Judul: Optimasi Proses Peningkatan Ketidakjenuhan CPO Dwlam  Agroindustri Menggunakan Absidia corymbifera
Abstrak: Unsaturated fatty acids are fatty acids, which are related to the human health. The higher level of unsaturated fatty acid is proportional to the risk decrease of human heart disease. The level of unsaturated Crude Palm Oil (CPO) is defined as the amount of carbons double bond per unit weight of CPO.
Keyword: 

Judul: Optimation of Unsaturation Level Increase of Crude Palm Oil with Desaturase by Using Continuous Systems
Abstrak: Desaturase is the catalyst for the formation of the double bond carbon chains either monounsaturated fatty acids (MUFA) or polyunsaturated fatty acid (PUFA). Desaturase producing fungi can be used to increase the unsaturation of crude palm oil (CPO). In the present study the fungi used was Rhizopus oryzae, because it is edible. The purpose of this study was to test the ability of Rhizopus oryzae in producing desaturase, extending enzyme-substrarate contact time, and increasing unsaturation of crude palm oil using bioreactor system model of spiral hose with height variation. First, the fungi were cultured in liquid media with supplements containing certain salts and CPO using Erlenmeyer. After incubation, the culture supernatant was separated from the biomass (liquid fermentation). Liquid fermentation was transferred into a bioreactor system model of continuous spiral hose with height variations (50 cm, 100 cm, 150 cm, 200 cm and 250 cm). Palm oil was pumped from the bottom of the column using a peristaltic pump. CPO was then characterized by determining the iodine number, saponification number, acid number and fatty acid composition both before and after the bioconversion. The results showed that Rhizopus oryzae fermentation liquid was able to increase the unsaturation CPO and multiple unsaturated fatty acid content. On studied conditions, the maximum unsaturation increase occurred at a height of 200 cm with iodine value change of 17.091 g I2/100g CPO with the contact time for 35 minutes. This indicated that the longer the contact time, the higher the unsaturation of CPO. Iodine number could also decrease due to the oxidation of the C = C double bond, that was indicated from the results of iodine number at a height of 250 cm with iodine value change of 15.886 g I2/100g CPO for contact time of 47 minutes. At the optimum conditions, the saponification number was 183.489 g KOH/g CPO and acid number was 9.36 g KOH/g CPO with levels of free fatty acids (% FFA) of 0.936%. Fatty acid composition of palm oil after optimum bioconversion conditions showed increase in oleic acid, and linoleic acid.
Keyword: polyunsaturated fatty acid, liquid fermentation, desaturase enzymes, Rhizopus oryzae, and continuous systems

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