Aplikasi Pemanasan Microwave dalam Hidrolisis Biomassa Cocoa Pod Husk (CPH) untuk Produksi Bioetanol

Abstract

Cocoa Pod Husk (CH) is one of the most abundant biomass in Indonesia, but its use is still limited to making fertilizer and animal feed. The abundant amount of CPH and its contents are considered suitable to be used as raw material in the second generation ofethanol production. The high concentration of lignin in CPH can inhibit the rate of hydrolysis, so it is necessary to pre-treat CPH samples. It is also necessary to pay attention to the method used in the process of hydrolyzing CPH samples prior to fermentation so that they can produce high ethanol during the fermentation process. Fermentation stress can affect the growth and productivity of yeast isolates, so it is necessary to characterize the isolates in terms of their resistance to various fermentation stresses. This research began with the process of preparing CPH samples and continued with the process of hydrolyzing the samples using microwave heating. Rejuvenation of yeast isolates was carried out by growing isolates on YPD medium. Yeast isolates were then selected based on their ability to ferment xylose using oxidative fermentative media. Isolate characterization was carried out on selected yeast isolates including resistance to temperature stress (30 °C, 37 °C, and 40 °C), pH stress (3, 4, and 5), and ethanol stress (6%, 8%, 10%, 12%, and 14%) using the spot assay method. Growth curves were prepared by measuring the optical density (OD) value of the yeast isolates Y001 and Y003 at a wavelength of 600 nm per 6 hours for 72 hours. The final stage of this study was to measure the ethanol produced during the fermentation process using HPLCevery 24 hours for 96 hours. Analysis of the chemical components of the two P H samples before and after treatment using hydrogen peroxide showed a decrease in lignin levels of34% of the total lignin samples. Hydrolysis of ICS 60 variety CPH samples using the microwave-assisted hydrolysis method produced hydrolysate with a high concentration of glucose-xylose with a heating time of 12 minutes. Selection of ethanol fermenting yeast using oxidative fermentative media showed that isolates Y001 and Y003 were able to ferment xylose and were resistant to various fermentation stresses including being able to grow up to 40 °C, resistant to ethanol stress up to 14% and able to grow at pH .3 The highest ethanol was produced at the E3 (liquid hydrolysate + 1% yeast extract + 2% peptone + 2% glucose + 2% xylose) treatment was 11.3 g/L with ethanol yield of 0.31 g/g.

Cocoa Pod Husk (CPH) merupakan salah satu biomassa yang melimpahdi Indonesia, akan tetapi pemanfaatannya mash terbatas pada pembuatan pupuk dan pakan ternak. Melimpahnya jumlah CPH dan kandungan yang dimilikinyadinilai c o o k untuk dijadikan bahan baku dalam produksi etanol generasi kedua. Konsentrasi lignin yang tinggi pada CPH dapat menghambat laju hidrolisis sehingga perlu dilakukannya pra-perlakuan sampel CPH. Metode yang digunakan dalam proses hidrolisis sampel P H sebelum difermentasi juga perlu diperhatikan sehingga dapat menghasilkan etanol yang tinggi s a t proses fermentasi. Cekaman fermentasi dapat mempengaruhi pertumbuhan dan produktivitas isolat khamir sehingga perlu dilakukan karakterisasi isolat berupa ketahanannya terhadap berbagai cekaman fermentasi. Penelitian in diawali dengan proses persiapan sampel P H dan dilanjutkan dengan proses hidrolisis sampel dengan pemanasan microwave. Peremajaan isolat khamir dilakukan dengan menumbuhkan isolat pada medium YPD. Isolat khamir kemudian diseleksi berdasarkan kemampuannya dalam memfermentasikan xilosa dengan menggunakan media oxidative fermentative. Karakterisasi isolat dilakukan terhadap isolat khamir terpilih meliputi ketahanan terhadap cekaman suhu (30 °C, 37 °C, dan 40 °C), cekaman pH (3, ,4 dan 5), serta cekaman etanol (6%, 8%, 10%, 12%, dan 14%) dengan menggunakan metode spot assay. Pembuatan kurva tumbuh dilakukan dengan mengukur nilai optical density (OD) kultur isolat khamir Y001 dan Y003 pada panjang gelombang 600 nm per 6 jam selama 72 jam. Tahap akhir penelitian in vaitu mengukur etanol yang dihasilkan selama proses fermentasi menggunakan HPLC setiap 24 jam selama 96 jam. Analisis komponen kimia kedua sampel P H sebelum dan sesudah perlakuan menggunakan hidrogen peroksida menunjukkan adanya penurunan kadar lignin sebesar 34% dari total lignin sampel. Hidrolisis sampel P H varietas ICS 60 menggunakan metode microwave-assisted hydrolysis menghasilkan hidrolisat dengan konsentrasi glukosa-xilosa yang tinggi dengan waktu pemanasan selama 12 menit. Seleksi khamir pemfermentasi etanol menggunakan media oxidative fermentative menunjukkan isolat Y001 dan Y003 mampu memfermentasikan xilosa dan than terhadap berbagai cekaman fermentasi diantaranya dapat tumbuh hingga suhu 40 °C, tahan terhadap cekaman etanol hingga 14% dan mampu tumbuh pada pH 3. Etanol tertinggi dihasilkan pada perlakuan E3 (hidrolisat cair + 1% ekstrak khamir + 2% pepton + 2% glukosa + 2% xilosa) sebesar 11.3 g/L dengan vield etanol menapai 0,31 g/g.