Judul: Karakteristik Sifat Fisikokimia dan Organoleptik Nasi dari Beberapa Varietas Beras
Abstrak: The physicochemical properties and sensory characteristics were studied for six varieties namely IR42, Inpara 3, Ciherang, Inpari 1, Inpari 2, and Inpari 6 Jete. Physicochemical parameters measured were amylose content (AC), in vitro digestibility of starch, gel consistency, amilography, water uptake ratio (WUR), and volume expansion. The sensory data on cooked rice obtained by scoring, hedonic, ranking test, and Quantitative Descriptive Analysis (QDA). The result showed that AC of varieties ranged from 18.87 to 28.60%. The highest digestibility of strach was found in Inpari 6 Jete. On the other hand, Inpari 6 Jete had the lowest gelatinization temperature. The gel consistency of six varieties were range from 32.25 to 86.25 mm. The WUR and volume expansion of all varieties were not significant. Scoring test showed that the colour of cooked rice from all varieties studied was white. The most favorite cooked rice was recorded in Inpari 6 Jete. Ranking test for aroma of cooked rice showed that inpara 3 was the most fragrant. There ware significant correlations between AC and some physicochemical properties and also sensory characteristics. AC was positively correlated with volume expansion (r=0.430, p<0.05) and the colour of cooked rice (r=0.752, p<0.01). On the other hand, AC was negatively correlated with gel consistency (r=-0.766, p<0.01), in vitro digestibility of starch (r=-0.633, p<0.01), glossy of cooked rice (r=-0.805, p<0.01), aroma (r=-0.502, p<0.05), and texture of cooked rice (r=-0.929, p<0.01).
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Judul: Kandungan 2-Asetil-1-Pirolina dan Heksanal pada Beberapa Varietas Beras (Oryza Sativa L.) Aromatik Selama Penyimpanan dengan Beragam Derajat Sosoh dan Jenis Pengemas
Abstrak: Scented rice or aromatic rice varieties is popular because of their flavor and texture. 2-Acetyl-1-pyrroline (2AP) contribute to pandan-leaves-like aroma, and hexanal is used as indicator of rancidity. Three aromatic cultivars (Mentik Wangi, Pandan Wangi, and Sintanur) with 100, 90, and 0% (brown rice) milling degree were stored in two types of packaging, i.e., plastic bag and hermetic bag for 4 months in room temperature. 2-Acetyl- 1-pyrroline and hexanal were determinded every 2 month during storage using gas chromatography mass spectrophotometer. Prescribed nutrient content with proximate analysis including moisture, ash, fat, protein, and amylose content, were done at the begining and at the end of storage time. Preference of rices was done by hedonic test. 2- Acetyl-1-pyrroline concentration decreasing during storage and as increasing with the milling degree. Brown rice have a highest hexanal than 90% and 100% of milling degree. Hexanal increased during 2 month storage, and decreased in 4 month storage. During storage, moisture, ash content, protein, and fat were still in standard range according to several references. Based on the amylose content, the texture all of rice before storage was sticky category and after four months of storage fell into smooth until hard texture. however ash and fat content were increasing. From preference test, Mentik Wangi 100% milling degree before storage is the most prefered rice than others. Both of hermetic bag and plastic bag gives no different influence in this case.
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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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