**3. Postharvest losses situation in Africa**

*Recent Advances in Rice Research*

sustainable rice postharvest system in Africa.

economic value and competitiveness of milled rice.

*Unit operations at different levels of rice postharvest system in Africa.*

in Africa through the development of technologies for utilization of broken rice fractions and rice husk to reduce rice postharvest losses in Africa. Major challenges mitigating the adoption of this technologies and possible opportunities in the rice postharvest value chain that can attract investment for the improvement of rice production and reduction in rice postharvest losses are also outlined. This synthesis we believe will help in providing future direction for research and support for

Rice postharvest value chain is a set of unit operations in which well matured harvested paddy rice pass through from the point of harvest to consumption. Efficient and sustainable rice postharvest value chain therefore, aimed at minimizing losses and maximizes quality of the harvested grains until it reaches the consumer [10]. At each level of the value chain, several actors are involved and different values of losses are recorded. In Africa, especially in West Africa, several actors using diverse kinds of equipment and techniques are involved in primary, secondary and tertiary postharvest operations of the rice value chain (**Figure 1**). Losses particularly along the value chain [1–18] has been highlighted as a major source of lost in revenue and productivity among value chain actors as both quantitative and qualitative losses occur during any of the stages [19]. This is an indication that critical attention need to be given to the postharvest value chain to reduce loss in productivity and make rice production a sustainable venture. Technically, when paddy is harvested, it passes through the first routes (A), before storage, but may also be traded directly by farmers to middle men or collected together by farmers' cooperative groups where this exists before marketing at a favourable period. Currently in Africa, especially SSA, little or no value addition is carried out at the primary postharvest level. At the second level (B), some levels of value addition are made where the paddy is either milled after parboiling or directly after winnowing to produce white rice which is traded as milled rice and used for the preparation of traditional whole kernel rice-based foods [20]. At this point where appropriate technologies are used, grain quality is improved which translate into improved

Over the last few years, in Nigeria and other African countries, several large scale integrated mills have been installed which combined parboiling and milling operations and coupled with grading and packaging system. In these mills, parboiling and drying energy are generated by combusting the husks, while milling uses electricity from national grid or private generators. Recently, a third level have been added to the chain, where low grade broken fractions, a by-product of rice milling is converted to rice flour and used for the production of diverse rice-based products (C) or other by-products such as husk are used for energy for artisanal rice parboiling and household cooking [16, 17, 21]. The tertiary postharvest level is built on broken rice, bran

**2. Understanding the rice postharvest value-chain in Africa**

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**Figure 1.**

Postharvest losses in food production including rice not only have effects on social and economic scales, but also represent a waste of resources used in production such as land, water, energy and other inputs. Report by Africa Postharvest Loss Information System [22] indicated that losses occurs hugely at all levels of the rice postharvest operations. Harvesting operations including harvesting, threshing, winnowing and drying resulted in an average of 11.2% loss due to grain spillage and poor threshing where grains are left on panicles. Transportation resulted in 2.3% (to farm and market) and storage 3.4% indicating an approximately 15.91% average postharvest loss across the continent. Report by Sallah, [23] on the postharvest losses of rice and its implication on livelihood and food security in Africa taking a case of Cameroon and The Gambia indicated that losses at threshing operation were 19 and 17%, drying 9.3 and 7.0%, storage 4.2 and 6.0%, milling 1.3 and 1.0% and transportation 1.33 and 0.8% respectively for Cameroon and The Gambia. This results in reduced income and employability of the people in the study area. Loss was aggravated by lack of or poor processing equipment, poor storage facilities, poor knowledge and skills on postharvest reduction strategies.

It has been estimated in Nigeria by Oguntade *et al*., [24] that rice post-harvest losses may be as high as 20 to 40%, implying conservatively between 10 and 40% of rice that grown in the country never reaches the market or consumers table or are traded at a discounted price due to loss of quality resulting from poor postharvest management. The high postharvest losses slowdown the marginal increase in rice production recorded over the last few years in many African countries and also threatened food and nutrition security. Because of the adoption of improved technology in rice production in developed countries, postharvest losses occur primarily at the consumer level, with minimal losses at the field or after harvesting or at the other stages of the value chain [10, 25]. In contrast, postharvest losses in Africa occur mainly during harvesting through to market stages, with slightest share of losses occurring at the consumption level [25, 26].

According to Oguntade *et al*. [24], huge losses totalling about 11.39% is recorded during rice postharvest level in Nigeria, with harvesting accounting for 4.43%, threshing and cleaning (4.97%), transporting paddy from field to homes (0.34%), paddy drying and storage (1.53%) and transporting of paddy to local markets (0.12%). At secondary postharvest levels (**Figure 1**), rice parboiling process, an essential pre-treatment given to paddy rice before milling accounted for 5.19% paddy loss, while milling at the village level and milled rice transportation, marketing and storage results in 4.40% and 7.54% losses respectively. Danbaba *et al*., [10] correlated the data with rice production statistics of 17.5 MMT of paddy produced in Nigeria in 2016 [27], considering postharvest losses of 11.39% paddy from harvest to market and 135 Naira per Kg market price of paddy (as at November, 2018), Nigeria losses about 1.99 MMT of paddy representing 269.09 billion naira annually. These losses are huge and unsustainable if added up to the estimated 123 billion naira losses during the parboiling and milling processes. Situations from the three African countries classically indicates the unfavourable postharvest loss situation on the continent which calls for urgent action and intervention.
