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 dari Perpaduan Karaginan, Selulosa Bakteri, dan Nanokarbon dengan Penaut Silang Asam Sitrat
Abstrak: Edible film is a film made of food grade materials. The film has mechanical properties and can act as a barrier so that it can prolong the shelf life of food products. Carrageenan is a base material of film derived from seaweed (Eucheuma cottonii). Addition of glycerol, bacterial cellulose, nanocarbons, and citric acid were used as compatibilizers to improve the mechanical properties of the carrageenan film. The optimum composition of edible film composed of glycerol, bacterial cellulose, nanocarbon 1.5%, and citric acid 10% increased tensile strength up to 160% and decrease of water vapor permeability up to 42% as compared to the carrageenan film. Tensile strength and water vapor permeability values met the standard for edible film as food packaging. The result of infrared spectrum showed the formation of the new functional groups on 1717 cm-1 that caused by the addition of citric acid crosslinker. Luminescence of nanocarbon can be detected using ultraviolet light at wavelength of 366 nm with the presence of blue color
Keyword: Bogor Agricultural University (IPB), water vapor permeability, nanocarbon, mechanical properties, citric acid crosslinker, carrageenan

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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