This article is an edited excerpt from the 2022 Regional Strategic Analysis and Knowledge Support System (ReSAKSS) Annual Trends and Outlook Report.
There is increasing interest in traditional African vegetables – including spider plant, amaranth, African nightshade, African eggplant, jute mallow, cowpea leaves, slenderleaf, sweet potato leaves, and pumpkin – particularly among wealthier consumers in cities.
Kenya and Tanzania are uniquely placed to take advantage of the domestic and regional markets expanding through their ports and centralised locations. There is great potential to increase the production and processing of these plants in Kenya and Tanzania, which could improve the use of vegetable processing units. More than 90% of agricultural produce in the two countries is sold unprocessed. Value added in traditional African vegetables remains largely untapped, though it is key to remember that from a nutritional point of view, they are best eaten fresh with minimal processing.
In Tanzania, amaranth and sweet potato leaves are the most popular, while in Kenya, the most popular are cowpea and African nightshade leaves. These vegetables are both resilient and nutritious, and have received much interest among health-conscious urban consumers. Traditional African vegetables also have the potential to improve environmental sustainability by contributing to agrobiodiversity and strengthening climate resilience among farmers. They are generally better adapted to local growing conditions and require fewer external inputs than exotic fruits and vegetables like pineapples and tomatoes, which are usually produced in monocrop systems. However, the production of traditional African vegetables can be highly seasonal, and market prices fluctuate greatly.
Processing can reduce such price fluctuations while increasing overall supplies and adding value for smallholder farmers and traders. There is a tradition of processing traditional African vegetables in East Africa, but the share that is processed is currently small. It is estimated that 2.1% of Kenyan farmers and 14.5% of intermediaries process these plants. Basic processing carried out by farmers and traders includes washing, plucking the leaves from the stalks (destalking), chopping, grading and sorting, and blanching. Over 88% of consumers in Kenya are willing to pay more for cleaned, sorted, and graded fresh cowpea leaves, while 35% and 25% of consumers, respectively, prefer destalked and chopped vegetables over unprocessed vegetables. The use of open-air sun drying is also common across Africa south of the Sahara, as is drying in the shade using passive or active air circulation. More recently, solar dryers have been introduced to dry vegetables more efficiently and consistently than shade drying.
More advanced methods of processing can include cooling, fermentation, freezing, and processing into powdered vegetables. Cooling and refrigeration are currently applied only in supermarket value chains. Fermentation using lactic acid is practiced to a small extent, but there are health concerns if not executed properly. Freezing involves blanching and vacuum packing the vegetables into polythene bags. There is also a tradition in Kenya and Tanzania of using powdered vegetables to prepare soups or stews (e.g., as a bouillon), or to fortify maize or millet flour. The use of powdered vegetables with sesame (simsim) to make healthy snacks have been documented in Kenya, including simshade (a mixture of nightshade and sesame), simco (cowpea and sesame), and simama (amaranth and sesame) snacks. Such processed snacks are still being tested and are not yet widely available, despite evidence that wealthier urban consumers are willing to pay for such products. Ingredients that have minor effects on taste and appearance are regarded more positively than those that alter food products more notably.
African leafy vegetables are often considered a poor man’s food: people generally prefer starchy staples, meat, and imported vegetables, resulting in low consumer awareness of the nutrition and health benefits associated with local leafy vegetables. This perception has changed among wealthier urban consumers, but consumption of African leafy vegetables nevertheless remains low. Although there is much potential for processing these vegetables, currently most processing remains small-scale and artisanal. The link between producers and consumers is not organised, prices are volatile, and compliance with food safety standards is low. Some processing options have low consumer acceptance; for instance, a study in Kenya showed that 44% of consumers were not willing to pay for frozen cowpea leaves, and 70% were not interested in frozen vegetables in general, indicating the need to create awareness of the nutritional value of frozen vegetables.
Government policy objectives in Kenya and Tanzania are geared toward ensuring that all citizens have an adequate, diverse, and healthy diet through improved storage and processing of food commodities, including vegetables. However, research efforts, extension services, policies, and subsidies largely ignore traditional African vegetables, and mainly target staples and food and vegetables meant for export.