Judul: Edible Film Komposit Pati TapiokaAgar Kertas Terplastisasi Gliserol dan Limonena
Abstrak: Edible film is a food packaging material which can be consumed directly. The objective of this research is to composite edible film with tapioca starch, agar and plasticizers, namely glycerol and limonene. Edible film was made in 2 conditions, by adding fixed agar constituent (10%w/w) and fixed glycerol constituent (10%w/w), while other parameters were varied. Thermal analysis, specific gravity, tensile strength, water vapor permeability, and morphology of edible film were analyzed as it was applied for strawberry packaging. The addition of agar increased the specific gravity and tensile strength of edible film but percentage of elongation and water vapor permeability decreased. The composition of agar:glycerol:limonene (10:5:5) (%w/w) showed high tensile strength and specific gravity but low water vapor permeability. Thermal analysis showed decreasing of melting point was occurred when the concentration of limonene was increased. In addition, single melting point peak showed edible film was homogenous, this result was supported with morphology analysis. Edible film which was made of agar:glycerol:limonene (10:5:5) (%w/w) composition resulted in the longer shelf-life of strawberry for 3 days
Keyword: Bogor Agricultural University (IPB), tapioca starch, glycerol, edible film, agar

Judul: Edible film pati tapioka terplastisasi gliserol dengan penambahan agar
Abstrak: Edible films is one of biodegradable packaging that can be consumed with foodstuffs. Tapioca starch edible film plasticized by glycerol and combined with agar is one of alternative as a food packaging material. Films are made from food grade materials, so they are safe to be consumed. Tapioca starch-glycerol composition is 8:2 added with various concentration of agar 0, 1, 2, 3, and 4%. Films produced were analyzed for tensile strength, density, water vapor permeability, fungtional group, morphology, and application on fruit. Film added with 4% agar is the optimum composition with 4.4156 MPa tensile strength and the percentage elongation of 13.58%. Water vapor permeability of that edible films is 1.2780 x 10-9 g s-1 m-1 Pa-1. Morphology analysis shows that there are granules in the film, it means that film surface is not homogeneous. Functional group analysis shows that the process of film making happened physically. Testing on strawberry shows that edible film can stand water vapor permeability.
Keyword: agar, edible film, tapioca starch., glycerol

Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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