**5.2 Development of ready-to-eat (RTE) high protein extruded snacks and porridges from broken rice fractions**

Recent changes in social life of many population across the world and the development of middle class worker in developing countries of Africa has resulted in high population of people who are inclined to eat 'ready-to-eat' food, because of its convenience, easy to consume, low to moderate price with minimal need for further processing. Extruded snacks are example of such products and their consumption is growing by day. Extrusion cooking technology is a continuous mixing, cooking and shaping process carried out at high temperatures over short times [41]. It is a very versatile, low-cost and highly energy efficient technology for snack or expanded foods production. Extrusion of cereal-based flours or other starchy raw materials is widely used in the food industry in developed countries to produce snack foods [42]. Little of extrusion cooking is being practiced in Africa especially as it relates to value added rice processing, but recent advances in rice postharvest science has introduce the use of low grade broken rice fractions as raw material for the production of extruded snack foods [10, 43].

However, when starchy raw materials such as rice are subjected to extrusion cooking, there is a chemical and structural transformation such as starch gelatinization, protein denaturation, complex formation between amylose, lipids and/or proteins, and degradation of pigments and vitamins [44]. Under the Africa-Wide Taskforce on Rice Processing and Value Addition of Africa Rice Centre and its national partners, low grade broken rice fractions from different milling operations have been tested and validated for the production of snacks that are high in protein and acceptable to consumers [21, 43]. Through process modelling and optimization, optimum moisture content, barrel temperature and level of legume flour for extrusion have been established for the blends of broken rice fractions with cowpea, bambara groundnut and soybean, keeping other extrusion parameters within range [21, 28, 43]. This optimized process conditions produces extruded snacks with smooth outer-surface (**Figure 4**) and uniform air spaces with regular shape, this according Ryu et al., [45] are features of good quality extrudates.

Because extrusion cooking process allows for the production of low-fat snacks and induces the formation of resistant starch, which makes no caloric contribution

#### **Figure 4.** *Photographic images (longitudinal section) of the physical state of rice-cowpea blend extruded snacks.*

*Recent Advances in Rice Research*

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**Figure 3.**

**Figure 2.**

*High quality rice flour from broken rice fractions (left), branded rice flour (centre) and rice flour blended with* 

*Flow chart for the production of high quality rice flour from broken rice fractions. Danbaba et al. [21].*

*cowpea flour for the production of high protein baked products [21].*

and behaves physiologically like dietary fibre [46], rice-based extruded snacks in Africa have received satisfactory acceptability among consumers that are concerned with nutritional quality of food they eat. As a result, therefore, the application of extrusion cooking is increasingly becoming popular for snack production in Africa using raw materials such as rice [28, 43], sorghum [47], and millet [48] containing protein, starch and dietary fibre in an effort to create novel food products such as snacks with a more adequate nutritional value. This new product is expected to improve rice postharvest system through qualitative loss reduction and improve overall food and nutrition security of the populace.

In some instance, it has been demonstrated that when crushed and pulverized, extruded broken rice fractions could be used as porridge or weaning foods. Danbaba *et al* [21, 28] introduced extruded ready-to-eat rice porridge (**Figure 5**) as part of valorisation of low quality broken rice fractions after blending with appropriate amount of legume flour. Protein-energy malnutrition (PEM) and micronutrient deficiency is a severe problem facing developing countries and particularly children

**Figure 5.** *Production of extruded high protein-energy weaning porridge from blends of broken rice and cowpea.*

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**Figure 6.**

*Advances in Rice Postharvest Loss Reduction Strategies in Africa through Low Grade Broken Rice…*

under the age of 5 years. This has resulted in more than 50% of childhood death in developing countries including Africa [49, 50]. Blending cereals with legumes in the production of complementary foods has been shown to improve childhood nutrition and significantly reduce mortality [21, 28, 43]. Several authors including Stojceska *et al*., [51]; Obradović *et al*., [52]; Panak Balentić *et al*., [53, 54] have also shown in other parts of the world that it is possible to enrich extruded cereal-based snacks with nutritionally valuable ingredients such as protein from ingredients like legumes. The utilization and application of extrusion cooking in Africa provides an alternative for producing high protein-energy weaning porridges from the blends of low grade broken rice and legumes. This process according to Pathania, *et al*., [55] credible alternative from the traditional practices for the manufacturing of re-constitutable foods for blended flours (**Figure 5**). Extrusion cooking therefore is expected to impact positively on the rice postharvest system in Africa in the years to come.

The increased demand by more consumers for gluten-free products has over the few decades necessitated the quest for suitable alternative raw materials to wheat for the production of third-generation snacks, and the use of rice flour is gaining greater interest because of its favourable attributes of negligible gluten content, good expansion during extrusion and bland taste [56]. Third-generation snacks (3G), also called semi or half products, during production undergo cooking after extrusion and are dried to a stable moisture content (approximately 12%) and then expanded by frying in hot oil, puffing in hot air or microwaving and infrared heating as new variants [57]. In developed world or where extrusion cooking technology has gained popularity, 3G snacks are common. After expansion products are spiced with various types of spices and then packaged and sold as ready-to-eat (RTE) snacks [57]. The products can also be flavoured before expansion and sold as pellets, for preparation at home [58]. In Nigeria, under a strategy to improve postharvest quality of rice, especially poor quality rice varieties having poor parboiling characteristics, kernels are converted to high quality flour of specific particle size and used innovatively for the production of 3G snacks (**Figure 6**) that are current popular

*DOI: http://dx.doi.org/10.5772/intechopen.94273*

**5.3 Development of third-generation snacks**

among snack producers in many African countries [21].

*Some rice-based 3G snacks produced from low grade broken rice flour.*

#### *Advances in Rice Postharvest Loss Reduction Strategies in Africa through Low Grade Broken Rice… DOI: http://dx.doi.org/10.5772/intechopen.94273*

under the age of 5 years. This has resulted in more than 50% of childhood death in developing countries including Africa [49, 50]. Blending cereals with legumes in the production of complementary foods has been shown to improve childhood nutrition and significantly reduce mortality [21, 28, 43]. Several authors including Stojceska *et al*., [51]; Obradović *et al*., [52]; Panak Balentić *et al*., [53, 54] have also shown in other parts of the world that it is possible to enrich extruded cereal-based snacks with nutritionally valuable ingredients such as protein from ingredients like legumes. The utilization and application of extrusion cooking in Africa provides an alternative for producing high protein-energy weaning porridges from the blends of low grade broken rice and legumes. This process according to Pathania, *et al*., [55] credible alternative from the traditional practices for the manufacturing of re-constitutable foods for blended flours (**Figure 5**). Extrusion cooking therefore is expected to impact positively on the rice postharvest system in Africa in the years to come.
