Hidrólise enzimática da fibra de caju submetida a diferentes pré-tratamentos: recuperação e reuso do complexo enzimático

Abstract

In this work, different strategies of reuse of the cellulolytic complex du ring the enzymatic hydrolysis from cashew apple fiber was studied as a strategy to r educe the costs of this process. To evaluate the effect of composition from material in the processes of reuse, cashew apple fiber was pretreated by acid followed by alkali (FC - HOH), or alkaline hydrogen peroxide (FC - PHA) or dilute acid (FC - H). Two enzymat ic hydrolysis were carried out: e nzymatic hydrolysis I (EH I) was performed using only the cellulase enzymatic complex (15 FPU/g ce l lulose ) and e nzymatic hydrolysis II (EH II) was conducted using the cellulase enzymatic complex (15 FPU/g cellulose ) and cellobi ase (60 CBU/g cel l ulose ). The substrate FC - HOH showed the highest yields, 93% ± 3% for EH I, and 99% ± 1% for EH II. S trategies capable of reuse the enzyme bound to the residual solid and free in solution were held for two successive hydrolysis cycles. In strategy I, per centages of the residual solid obtained of E H I ( 30, 50, 80 and 100% ) were evaluated , which it was placed in contact with the fresh substrate without addition of enzym e . The assays using 100% residual solid show ed the best yields, for FC - HOH was achieved an yield of 32.06% ± 1.22% and enzymatic recovery of 87.3% of the initial enzyme charge (15 FPU/ g cellulose) ; for FC - PHA , the yield and recovery were 25.27% ± 0.92% and 70.5% , respectively; for FC - H was obtained the lower yields (16.89% ± 1.47%) and one recovery rate of 65%. Knowing the percentage of greater enzymatic recovery, the strategies III (without supplementation of enzyme) and V (with supplementation of enzyme) w ere carried out using the residual solid ( Enzymatic hydrolysis II), which was placed in contact with the fresh substrate. For strategies III and V, in the first reuse with FC - HOH it was possible to recover the highest amount of enzymes (14.89 FPU/g c ellulos e ) and an economy of R$ 2 . 140 million p er ton of cellulose. The yields of hydrolysis were 38% ± 4% and 58% ± 1% for R1 and R2 recycles , respectively. In the second reuse, for strategy III, 13.02 FPU/ g cellulose was adsorbed to fiber and a hydrolysis yield of 9.8% ± 0.5%, achieving a n economy of R $ 1 . 871 million . The free enzymes in solution (hydrolyzed liquid) were recovered using strategies II and IV, in which the hydrolyzed liquid was placed in contact with the fresh substrate, in strat egy IV, there was cellulase supplementation. It was observed that 83% of the initial load was adsorbed to the FC - H, and presented an economy of R$ 2 . 027 million , for strategy III, but with yield equal to 2.78% ± 1.08%. Among the substrates studied the FC - H OH presented the best results and the IV str ategy stood out from the others.