Fermentation of Jatropha kernel cake (Jatropha curcas L.) using variaties of fungi on its chemical compositions, concentration of phorbolester, and digestibility

Abstract

This study consists of two stages. The first stage is to identify fungi that able to grow on Jatropha kernel cake (JKC) and the second is to determine digestibility of fermented JKC. In the first stage, the JKC is fermented using species of fungi, namely, Aspergillus niger, Neurospora sp. or
Rhizopus oligosphorus. After fermentation, the fermented JKCs (JKCF) are chemically analyses for DM, OM, CP, CF, NDF ADF and phorbolester contents. The second stage is to determine in sacco digestibility of the JKCF when fermented using selected fungi. The in sacco degradation is conducted according to Orskov and Ryle (1990). The results show that the fermentation very significantly (P <0.01) increases CP and very significantly (P <0.01) decreases content of CF, NDF and ADF, as well as phorbolester content of JKCF. Rhizopus oligosporus has the highest ability to increase CP content (26.82%), and to decrease NDF (51.04%), and ADF (55.87%). The decrease of CF is occurred best with Neurospora sp. (56.05%), the decrease of phorbolester occurs from 6.54 ppm before fermentation to 0.10 ppm after fermentation with Aspergillus niger, 0.14 ppm with Neurosphora sp. and 0.37 ppm with Rhizopus oligosporus. Based on its performances the Rhizopus oligosporus is the selected fungi for fermenting JKC. The degradation of DM and OM are highest when JKC and JKCF are incubated for 72 hours. Average degradation theory (DT) of DM and OM between JKC and JKCF are significantly different (P <0.01), much higher in JKCF than that in JKC, i.e.: 48.285 vs. 22.78% for DTDM and 61.06 vs. 55.78% for DTOM, respectively. It can be concluded that the fermentation able to increase CP content, the DTDM and DTOM, as well as, to
decrease fiber fractions and phorbolester contents