Judul: Pemanfaatan Limbah Pod Kakao Sebagai Substrat Penghasil Asam Sitra! oleh Aspergillus niger
Abstrak: Penelitian telah dilakukan untuk memanfaatkan limbah pod kakao sebagai substrat penghasil asam sitrat oleh A. niger A TCC.11.266. Limbah pod yang digunakan diambil dari perkebunan kakao PTP Nusantara VIII, Rajamandala, Cianjur. Pod dikeringkan dan dibuat serbuk dengan ukuran 35 mesh. Media substrat semi-padat 35% disterilkan pada suhu 121 °c selama 2 jam dan diinokulasikan dengan A niger ATCC.11.266 (6 x 107 spora/ml) dan difermentasi selama 14 hari dalam penangas-air goyang 200 rpm pada suhu 30 °c. Waktu fermentasi dibuat bertingkat, selanjutnya diukur perubahan pH substrat dan dianalisis kadar total asam, kadar gula pereduksi substrat, kadar asam sitrat, dan kadar protein supernatan hasil fermentasi. Analisis dan pengukuran pH dimulai pada hari kedua fermentasi dengan jarak dua hari sampai dengan hari kesepuluhfermentasi. Pada hari kesebelas sampai akhir fermentasi, analisis komponen hasil fermentasi dan pengukuran pH substrat dilakukan setiap hari. Penelitian dilakukan dalam dua tahap, yaitu tahap pendahuluan yang meliputi: pembuatan media substrat pod kakao, analisis proksimat, dan peremajaan kultur murni A niger A TCC.11.266. Pada tahap lanjutan dilakukan: fermentasi produksi asam sitrat, pemanenan hasil fermentasi, pengukuran perubahan pH substrat, analisis kadar total asam dengan titrasi, kadar gula pereduksi substrat dengan metode DNS, kadar asam sitrat hasil fermentasi dengan kromatografi cair kinerja tinggi (KCKT), dan kadar protein supernatan hasil fermentasi dengan metode Bradford. Data dari analisis komponen hasil fermentasi, pengaruh waktu fermentasi terhadap perubahan pH dan kadar komponen, dianalisis dengan rancangan acak lengkap satu arah dan untuk melihat waktu fermentasi yang berpengaruh dilanjutkan dengan uji BNJ. dst ...
Keyword: Apergillus niger

Judul: Pemanfaatan Pod Kakao untuk Produksi Etanol melalui Hidrolisis Menggunakan Kapang Aspergillus niger dan Trichoderma viride
Abstrak: Indonesia is one of the largest cocoa producing country in the world, and according to harvest data from 2005, Indonesia produces 13% cocoa from the total world cocoa demand. Fresh cocoa fruit consists of 75.50% of the fruit shells, 21.18% of seeds and 2.60% of placenta. Cocoa pod is one of lignoselulosic waste containing of 31.25% cellulose. The cellulose composition large enough to make cocoa pod potential to be processed into ethanol. So far, ethanol production is more focused on raw materials such as cassava, sweet potatoes, sugar cane, sago, and several types of starch which is less effective because these materials compete with food. This research aimed to find out the effects of substrate’s type of cocoa pod, the type of mold, and time of hydrolysis optimized to produce high levels of reducing sugar and producing ethanol from the best hydrolisate. This research were performed into three stages. The first stage was the preliminary stage that includes the characterization of cocoa pods and pretreatment on cocoa pod including reduction in size, degumming, and delignification. The second stage was the hydrolysis of cocoa pod using two types of fungus (Aspergillus niger and Trichoderma viride), two types of substrates (non-delignified and delignified cocoa pods), hydrolysis time (11 days), sampling on days 1, 3, 5, 7, 9, and 11. Last stage was the fermentation using the best hydrolisate, using Saccharomyces cerevisiae culture. This research utilized completely randomized factorial design with three factors and two replications. The first factor was the type of fungus, which consists of two levels of Aspergillus niger and Trichoderma viride. The second factor was the hydrolysis time with 6 degree of day (1, 3, 5, 7, 9, and 11). The third factor was the type of substrate with two levels of the substrate non-delignified and delignified cocoa pods. Material characterization results obtained the cellulose content of cocoa pods is 28.78% (wb), Hemicellulose 8.70% (wb) and 42.90% lignin (wb). After delignification the results obtained cellulose content is 32.23% (wb) and 31.00% lignin (wb). The delignification efficiency was 27,74%. Based on the results of range analysis with α <0.05 at the hydrolysis stage substrate types affected significantly on reducing sugar concentration, whereas the type of fungus and hydrolysis time does not affect real.
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Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model