ARAÚJO, L. F.; http://lattes.cnpq.br/1326245116434253; ARAÚJO, Lúcia de Fátima.
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.