Think mango seeds are trash? This factory turns them into flour, fertiliser and briquettes

Inside an unassuming factory in Malivani Village, on the outskirts of Wote town, Makueni County, six workers are busy washing and peeling a heap of ripe mangoes.

But unlike other factories in the region, which turn mango pulp into puree, juice, or crisps, the focus here is on something different—the mango seed.

Tosheka, the startup operating the factory, uses these seeds to make flour, a specialised fertiliser, and heavy-duty biomass briquettes.

“Try this,” says Herman Muli, the founder of the enterprise, offering a fresh piece of mango seed kernel to Climate Action. The white nugget resembles coconut or cassava. “Take a bite,” he adds. The kernel is crunchy, leaving a bitter aftertaste.

“Although the mango kernel can be eaten raw, we usually blend it and dry the result in a sterile, shaded environment. Then we crush it in a conventional posho mill to produce a flour packed with essential nutrients. We mix it with maize and wheat flour at home, and our goal is to supply it to commercial flour millers,” explains Muli.

Identifying himself as a jack of all trades and an innovator, Muli's portfolio includes creations such as Weather Guard, a product that prevents dust, pollen, and cold from entering buildings and vehicles. He is also working on producing organic pesticides from neem and aloe vera plants. However, his mango seed enterprise is what excites him the most. "Unlocking the value of mango seeds has a huge impact on both nutrition and the environment," he says.

Studies show that mango kernels are rich in starch and protein. According to a 2002 report from the Food and Agriculture Organization (FAO), titled Mango: Post-Harvest Operations, mango kernel flour is widely used in India, one of the world's largest mango producers. The report highlights that mixing mango kernel flour with wheat flour is common in making chapatis.

Despite this, Muli’s enterprise is yet to gain widespread acceptance in the region, even though Makueni County produces two out of every three mangoes sold in Kenya, according to the Ministry of Agriculture.

When Muli first began mobilising the community to collect mango seeds, many locals were skeptical, dismissing his idea as impractical.

“At first, we thought he was crazy, especially when he claimed that mango seeds are edible,” recalls Mirriam Mutheu, a local resident who works at the factory. “We’ve been growing mangoes for decades, and it never occurred to us that the seeds could be used for anything other than planting seedlings. But we now realise that mango seeds can be turned into fertiliser, food, and even fuel.”

To maintain the quality of the mango kernel flour, Muli recommends using fresh, pest-free seeds. He has partnered with the Makueni Fruit Processors Cooperative Society, the largest group of mango producers in the region, to promote integrated pest management practices.

These include intercropping mangoes with castor beans, which help to fight certain pests. However, even damaged or old seeds are not wasted.

“We compost seeds that have been affected by pests to create a specialised organic fertiliser. We also combine them with croton seeds, clay, lime, and cassava juice to produce heavy-duty biomass briquettes using a unique formula,” Muli explains.

In the two years since Tosheka launched, the startup has processed 40 tonnes of mango seeds into fertiliser, flour, and briquettes. Muli believes the enterprise will eventually put more money in the pockets of local mango farmers while reducing environmental degradation.

Farmers who have used the fertiliser during the last planting season have praised its effectiveness, and environmentalists have applauded the briquettes as an eco-friendly alternative to charcoal and firewood, which contribute to deforestation.

Tosheka works closely with the community and Iviani Farm, a local mango crisp factory, to secure a steady supply of mango seeds.

“Mango seeds make up the bulk of mango waste, with the peels being the other significant component,” says Faith Mumo, the proprietor of the crisp factory. “Mango waste is a major headache for us since proper dumping sites are scarce in the region. When left to rot, the waste releases nitrogen gas into the atmosphere. That’s why we’re relieved to have a regular arrangement for offloading our waste.”

Tosheka has set its sights on collaborating with the Makueni Fruits Processing Plant, a Sh180 million facility established by the county government to reduce post-harvest losses.

The factory processes 100 tonnes of mangoes per season, but it often faces complaints from the local community about waste pollution. These issues could escalate as the county and national governments have secured a partnership with a Russian investor to expand the factory's operations.

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