Effect of Physical Processing Methods on Chemical Composition and In vitro Digestibility of Castor Cake (Ricinus communis)

This study was carried out to determine the composition, in vitro OM digestibility and ricin content of the commercially available castor cake and to evolve simple processing methods to increase the nutritive value of the cake. The crude protein content in the differently processed castor cakes ranged from 29 to 35 % suggesting that they are good protein supplements. However crude fiber levels in all the samples were high (39–46%) and this resulted in low in-vitro organic matter digestibility (IVOMD<49%). The fiber fractions revealed that all the samples had high acid detergent lignin (ADL>35%) and this also could have contributed to the low IVOMD. The concentration of ricin in all the cakes ranged from 0.02% to 0.06%. Such lower levels could be attributed to the heat labile nature of the ricin as considerable amount of ricin gets destroyed during the extraction of the oil. Dehulling of the whole seeds or grinding of castor cake followed by sieving improved the quality of cake by reducing the fiber and ADL levels and increased protein content. Improvement in the quality of the cake was reflected in higher IVOMD values (>70%). The available castor cake can be graded as poor for livestock feeding in spite of the high protein content due to higher fiber levels, which adversely affects the utilization of the cake. By adopting simple processing techniques like dehulling or grinding and sieving, it is possible to reduce the fiber and lignin levels and increase the protein content of castor cake. Detoxifide cake would be a better protein supplement for the livestock would be more profitable to the endusers.