger millet and other small whole-grain cereals can be seen in table 1.1 and 1.2. Millet crops are generally as high or higher in protein and carbohydrate nutrition as maize, rice, and wheat (Saleh et al., 2013). Due to this high nutritional content and drought-resistance, Finger Millets can be used for combating micronutrient deficiencies in more arid regions (Krishnan et al., 2012).

Tables 1.1 and 1.2 include an extensive amount on information comparing millets as well as refined grains to show that their nutritional values of energy, carbohydrates and proteins are variable but somewhat similar. However, table 1.2 also shows that millets can have much higher essential mineral content than refined grains (rice and wheat) and are seemingly more nutritious than rice

Another advantage of millet grains is that they represent a cheaper option in comparison to the cereals, explaining why they are staple crops in many poorer parts of Southern Asia and Africa (Tripathi & Platel, 2010). As mentioned, millet grains also remain more productive under arid conditions than cereals (Saleh et al., 2013). Drought-tolerant millet grains can provide high mineral and nutritional contents that can benefit human nutrition while providing food security in a sustainable and reliable way (Saleh et al., 2013).

Small Grain Pulses have High Protein and Mineral Content

Pulses are the small grains of legumes. Legumes are unique plants in that they can fix nitrogen through a symbiotic relationship, ultimately resulting in higher protein content compared to other crops. Because pulses contain a seed coat similar to whole-grain cereals, pulses are also very high in mineral content. More information on legumes and pulses can be found at in this encyclopedia under the title: Legumes & Pulses to Reduce Protein and Mineral Deficiencies

Tables 1.3 and 1.4 include information that shows how diverse and advantageous legumes are for nutrition. Legumes are high in energy, protein, and very high in many minerals, as seen in these two tables. Some legumes (i.e. peanuts) can be very high in fats as well.

Supplementation and Fortification Interventions using Small Whole Grains

A possible intervention to improve nutritional health is to fortify millets (or millet flours) with mineral supplements. This could help address the malnutrition in sub-Saharan Africa and Southern Asia, as millets are staple crops in these regions due to their drought-resistant properties (Tripathi & Platel, 2010). In fact, one study done at the Central Food Technological Research Institute (CSIR) in India found that Finger Millet (Eleucine coracana) flour could effectively be used as a vehicle for zinc fortification (Tripathi & Platel, 2010). Further research should be done to assess if similar results can be achieved with other micronutrients, such as the essential vitamins and minerals outlined in the Human Nutrition chapters of this encyclopedia. Millets crops are cheaper in comparison to cereals crops, and thus are used by many populations in poverty (Tripathi & Platel, 2010). As such, fortifying millets with vitamin and mineral supplements could help numerous people living below the poverty line.

Finally, addressing nutrient deficiencies through bio-fortification by genetically engineering crops to produce higher concentrations of vitamins and minerals could be a solution in areas where the infrastructure for supplementation or food fortification is not possible (Basset et al., 2005; Nestel, Bouis, Meenakshi, & Pfeiffer, 2006). It could also reduce the costs of food fortification each year.

Critical Analysis of Small Whole Grains

Although millet grains are highly beneficial for nutrition, the conditions in which they are consumed are important. One study showed that the treatment of millets in cooking and preparing could greatly decrease the total micronutrient levels, but also increase the bio-accessibility of calcium, iron, and zinc in finger millet (Krishnan et al., 2012). For example, the study shows that native Finger Millet had total iron levels of 13.1 mg/100g before any treatment, whereas once the millet was expanded its iron concentration lowered to 5.5 mg/100g (Krishnan et al., 2012). However, under the same treatment conditions, the Finger Millet showed the bio-accessibility of iron goes from 1.16 to 2.7 mg/ 100g (Krishnan et al., 2012). It should be noted from this that the treatment of millet grains could influence the bio-accessibility of the rich micronutrient content housed within these crops.

Beneficial Seeds and Nuts in Africa

Africa is home to a wide variety of seeds and nuts that are highly concentrated in minerals and nutrients. Local varieties of crops should be explored to help address mineral deficiencies in rural regions. Egusi is a melon-like crop that is part of the watermelon family and is known for its large white seeds (NRC, 2006). Indeed, these seeds are used in a variety of meals through West Africa (NRC, 2006). Often the seed coat is removed and the seeds are then eaten or crushed into a powder and added to soups (NRC, 2006). Through the use of highly mineral-concentrated seeds from different melons, including the various varieties of Egusi grown throughout Africa, heightened intake of micronutrients could be achieved in rural and remote regions. For more information, readers are directed to the “Lost Crops of Africa” (NRC, 2006).

Picture Based Lesson to Train Farmers

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References

1. Basset, G. J., Quinlivan, E. P., Gregory, J. F., & Hanson, A. D. (2005). Folate synthesis and metabolism in plants and prospects for biofortification. Crop Science, 45(2), 449-453.

2. Dayakar Rao B, Bhaskarachary K, Rajendra Prasad M.P, Bala Krishna D, Dhanasri K, Nageswara Rao T.G. (2016). Nutritional and Health Benefits of Millets. ICAR- Indian Institute of Millets Research, Rajendranagar, Hyderabad, pp 86.

3. FAO/WHO, Joint (2002). Human vitamin and mineral requirements. Chapter 7. Rome, Food and Agriculture Organization of the United Nations and World Health Organization.

4. Krishnan, R., Dharmaraj, U., & Malleshi, N. G. (2012). Influence of decortication, popping and malting on bioaccessibility of calcium, iron and zinc in finger millet. LWT-Food Science and Technology, 48(2), 169-174.

5. Nestel, P., Bouis, H. E., Meenakshi, J. V., & Pfeiffer, W. (2006). Biofortification of staple food crops. The Journal of nutrition, 136(4), 1064-1067.

6. NRC, National Research Council. (2006). Lost Crops of Africa: Volume II: Vegetables. National Academy of Sciences. Washington, DC, USA.

7. Saleh, A. S., Zhang, Q., Chen, J., & Shen, Q. (2013). Millet grains: nutritional quality, processing, and potential health benefits. Comprehensive Reviews in Food Science and Food Safety, 12(3), 281-295.

8. Slavin, J. (2004). Whole grains and human health. Nutrition research reviews, 17(01), 99-110.

9. Tripathi, B., & Platel, K. (2010). Finger millet (Eleucine coracana) flour as a vehicle for fortification with zinc. Journal of Trace Elements in Medicine and Biology, 24(1), 46-51.

10. USDA (United States Department of Agriculture), 2017. USDA Food Composition Databases. Retrieved from: https://ndb.nal.usda.gov/ndb/nutrients/report/nutrientsfrm?max=25&offset=0&totCount=0&nutrient1=417&nutrient2=&nutrient3=&subset=0&sort=c&measureby=g

11. USDA (United States Department of Agriculture), 2017. USDA Food Composition Databases. Full Reports.