PROPERTIES AND USES OF THE SEED CAKE
Once the oil is extracted, up to 50 percent of the original seed weight remains as seed cake residue, mainly in the form of protein and carbohydrates. The amount of oil left in the seed cake depends on the extraction process. There are trade-offs for the seed cake. It may be used as fertilizer, fuel or, if it is detoxified or if non-toxic varieties are used, it can be used as animal fodder. However, it is significant that not returning the seed cake to the plantation as fertilizer reduces the utility of jatropha in improving degraded land.
Jatropha seed cake (JSC) has been shown to be suitable for the fermentative production of itaconic acid. The Press cake has mineral contents of nitrogen (6%), phosphorous (2.75%) and potassium (0.94%) similar to chicken manure, the press cake can be used as organic fertilizer. An application of 1 ton press cake is equivalent to 200 kg of mineral fertilizer (NPK 12:24:12). This work shows that the substrate concentration, incubation time, inoculum size and pH all affect the production of itaconic acid on Jatropha seed cake and the optimized physico-chemical parameters for fermentation of Jatropha Seed Cake for the production of itaconic acid are: PH 4 inoculum sizes of 5 ml and JSC concentration of 40%.
As the cake which is a waste byproduct of the biodiesel pro-diction process accumulates over time, it can be utilized in a bid for value addition, as a good raw material for itaconicacid production and at the same time, solve the problem of safe disposal of the waste.
Jatropha Curcas seed-cake was evaluated for use as a solid state fermentation substrate for production of cellulolytic and xylanolytic enzymes by Aspergillus Niger. Supplementation of the seedcake with 10% thatch grass (Hyperrhaenia sp.) resulted in a fivefold increase in xylanase production. Ammonium chloride supplementation increased production of xylanase by 13%. Under the same conditions, cellulase production was not influenced by supplementation with grass or the nitrogen sources used. Maximum xylanase was produced at 25 °C whilst cellulase was maximally produced at 40 °C. Highest xylanase activity was obtained when the cultures had an initial pH of 3 whereas cellulase was maximally produced at an initial pH of 5. Under optimized conditions, 6087 U and 3974 U of xylanase and cellulase respectively were obtained per gram of substrate. Zymograms of crude enzyme extracts showed six active bands ranging from 20 kDa to 43 kDa for cellulase and a 31 kDa active band for xylanase.