PENINGKATAN DIGESTIBILITAS DAN PERUBAHAN STRUKTUR TANDAN KOSONG KELAPA SAWIT OLEH PRETREATMENT Pleurotus floridanus DAN ASAM FOSFAT

Isroi, Prof. Dr. Zaenal Bachrudin.

2013 | Disertasi | S3 Bioteknologi

Tandan kosong kelapa sawit (TKKS) tersedia melimpah dan belum optimal dimanfaatkan sebagai bahan baku produk berbasis lignoselulosa. TKKS memiliki digestibilitas rendah dan sulit diolah menjadi produk turunannya. Penelitian ini bertujuan untuk meningkatkan digestibilitas TKKS melalui pretreatment biologi dengan jamur pelapuk putih (JPP). Tahapan penelitian ini adalah (1) pemilihan JPP yang selektif mendegradasi lignin, (2) peningkatan digestibilitas TKKS dengan penambahan Mn2+ dan Cu2+, (3) peningkatan digestibilitas TKKS dengan pretreatment kombinasi biologi dengan asam fosfat. Penelitian dilakukan dalam skala laboratorium. Pengamatan dilakukan terhadap perubahan berat kering, lignin, selulosa, hemiselulosa, struktur fisik dengan analisa SEM, gugus fungsional dengan analisa FTIR, dan kristalinitas selulosa. Seleksi dilakukan terhadap Polyota sp, Pleurotus sp,dan Agraily sp. Pleurotus sp dipilih untuk percobaan selanjutnya dan diidentifikasi sebagai P. floridnaus LIPIMC966, karena dapat menurunkan kandungan lignin dari 19.63% menjadi 15.22%, hemiselulosa dari 14.77% menjadi 12.63%, dan meningkatkan selulosa dari 39.92% menjadi 56.04%. Penambahan Mn2+ dan Cu2+ pada pretreatment biologi menggunakan P. floridanus mengurangi bobot kering dari 27,43% menjadi 32,88%; kandungan lignin hingga 43,17% (Mn2+) dan 34,08% (Cu2+), hemiselulosa hingga 32,82%, sedangkan kadar selulosa relatif konstan. Kombinasi pretreatment biologi menggunakan P. floridanus dan asam fosfat dievaluasi berdasarkan perubahan komponen lignoselulosa, struktural dan morfologi. Degradasi karbohidrat setelah pretreatment biologi, asam fosfat, dan kombinasi biologi dan asam fosfat masing-masing adalah 7,88%, 35,65%, dan 33,77%. Pretreatment mengubah ikatan hidrogen dari selulosa dan ikatan antara lignin dan karbohidrat, yang berhubungan dengan kristalinitas selulosa. Kristalinitas selulosa yang ditunjukkan dengan lateral order index setelah pretreatment secara berturutturut adalah adalah 2,77 (tanpa pretreatment), 1,42 (biologi), 0,67 (asam fosfat), dan 0,60 (kombinasi biologi dan asam fosfat). Pretreatment asam fosfat merusak struktur dan morfologi serat TKKS yang ditunjukkan dari hasil analisis SEM. Pretreatments telah meningkatkan digestibilitas TKKS masing-masing 4 (biologi), 6,3 (asam fosfat), dan 7,4 (biologi dan asam fosfat) kali lipat dibandingkan tanpa pretreatment.

Oil palm empty fruit bunches (OPEFB) is abundance and not optimally utilized as lignocellulose-based products. OPEFB has low digestibility and difficult to process into its derivatives. This study aims to improve digestibility of OPEFB through biological pretreatment with white-rot fungi. Stages of this study were (1) selection white-rot fungi which selectively degrade lignin, (2) enhancement the digestibility of OPEFB by Mn2+ and Cu2+ addition, (3) improvement digestibility of OPEFB by a combination of biological pretreatment with phosphoric acid pretreatment. All the studies were conducted on laboratory scale. Observations were made on the changes of dry weight, lignin, cellulose, hemicellulose, physical structure by SEM analysis, functional groups by FTIR analysis, and the crystallinity of cellulose. Screening is done on Polyota sp, Pleurotus sp and sp Agraily. Pleurotus sp chosen for further experiments and identified as P. Floridanus LIPIMC966, because it can alter the lignin content from 19.63% to 15.22%, hemicellulose from 14.77% to 12.63%, and increase cellulose from 39.92% to 56.04%. The addition effect of Mn2+ and Cu2+ on the biological pretreatment using P. Floridanus could reduces the dry weight from 27.43% to 32.88%; lignin content up to 43.17% (Mn2+) and 34.08% (Cu2+), hemicellulose content up to 32.82%, while cellulose content remained constant. Combination of biological pretreatment and phosphoric acid were evaluated based on the changes in components of lignocellulose, a structural and morphology. Carbohydrate degradation after biological pretreatment, phosphoric acid, and a combination of biology and phosphoric acid are 7.88%, 35.65%, and 33.77%, respectivelly. Pretreatment changed the hydrogen bonding of the cellulose and linked between lignin and carbohydrates, which is related to the crystallinity of the cellulose. The crystallinity of the cellulose as indicated by lateral order index after pretreatment are 2.77 (without pretreatment), 1.42 (biology), 0.67 (phosphoric acid), and 0.60 (a combination of biology and phosphoric acid), respectively. Phosphoric acid pretreatment damaged the structure and morphology of the OPEFB fibers shown by SEM analysis. Pretreatments have increased digestibility of the OPEFB 4 (biology), 6.3 (phosphoric acid), and 7.4 (biology and phosphoric acid)-fold compared with whitout pretreatment.

Kata Kunci : Tandan Kosong Kelapa Sawit, Pleurotus floridanus, Cu, Mn, pretreatment biologi, digestibilitas