Changes in biochemical composition of cassava and beet residues during solid state bioprocess with Pleurotus ostreatus

The development of the Pleurotus ostreatus in cassava (Manihot esculenta) and beet (Beta vulgaris) residues via solid state bioprocess (SSB) was evaluated in terms of variation of proximate composition, phenolic compounds, minerals, in vitro digestibility, fungal growth and lipase activity. The substrates were cultured at 30 °C for 35 days and sampled every 5 days. The amount of protein, and fibers of cassava residues, increased by 125.7%, and 253.2%, respectively. The beet residue showed a protein increment of 57.6%, and fibers of 232.7%. In beet residues, the lipid increase was of 261.7% while that for cassava residues was of 136.2%. The cassava residue showed a reduction in phenolic compounds from 18.07 mg of acid galic equivalent (AGE)/g to 4.17 mg AGE/g and beet from 30.96 mg to 3.50 mg. In vitro digestibility increased by 5.24% in cassava residues and 29.38% in beet residues. P. ostreatus reached 8.63 CFU/g (15 days) in cassava residue and 6.08 CFU/g (25 days) in beet residue. Maximum lipase activity was 0.71 U/g (35 days) in beet residues and 0.46 U/g (20 days) in cassava residues. Both beet and cassava residues presented nutritional enrichment (carbohydrate reduction and increase of other compounds) and increased in vitro digestibility with P. ostreatus via SSB. This application presents great biotechnological potentiality, e.g. the utilization as a low-cost nutrient source for animal feed.