Microbial and Chemical Profile of Fermented Cassava Leaves From Selected Kenyan Coastal Varieties

Abstract

Cassava (Manihot escutenta, Crantz), is one of the high yielding, disease and drought resistant crop that can be used as an alternative to maize in Kenya. The leaves are highly nutritious and serve as an alternative to green leafy vegetables. However, cassava leaves production, consumption and processing has been low due to the lack of a well-structured cassava value chain and standard postharvest handling practices. Additionally, the high content of anti-nutrients discourages consumption at household. This study sought to evaluate the harvesting and postharvest practices, microbial and chemical profile of fermented cassava leaves from selected Kenyan coastal varieties. A total of 247 respondents were nominated from the two counties 120 and 127 respondents in Kilifi and Taita Taveta respectively. A completely randomized experimental design was used for chemical and microbial analysis. Almost all respondents (99.6%) grew cassava for food and Kibanda meno was the most preferred variety. In both counties, farmers harvested few leaves or piecemeal by handpicking and most commonly in the morning hours. Additionally, cassava value addition was limited to drying (82.6%) and fermentation (4.1%). The respondents (65.2%) preserved cassava for a maximum of 15 days. Fermentation followed by oven-drying and sun-drying significantly (p<0.001) reduced the tannins, oxalates and cyanide to recommended levels. The sensory scores of the fermented leaves averaged at 5 points on a seven-point hedonic scale stating, that they were likeable in comparison to the non-fermented samples. The results also indicated that lactic acid bacteria (LAB) were the predominant microorganisms in cassava leaves fermentation. The mean log CFU of yeasts and molds, LAB and coliforms were 6.96, 7.99 and 8.70 respectively. Leaf position and cassava leaves variety significantly (p<0.001) influenced microbial load during fermentation. Since LAB is the predominant microorganism in cassava leaves fermentation there is need for isolation of its pure cultures. This study conclude that fermentation reduces the anti-nutrient content in cassava leaves making it safe for consumption thus should be adopted for value addition of cassava leaves.