Enriquecimento protéico do mandacaru sem espinhos (Cereus jamacaru P. DC) e palma forrageira (Opuntia ficus-indica Mill) por fermentação semissólida.

Abstract

The microbial protein enrichment process by yeast Saccharomyces cerevisiae in semi-solid medium of mandacarp sem espinho (Cereus jamacaru P. DC) and pear cactus (Opuntia ficus indica Mill) was studied. The three variables of cultivation in the laboratory used were: inoculum's concentration (5, 10 and 15 %), substrate layer thickness (2, 4 and 6 cm) and temperature (30, 34 and 38°C). The production rate of dry materi (DM), gross protein (TP) and its increment (ITP), real protein (RP) and its increment (IRP), fibers in acid detergent (FAD) and neutral detergent (NDF), hemicelluloses (HC), total energy (TE), organic material (OM) and in vitro dry materi digestibility coefficient (VDMD) were determined. The obtained results were: variance analysis and linear models, which are valid at the levei of 95% of confidence coefficient. The kinetics .study of the semi-solid fermentations of the two cactus showed to have higher microorganism increments in the protein synthesis, for the fermentation period of 48 hours. The maximum protein amounts achieved under the conditions studied, in the present work, were 28 and 26% for TP, 320 and 400% for ITP, 14 and 11 % for RP and 280 and 300% for IRP for Cereus jamacaru P. DC and pear cactus mediums respectively. These values are compatible or greater than those of conventional concentrates of protein supplements used for animal feed. The protein concentrates (bio-products) of Cereus jamacaru P. DC and pear cactus had a higher in vitro digestibility index (98 %) and showed an increase in total energy values when compared with those of the substrates in natura. The sorption isotherms at 30, 35 e 40°C temperature, of the two cactus under study were obtained. In order to work at optimum water activity for the yeast growth it was observed that the fermentation process should be started with about 90% inital substrate moisture.The residual moisture of about 15% should be retained so that the protein enrichment can be maintained without needing cooling or additives. It is concluded that there had been an increase in the bioconversion efficiency. The cactus were transformed in a high value bio-product when compared to conventional concentrates and can be utilized an alternative animal food during the dry period of scarcity of animal food in the semiarid region of the northeast of Brazil.