ReviewChemical composition and food uses of teff (Eragrostis tef)
Introduction
Teff [Eragrostis tef (Zucc.) Trotter] is an annual crop in the Poaceae (grass) family (Bultosa, 2016). Teff is also commonly written as tef. In this review, teff is used to follow the nomenclature of Encyclopedia of Food Grains (Bultosa, 2016). It is a major food crop native to Ethiopia and Eritrea for the production of a range of traditional foods/beverages such as injera (flatbread), kitta (unleavened bread), and tella (opaque beer) (Bultosa, 2016, Gebremariam et al., 2014). The production of teff in Ethiopia reached 4.2 million tonnes in 2015 (Ethiopian Agricultural Transformation Agency, 2016). Teff is adapted to a range of growing environmental conditions such as drought and water-logging (Assefa et al., 2015). It can thrive at some harsh climate conditions when major crops may fail (Assefa et al., 2015). Furthermore, during storage, teff is much less susceptible to the attacks by weevils and other pests than common grains (Gebremariam et al., 2014). Therefore, it plays an important role in food security in eastern Africa and in combating the global climate change. Like sorghum and maize, teff is a C4 plant which utilizes CO2 very efficiently during photosynthesis. Ethiopia is the centre for teff genetic diversity. The Ethiopian genetic pool holds a great promise to further improve the agronomic traits of teff (Assefa et al., 2015, Bultosa, 2016).
In recent years, teff is gaining popularity around the world mostly due to its attractive nutritional properties (Gebremariam et al., 2014). Its cultivation has been successfully adapted to other parts of the world such as USA, India, and Australia (Wikipedia., 2017). Teff grain is gluten free and has great potential to be formulated into a range of food/beverage products to aid people with celiac disease (Gebremariam et al., 2014). Teff flour is of whole grain because of the very small grain size. So the flour is rich in fiber due to the incorporate of the bran components. It is also a source of bioactive compounds such as polyphenols (Shumoy & Raes, 2016). As a result of the unique chemical composition and the whole grain form, a range of health benefits have been associated with teff. For example, teff showed in vitro anti-oxidative activities, and can improve the haemoglobin level in human body and help to prevent malaria, and incidence of anaemia and diabetes (Gebremariam et al., 2014, Salawu et al., 2014). Because of such health effects and attractive nutrients, many efforts have been made in the laboratories to produce teff-based food/beverage products in recent years (Gebremariam et al., 2015, Giuberti et al., 2016). Apart from the grain for food uses, teff straw can be used as a feed for horse and oxen (McCown et al., 2012, Mengistu, 2003). The straw can be treated for biomethane production and may be used as an adsorbent of Cr(VI) in contaminated waste waters (Chufo et al., 2015, Tadesse et al., 2015). Therefore, comprehensive and green utilization of teff without generating much waste is possible.
A previous review summarised the composition and utilization of teff from the literatures up to the year 2011 (Gebremariam et al., 2014). In the past few years, because of the rise of global healthy food market as well as the active cultivation of teff outside Eastern Africa, there have been a lot of research activities on teff. The mini-review updates the current advances in the genetic diversity, chemical composition, and various food/beverage uses (on the laboratory or pilot research scale) of teff grain. This review provides a scientific basis to further develop this under-utilised species as a sustainable crop.
Section snippets
Genetic diversity
Compared with the majority of cereals, teff is more tolerate to harsh conditions such as water-logging and poorly drained vertisols (Assefa et al., 2015). The grain has exceptional storability and is relatively resistant to pest attacks during storage (Assefa et al., 2015). However, the productivity of teff tends to be rather low (e.g., 1.5 t/ha). There is a lack of cultivars that have great tolerance to drought, lodging, and pests (Assefa et al., 2015). Furthermore, teff variety may greatly
Chemical composition
The chemical composition of teff grain has been much studied in recent years (Table 1 & Supplementary Table 1). Overall, the new results agree with the previous reports as summarised by Gebremariam et al. (2014), though new findings have continued to expand the knowledge of teff composition as described in the following sections. It should be pointed out that Table 1 and supplementary Table 1 presented the composition of grains of only 1 teff variety.
Food uses
Teff flour has been incorporated into a range of food products, especially the gluten free products (Table 2). Teff addition in wheat based foods positively influences the nutritional properties of these products. The changes in the quality attributes of food products due to teff addition have been monitored. Because of the lack of gluten-type protein, teff may negatively impact on the product quality, and various techniques/additives have been employed to encounter such changes. Some of the
Conclusions and future research directions
Teff is becoming popular in healthy food markets of developed countries in terms of production and consumption. A lot of research had been conducted on teff during the last decade. For food security, teff may be suitable for cultivation in places of harsh climate and environments in developing countries such as China and India. Major findings on teff composition and uses from the recent reports include, but not limited to, the followings:
Genetic diversity of teff in a range of agronomic traits
Declaration
The author declares no conflicts of interest.
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