SUGARCANE BAGASSE PITH DRY PRETREATMENT FOR SINGLE CELL PROTEIN-PRODUCTION

The effect of spraying a solution of sodium hydroxide onto sugarcane bagasse pith, in such a low volume that no free liquid was present, was evaluated with respect to Single Cell Protein production (SCP), and biological degradability. This type of processing will be referred to as a dry pretreatment and it is compared with a wet pretreatment. In-vitro digestibility and microbial growth were obtained with a mixed culture of Cellulomonas flavigena and Xanthomonas sp. Maximum digestibility was 76% using dry pretreatment with a NaOH dosage of 0.1 g per g pith, a temperature of 50-degrees-C and moisture content of 80% (based on oven dry weight). A digestibility value of 71% was obtained for wet conditions, with 0.2 g NaOH per g pith, a temperature of 92-degrees-C, and a solid:liquid ratio of 1:10. Biomass production was higher in the dry pretreatment than the wet pretreatment, when washing of the treated pith was omitted before fermentation. The spraying was carried out using a rotary system, which permits a better surface area contact between the substrate and the alkali. In this way the NaOH was efficiently used allowing relatively low alkali concentrations. Furthermore, by eliminating the washing stage, the solubilized carbohydrate fraction is retained.