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"ABSTRAKBiodiesel (fatty acid methyl ester) telah diproduksi secara komersial melalui reaksi transesterifikasi minyak nabati dengan metanol menggunakan katalis alkali. Tetapi katalis alkali ini mempunyai beberapa kelemahan, seperti terjadinya reaksi pembentukan sabun, katalis yang bercampur homogen, dan proses pemurnian produk inilah yang menyebabkan harga biodiesel menjadi cukup mahal. Untuk mengatasi hal tersebut dikembangkan sintesis biodiesel menggunakan enzim lipase sebagai biokatalis. Biokatalis ini merupakan katalis heterogen, sehingga pemisahannya dari produk setelah reaksi berakhir dapat dilakukan dengan mudah. Namun, lipase terdeaktivasi oleh alkohol. Oleh karena itu, perlu dikembangkan metode baru untuk meningkatkan aktivitas dan stabilitas lipase dalam proses sintesis biodiesel. Metode baru yang akan dikembangkan adalah dengan cara mengganti alkohol dengan alkil asetat yang sama-sama berfungsi sebagai pensuplai alkil. Penelitian ini bertujuan untuk menentukan konsentrasi biodiesel (mol/L) yang terbentuk dari reaktan alkil asetat menggunakan biokatalis Candida rugosa terimmobilisasi dalam bentuk sol-gel (Novozym 435), melihat pengaruh biokatalis terhadap konsentrasi biodiesel yang dihasilkan dan uji stabilitas biokatralis tersebut. Reaksi dilakukan dalam reaktor batch dan analisa sampel menggunakan HPLC. Hasil penelitian menunjukan bahwa konsentrasi biodiesel terbesar yang dihasilkan dengan mengunakan biokatalis Novozym 435 adalah 15,02 (mol/L). Konsentrasi biokatalis terbesar yang digunakan yaitu 4 (% wt) terbukti menghasilkan konsentrasi biodiesel yang terbesar pula. Untuk stabilitas, setelah 3 kali reaksi, diperoleh yield biodiesel sebesar 11,82 %."

"Triglyceride hydrolysis using lipase has been proposed as a novel method to produce raw materials in food and cosmetic industries such as diacylglycerol, monoacylglycerol, glycerol and fatty acid. In order to design a reactor for utilizing this reaction on industrial scale, constructing a kinetic model is important. Since the substrates are oil and water, the hydrolysis takes place at oil-water interface. Furthermore, the triglyceride has three ester bonds, so that the hydrolysis stepwise proceeds. Thus, the reaction mechanism is very complicated. The difference between the interfacial and bulk concentrations of the enzyme, substrates and products, and the interfacial enzymatic reaction mechanism should be considered in the model."

"A large number of studies have been made on the triglyceride hydrolysis using lipase. However, the kinetics of the formation behavior of the intermediates, such as the diglyceride and monoglyceride, is still not clear, Triolein was hydrolyzed by Candida rugosa lipase in the biphasic oil-water system having a definite interfacial area. The ejects of the operating factor, such as the oil-water interfacial area and the initial enzyme concentration, on the consecutive hydrolysis behavior were investigated The kinetic model was proposed by considering a Langmuir adsorption isotherm of lipase in the bulk of the water phase on the oil-water interface and an irreversible pseudo first order consecutive reaction mechanism. The model well described the ejects of the initial enzyme concentration and the interfacial area on the consecutive triolein hydrolysis for not only the end product bitt also the intermediate products."

"Synthetic biodiesel using biocatalyst is an emerging and attracting alternative process to replace the conventional process. However, biocatalyst is easy to be deactivated by alcohol, which is a reactant in biodiesel synthesis reaction. Therefore, it is needed to develop new method to maintain the activity and stability of the biocatalyst during reaction. New method to be developed is by changing the reaction route which is using alcohol to the reaction route which is not using alcohol. Route reaction of non alcohol can be done by changing the alkyl alcohol with alkyl acetate. Both have the same function as alkyl supply during the reaction. In this paper, the research results of the synthesis biodiesel via route of non alcohol using biocatalyst Novozym 435 are presented In this reaction, methyl acetate is reacted with triglyceride from used fried oil in batch reactor. The reactants and products were analyzed using HPLC. The Results showed that Novozym 435 can convert trioleat up to 93.24% under the condition of 4% wt substrate of the biocatalyst concentration, oil/alkyl mole ratio equal to 1/I2 in 50 hour reaction. Stability test indicate that the activity of the immobilized biocatalyst still remain after three reaction cycles."

"Diasilgliserol, suatu komponen yang terdapat dalam minyak nabati memiliki fungsi fisiologis yang menguntungkan, terutama sebagai minyak yang memiliki efek antiobesitas dan anti peningkatan lemak tubuh. Berbagai studi untuk mensintesis diasilgliserol secara efisien telah dilakukan para peneliti di Jepang. Esterifikasi asam lemak dan gliserol menggunakan biokatalis telah digunakan sebagai proses sintesis yang efisien dalam skala industri. Sebuah model kinetika sintesis diasilgliserol diajukan, namun model ini sangat spesifik sehingga kurang sesuai untuk diaplikasikan dalam kondisi yang berbeda. Pada studi kali ini diajukan sebuah model untuk reaksi sintesis diasilgliserol melalui esterifikasi gliserol oleh asam lemak secara bertahap dengan asumsi dan kondisi yang lebih umum. Metode Runge-Kutta digunakan pada perhitungan konsentrasi substrat secara numerik. Model ini berguna dalam melakukan prediksi terhadap perilaku substrat pada esterifikasi asam lemak dan gliserol yang sulit untuk ditentukan secara eksperimen, serta sebagai prediksi dalam perancangan sistem untuk mensintesis diasilgliserol pada skala berbeda.

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Diacylglycerol, a component of natural oil has beneficial physiological function, mainly as oil with anti-obesity and anti fat accumulation effect. Several studies for efficient synthesis of diacylglycerol have been done by researchers in Japan. Esterification of fatty acid and glycerol using biocatalyst has been used as an effective synthesis process on it was industrial scale. A kinetics model for diacylglycerol synthesis was proposed, however, it was very specific so that not appropriate to be applied in different condition. In this study, a model for diacylglycerol synthesis by stepwise esterification of glycerol by fatty acid based on general assumption and condition is proposed. Runge-Kutta method is used in numerical calculation of substrate concentration. This model is useful for predicting behaviors of substrate at esterification of fatty acid and glycerol which is difficult to be measure experimentally, also as prediction in system design for diacylglycerol synthesis at different scale. "

"Sintesis biodiesel menggunakan biokatalis merupakan proses alternatif yang banyak menarik perhatian untuk menggantikan proses konvensional yang menggunakan katalis alkali karena mempunyai keunggulan di proses separasi yang lebih mudah dan terhindarnya dari reaksi samping yang merugikan. Namun, biokatalis ini mudah terdeaktivasi oleh alkohol yang merupakan reaktan dalam reaksi sintesis biodiesel. Oleh karena itu, perlu dikembangkan metode baru yang mampu mempertahankan aktivitas dan stabilitas biokatalis selama reaksi berlangsung. Metode baru yang akan dikembangkan adalah dengan mengubah rute reaksi dari menggunakan alkohol ke rute reaksi yang tidak menggunakan alkohol. Rute reaksi non alkohol bisa dilakukan dengan cara mengganti alkil alkohol dengan alkil asetat yang sama-sama berfungsi sebagai pensuplai alkil. Pada makalah ini disajikan hasil penelitian sintesis biodiesel rute non alkohol menggunakan biokatalis Novozym 435. Dalam reaksi ini, metil asetat direaksikan dengan trigliserida dari minyak jelantah dalam reaktor batch. HPLC digunakan untuk menganalisa reaktan dan produk. Hasil penelitian ini menunjukan Novozym 435 mampu mengkonversi trioleat sebesar 93.24% pada kondisi konsentrasi biokatalis sebesar 4% wt substrat, rasio mol minyak/alkil sebesar 1/12 selama 50 jam reaksi. Uji stabilitas menunjukkan bahwa biokatalis terimobilisasi ini masih memiliki aktivitas untuk tiga kali siklus reaksi. Model Kinetika berbasis mekanisme Michaelis-Menten mampu menggambarkan reaksi ini dengan ditandai hasil fitting yang cukup memuaskan dengan hasil eksperimen.

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Synthetic biodiesel using biocatalyst is an emerging and attracting alternative process to replace the conventional process. However, biocatalyst is easy to be deactivated by alcohol, which is a reactant in biodiesel synthesis reaction. Therefore, it is needed to develop new method to maintain the activity and stability of the biocatalyst during reaction. New method to be developed is by changing the reaction route which is using alcohol to the reaction route which is not using alcohol. Route reaction of non alcohol can be done by changing the alkyl alcohol with alkyl acetate. Both have the same function as alkyl supply during the reaction. In this paper, the research results of the synthesis biodiesel via route of non alcohol using biocatalyst Novozym 435 are presented. In this reaction, methyl acetate is reacted with triglyceride from used fried oil in batch reactor. The reactants and products were analyzed using HPLC. The Results showed that Novozym 435 can convert trioleat up to 93.24% under the condition of 4% wt substrate of the biocatalyst concentration, oil/alkyl mole ratio equal to 1/12 in 50 hour reaction. Stability test indicate that the activity of the immobilized biocatalyst still remain after three reaction cycles."

"Palm Oil Mill Effluent (POME) is an agro-industrial waste product with high availability and which contains high quantities of organic compounds that are necessary for microbial growth. Cultures of Pseudomonas aeruginosa were grown in POME to produce lipase using the submerged fermentation method. The objective of this study is to obtain the optimum value of lipase activity produced by the cultures of Pseudomonas aeruginosa using POME as the substrate through the submerged fermentation method and to obtain the dry extract of lipase. In the study, the one factor at a time (OFAT) method was applied, which allowed observation of the effect of inoculum and additional nutrient concentrations, such as Ca2+ ion, olive oil, peptone and Tween 80, on the activity of lipase. These factors were investigated in shake flask fermentation at 30°C over 96 hours. The activity unit of lipase was determined by the titrimetric reaction of olive oil hydrolysis using crude lipase. The optimum value of the lipase activity unit (1.327 U/mL) was gained when 3% (v/v) of inoculum, 4 mM of Ca2+ ion, 0.4% (v/v) of olive oil, 0.9% (m/v) of peptone, and 0.9% of Tween 80 were added into the medium. Crude lipase was then dried using a spray dryer. Subsequently, 15.643 g of dry extract lipase was obtained from 500 mL of cell free supernatant. In further research, the lipase activity assay would be better achieved using the p-nitrophenyl palmitate hydrolysis method and examined by a spectrophotometer."