Effect of teff plant nutrition on its functional food properties

Dr. Zipora Teitel
Start: Jun 2016 –  End: June 2018

Teff (Eragrostis tef) is an annual tropical Poaceae cereal, grown in a wide range of environments 1, and used throughout the world as grain for human consumption 2. There are few different varieties of teff, which vary in color from light to dark 2. Teff is indigenous to Ethiopia 3, where the grains are ground into flour, and further fermented into injera, a spongy and slightly sour flatbread 4. Teff is a staple food for majority of Ethiopians and millions of people in the semi-arid regions of the world 2.

The nutritional profile of teff indicates that it is rich in nutritionally important minerals such as iron, calcium, potassium and zinc 5-10 It is as nutritious as or better than the major western staple cereals such as wheat, rice, oats and barley, and is high in copper contents, as well as phosphorous and magnesium 11. Teff contains good levels of certain vitamins such as vitamin C, niacin, vitamin A, riboflavin and thiamin 1. It has an average of 10.4% protein, 2.3% crude fat and 3.3% crude fiber 1, 6, 12. Teff grains are rich in unsaturated fatty acids, including oleic acid and linoleic acid 13, which are essential fatty acids and possess health promoting effects, and it has an excellent amino acid composition (including all 8 essential amino acids for humans) 14. Teff is also a gluten free cereal 15, 16, high in dietary crude fiber 17, with a low glycemic index 18.

Certain minor components of foods are now recognized for their health promoting properties 19, due to the scientific agreement that they may help to lower the incidence of chronic diseases, including certain cancers, cardiovascular and neurodegenerative diseases, obesity, type-2 diabetes and hypertension 20-24. Foods containing these health-promoting components are termed “Functional Foods” 25.

Oxidative stress is associated with the pathogenesis of chronic diseases, and diets rich in natural antioxidants, such as polyphenols, have been suggested as beneficial 26, 27. Polyphenolic antioxidants play a very important role in the body defense system by scavenging reactive oxygen species, which are the harmful byproducts of normal cell metabolism 28-30. Bioactive polyphenols are present in fruits, vegetables, minimally processed whole grains and legumes, and include, among others, phenolic acids and flavonoids, which are responsible for the high antioxidant activity 31.

Teff is rich in several polyphenols, including the phenolic acids p-coumaric, ferulic, protocatechuic, gentisic, vanillic, syringic, caffeic, cinnamic and p-hydroxybenzoic, and the flavonoids apigenin, luteolin and quercetin 32-34. Of the three varieties, the highest antioxidative potential was observed in red teff, accompanied by highest phenolic and flavonoids contents 2. Teff extracts inhibited low-density lipoprotein oxidation and protected against oxidative DNA damage 34. Furthermore, incorporation of Teff flour into the breadmaking formulation showed significant improvements in iron content and total antioxidant capacity, and the researchers suggested that teff breads would contribute to a higher dietary intake of iron and antioxidants 3.

Ethiopian staple teff has a potential as a functional food and beverage for international health food market, due to its attractive nutritional profile, high calcium and fiber contents, its significant polyphenol levels and its gluten free property 11, 16. In developing countries the commercial processing of these locally grown grains into value-added food and beverage products can be an important driver for economic development 7.

The chemical composition of cereals varies widely and depends on the environmental conditions, soil, variety and fertilizer 7. Nevertheless, the effect of teff plant nutrition and fertilization on grain nutritional value has not been evaluated before, except for a two works, in which S and N fertilization increased S and N contents of the grains 35, 36.

Hypothesis, rational and aims

We hypothesize that

1. Plant nutrition treatments will affect the health promoting properties of teff grains.
2. Different teff varieties present different profiles of health-related compounds.
3. Growth area will affect the health-related compounds composition of teff grains.

Accordingly, research aims will be as follows:

1. To evaluate the effect of teff plant fertilization with different N/ P/ K regimes on the composition of teff phytochemicals. Such analysis will be informative in regard to the effects of plant nutrition on nutritional value of teff, and has not been reported before. Specifically, this analysis will be based on teff plant nutrition project carried out in Gilat Center.
2. To profile the content and composition of phytochemicals in different teff varieties. Specifically, this analysis will be based on samples of teff varieties grown in Rehovot campus.
3. To study the effect of growth area on teff nutritional composition. For this analysis, selected varieties from Rehovot campus would be likewise grown in Gilat Center.