Abstract

Jatropha curcas Linnaeus, 1753 is a plant with several uses for communities in Cameroon and other African countries. However, present methods of detoxifying J. curcas kernel cake (JKC) to add value to its further utilization are too sophisticated for cottage operations in rural areas. This study sought to evaluate two auto-detoxification methods using the shellfish brine shrimp, Artemia salina (Linnaeus, 1758). Two identical J. curcas auto-detoxification apparatuses (JADA) were developed: one simulating diffuse daylight (DJADA) and the other solar irradiation (SJADA) conditions. JKC was pretreated by either soaking or boiling in water or lye. The pretreated samples were then placed in the JADA and either re-moistened to 66% dry matter (DM) or left un-moistened. Among the 14 pretreated samples, water soaked solar without re-moistening (WS1), lye soaked solar without re-moistening (LS1), and water soaked solar with re-moistening (WS2) had LC50 values above 1000 ppm after four weeks. On the other hand, un-moistened diffuse daylight spread (UDC), boiled in water and exposed to diffused daylight without remoistening (WD3), and un-moistened solar spread (USS) were the least detoxified within the same period of four weeks with LC50 values less than 60 ppm. Irrespective of the pretreatment, extracts from the SJADA had higher LC50 values when compared to that of DJADA. This finding suggests that sunlight is an important factor in auto-detoxification. The top three most efficient detoxified treatments: WS1, LS1 and WS2 are recommended for further development and testing with livestock and fish models. This study confirms that JKC is toxic, but under natural conditions is exposed to auto-detoxifying factors which are both endogenous and environmental. When these conditions are optimally manipulated, the detoxification rate is enhanced. Farmers in rural communities can use this strategy to detoxify JKC, transform it into livestock and fish dietary ingredient and consequently enhance its contribution to climate change mitigation.

Key words: Jatropha curcas, auto-detoxification, solar irradiation, Artemia salina.