Valorisation of immature cereal grains to improve food security in Sub-Saharan Africa: a case study on pepeta in Tanzania

Abstract

Cereals constitute an important proportion of the food supply for humans and animals. They are substantial sources of energy, protein, vitamins and minerals for the world population. 1 Cereals such as wheat, rice and maize, are known worldwide and form a major part of the diet in many countries. 2 In Sub-Saharan Africa (SSA), cereals represent the primary food in the tropical and semi-arid areas, 3,4 contributing up to 43% of the total household's food basket (Fig. 1.1) while accounting for 50% of the average daily caloric intake. 5 SSA is the origin and a major producer of sorghum (Sorghum bicolor), millets (Pennisetum spp.), teff (Eragrostis tef), fonio (Digitaria spp.) and African rice (Oryza glaberrima). 3 These cereals can combat the 'hidden hunger' caused by micronutrient deficiencies due to their high nutritional value. As gluten-free cereals, they have great potential to be formulated into a range of food and beverage products to aid people with celiac disease. 6 Beside their importance to food supplies and health, they can contribute to improved income among the most food-insecure population groups in African countries. 7 Fig. 1.1: Contribution of cereals and their products to the food basket in SSA Authors' calculations based on household food consumption data from *Belghith et al. 8 †South Africa Statistics 9and ‡ OECD/FAO 10 12 wheat consumption has been steadily increasing and is becoming an important food crop as a result of rapid population growth associated with increased urbanisation and changes in food preferences for precooked food such as bread, biscuits, pasta, noodles and porridge. 21,24 1.2 Nutritional value of cereals 1.2.1 Macronutrients Cereals are carbohydrate-rich foods; they contain about 75% carbohydrates, 1 as shown in Table 1.1. Starch, the major component of the cereal, occurs in the endosperm as granules of different sizes depending on cereal type (e.g., a diameter of 5 microns in rice and 25-40 microns in wheat) and shape (either large, lens-shaped granules or small, spherical granules).Amylose and amylopectin are the main components of the starch granule; their ratio varies depending on the cereal and its variety. 1,4 For instance, about 25-27% of amylose is present in nonwaxy cereals, while in waxy varieties starch is made up mostly of amylopectin. In some cereal products, there is a substantial amount of starch that is not digested and absorbed in the small intestine and can be functionally assimilated to dietary fibre (i.e., resistant starch). 25 Cereals contain low amounts of free sugars, mainly sucrose, up to 2%, and maltose, fructose, and glucose in small quantities. 1 Proteins in cereals range from 6 -15%, 26 with the type of stored protein differing among cereal types. For example, prolamins (gliadins and glutenins) are the major storage protein in wheat, albumins and globulins in oats, prolamins (hordeins) and glutelins in barley. At the same time, in rice, glutelin (oryzenin) is the most abundant storage protein, and maize has prolamin (zein). 27 Al...