Protein biofortified sorghum : effect of processing into traditional African foods on their protein quality

Protein biofortification into crops is a means to combat childhood protein-energy malnutrition (PEM) in developing countries, by increasing the bioavailability of protein in staple plant foods and ensuring sustainability of the crop. Protein biofortification of sorghum has been achieved by both chemically induced mutation and genetic engineering. For this biofortification to be effective, the improved protein quality in the grain must be retained when it is processed into staple African foods. Suppression of kafirin synthesis by genetic engineering appeared to be superior to improved protein digestibility by chemical mutagenesis, because both the lysine content and protein digestibility were substantially improved and maintained in a range of African foods. For the genetically engineered sorghums, the protein digestibility corrected amino acid score was almost twice that of their null controls and considerably higher than the high protein digestibility sorghum type. Such protein biofortified sorghum has considerable potential to alleviate PEM.The Bill and Melinda Gates Foundation, Grand Challenges in Global Health Initiative.http://pubs.acs.org/JAF

Do kafirin bioplastic materials have unique functional characteristics?

BACKGROUND AND OBJECTIVES : There is considerable interest in kafirin, sorghum prolamin, as a bioplastic material because it apparently produces bioplastics with superior functional properties. This review evaluates the evidence, focussing on research directly comparing the properties of kafirin bioplastics (films and elastomers) with those from zein and gluten. FINDINGS : Kafirin and zein are more hydrophobic than gluten but there is little difference in hydrophobicity between them. Kafirin and zein films have better moisture barrier properties than gluten films. Films made from total kafirin (α-, β-, and γ-kafirins) are stronger and take up less moisture than films from commercial zein (essentially α-zein). However, total kafirin- and total zein films have similar moisture uptake. Also, there is little difference in oxygen barrier properties between total kafirin- and commercial zein films. Total kafirin elastomers have better elastic recovery than commercial- and total zein elastomers and similar elastic recovery to gluten. CONCLUSIONS : The better functional properties of kafirin bioplastics compared to commercial zein bioplastics seems to be largely due to the greater disulfide bonded polymerization of kafirin polypeptides, involving the cysteine-rich β- and γ-kafirin classes. SIGNIFICANCE AND NOVELTY : This work should stimulate research into disulfide-bonded polymerization of prolamins to improve their bioplastic functionality.https://wileyonlinelibrary.com/journal/cchehj2024Consumer ScienceFood ScienceSDG-02:Zero Hunge

Cereal food technologies - India and Africa trends and the need for collaborative and networking programmes

India and Africa share many common food trends such as rapid urbanization and a growing demand for convenience and health-promoting foods.Notably in Africa, these food demands are currently being met by relatively simple value addition to grains through small and medium enterprises.However, achieving improved staple food security will require more complex technologies, higher technical skills and a better organized food pipeline. Thus, in Asia and Africa there is an acute need for collaborative and network programmes in grain science and technology. The recent creation of an ICC India Task Force to make India-International grain science collaboration and networking a reality is a critical step to achieving these goals.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1757-837

Roles of protein, starch and sugar in the texture of sorghum biscuits

This study investigated why biscuits made from sorghum flour have a similar texture to wheat biscuits despite the absence of gluten in sorghum dough. Electron microscopy revealed that the sorghum prolamin protein bodies remained intact in the sorghum biscuits and hence were unlikely to contribute to biscuit structure and texture. Polarized light microscopy showed that the starch granules in the sorghum biscuits were not gelatinized. Increasing dough water content increased the breaking strength and brittleness of sorghum biscuits. However, increasing the proportion of pre-gelatinized sorghum flour in the dough reduced the breaking strength of the sorghum biscuits, indicating that starch gelatinization weakened the biscuit structure. In contrast, increasing the sucrose content of the dough increased sorghum biscuit breaking strength and brittleness. At 20% sucrose (flour basis), the sorghum biscuits had similar breaking strength and brittleness to both Marie and sugar-snap wheat biscuits. DSC and X-ray diffractometry showed that the sugar in both the sorghum and wheat biscuits was in the glassy state and polarized light microscopy revealed that the sugar glass embedded or enveloped the sorghum biscuit flour particles. It is concluded that this sugar glass matrix is responsible for the strength and cohesiveness of the sorghum biscuits.The South African National Research Foundationhttp://www.elsevier.com/locate/lwthj2022Consumer ScienceFood Scienc

Cereal biofortification : strategies, challenges and benefits

Under-nutrition is a key underlying cause of the 10 million child deaths each year—most of which are preventable and most of which occur in poor countries. The major direct causes of under-nutrition in poor developing countries are insufficient food intake and an unbalanced diet caused by lack of variety in available foods coupled with disease outbreaks. This study shows that the majority of children living in rural Burkina Faso are severely undernourished as a result of the low amount of food they consume, their lack of dietary diversity, and, consequently, their low intake of many macro- and micronutrients. Replacement of normal cereal staples with biofortified crops would not affect the amount of food consumed per se. However, the strategy of most biofortification programs is to add nutrients to the most profitable and highest yielding varieties available, which would address, to some extent, the issue of insufficient food availability. For biofortified cereals to make a broad impact on the nutritional status of undernourished children in rural Africa, ideally the predominant cereals consumed should be enhanced with multiple critical nutrientsThe Bill and Melinda Gates Grand Challenges 9, Africa Biofortified Sorghum (ABS) Project through a sub-grant from the Africa Harvest Biotechnology Foundation International.http://www.aaccnet.org/publications/plexus/cfw/pastissues/2012/Pages/CFW-57-4-0165.asp

Protein quality and physical characteristics of Kisra (fermented sorghum pancake-like flatbread) made from tannin and non-tannin sorghum cultivars

Kisra is a naturally lactic acid bacteria- and yeast-fermented sorghum thin pancake-like flatbread produced in Sudan. Kisra has considerable potential as the basis for development of a gluten-free sandwich wrap. To help direct cultivar selection for commercial production of these products, two white, tan plant non-tannin Type I, one white Type II tannin, and one red Type III tannin sorghum cultivars were evaluated with respect to kisra protein quality and physical characteristics. Kisra from the non-tannin sorghums were flexible and had an open-textured structure with many regular gas cells, whereas those from the tannin sorghums were more brittle, denser in structure, and contained far fewer and smaller gas cells. Kisra from the tannin sorghums had the lowest reactive lysine content, in vitro protein digestibility, and Protein Digestibility Corrected Amino Score (PDCAAS), with values being lowest for the Type III sorghum. PDCAAS of kisra from the Type III sorghum was only 0.12, less than half of that from the Type I sorghums. As the tannins in tannin sorghums adversely affect kisra protein quality and physical characteristics, white tan plant, non-tannin sorghum cultivars are most suitable for kisra production and for development of wrap-type sorghum-based baked goods.The South African National Research Foundation for a fellowship for AMAE.http://cerealchemistry.aaccnet.or

Morphology, physical, chemical, and functional properties of starches from cereals, legumes, and tubers cultivated in Africa : a review

In Africa a variety of indigenous cereals, legumes, and tubers are cultivated as starchy food crops. These include sorghum, millet species including pearl millet, finger millet, teff, and white and black fonio, and African rice as cereals; cowpea, Bambara groundnut, African yambean and West African locust bean as legumes; and Zulu round potato and the Livingstone potato as tubers. Many of these plants are considered as “lost crops of Africa.” This paper critically reviews the literature on the physical, chemical, and functionality of their starches. Information is essentially limited to the native starches of sorghum, some millets, and cowpea. Livingstone potato starch information is essentially absent. Notable characteristics of African starches include that teff and finger millet have compound starch granules. Some of the starches have unique properties which could be valuable. The very small granular size of teff and its functional properties can be exploited as a fat replacer. The high retrogradation of cowpea starch has potential in gluten-free pasta and noodles. Nonfood applications for the African starches should be considered in the growing mining and oil industries in Africa.http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1521-379Xhttp://www.starch-journal.comhj201

Effects of processing sorghum and millets on their phenolic phytochemicals and the implications of this to the health-enhancing properties of sorghum and millet food and beverage products

Sorghum and millet grains are generally rich in phytochemicals, particularly various types of phenolics. However, the types and amounts vary greatly between and within species. The food processing operations applied to these grains: dehulling and decortication, malting, fermentation and thermal processing dramatically affect the quantity of phenolics present, most generally reducing them. Thus, the levels of phytochemicals in sorghum and millet foods and beverages are usually considerably lower than in the grains. Notwithstanding this, there is considerable evidence that sorghum and millet foods and beverages have important functional and health- promoting effects, specifically antidiabetic, cardiovascular disease and cancer prevention due to the actions of these phytochemicals. Also their lactic acid bacteria fermented products may have probiotic effects related to their unique microflora. However, direct proof of these health-enhancing effects is lacking as most studies have been carried out on the grains or grain extracts and not the food and beverage products themselves, and also most research work has been in vitro or ex vivo and not in vivo. To provide the required evidence, better designed studies are needed. The sorghum and millet products should be fully characterised, especially their phytochemical composition. Most importantly, well-controlled human clinical studies and intervention trials are required.http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1097-00102016-01-31hb201

Role of γ-kafirin in the formation and organization of kafirin microstructures

The possible importance of the cysteine-rich γ-prolamin in kafirin and zein functionality has been neglected. The role of γ-kafirin in organized microstructures was investigated in microparticles. Residual kafirin (total kafirin minus γ-kafirin) “microparticles” were non-discrete (amorphous mass of material), as viewed by electron microscopy and atomic force microscopy. Adding 15% γ-kafirin to residual kafirin resulted in the formation of a mixture of non-discrete material and nanosize discrete spherical structures. Adding 30% γ-kafirin to the residual kafirin resulted in discrete spherical nanosize particles. Fourier transform infrared spectroscopy indicated that γ-kafirin had a mixture of random-coil and β-sheet conformations, in contrast to total kafirin, which is mainly α-helical conformation. γ-Kafirin also had a very high glass transition temperature (Tg) (≈270 °C). The conformation and high Tg of γ-kafirin probably confer structural stability to kafirin microstructures. Because of its ability to form disulfide cross-links, γ-kafirin appears to be essential to form and stabilize organized microstructures.Joseph Anyango is grateful for the provision of a University of Pretoria Postdoctoral Fellowship.http://pubs.acs.org/journal/jafcauhb201

Improvement in water stability and other related functional properties of thin cast kafirin protein films

Improvement in the water stability and other related functional properties of thin (<50 µm) karirin protein films was investigated. Thin conventional kafirin films and kafirin microparticle films were prepared by casting in acetic acid solution. Thin kafirin films cast from microparticles were more stable in water than conventional cast kafirin films. Treatment of kafirin microparticles with heat and transglutaminase resulted in slightly thicker films with reduced tensile strength. In contrast, glutaraldehyde treatment resulted in up to a 43% increase in film tensile strength. The films prepared from microparticles treated with glutaraldehyde treatment were quite stable in ambient temperature water, despite the loss of plasticizer. This was probably due to the formation of convalent crosslinking between free amino groups if the kafirin polypeptides and carbonyl groups of the aldehyde. Thus, such thin glutaraldehyde-treated kafirin microparticle films appear to have good potential for use as biomaterials in aqueous applications.J.O.A. acknowledges a University of Pretoria Postgraduate Research Support Bursary.http://pubs.acs.org/JAF