Johan J.P. Baars
Cassava is a major food crop for approximately 700 million people, especially in African countries. A large quantity of waste is produced during processing of cassava, mainly consisting of tuber peels. Although previous research has shown that these peels can be an ingredient for substrate to cultivate mushrooms, yields were usually inferior compared to traditional substrates such as sawdust. In a project funded by the European Union (www.fp7-gratitude.eu/) trials were done for the production of oyster mushrooms using fermented peels and stems from cassava crops produced in Ghana. Four mushroom strains representing two species (Pleurotus ostreatus and Pleurotus pulmonarius) were grown on fermented substrates made from cassava waste (peels and stems) without further heating/sterilization. Peels and cassava stems were tested in different ratios and supplemented with different amounts of rice or wheat bran. All substrates colonized quickly (15–16 days) and time to pinning varied between 18 and 24 days. The P. pulmonarius strains produced three flushes within 47 days (starting from inoculation) and the P. ostreatus strains needed 57–63 days completing flush 3. Biological efficiencies after three flushes varied between 38 per cent and 100 per cent. Addition of bran (rice or wheat) increases yields significantly. The trials have shown that cassava waste can be used well for the production of oyster mushrooms and that production from substrates containing up to 75 per cent cassava peels compares well to yields obtained on the traditional sawdust-based substrates.