Judul: Gingerol and shogaol contents, pungency intensity and anelists acceptance in oleoresin of gajah ginger (Zingiber officinale var. Roscoe), Emprit Ginger (Zingiber officinale var. Amarum), and Merah Ginger (Zingiber officinale var. Rubrum)
Abstrak: Ginger is one of traditional herb which is used widely in Indonesia. There are three main species of gingers in Indonesia i.e. “gajah” ginger, “emprit” ginger, and “merah” ginger. It is known that ginger contains bioactive components which also contribute to its flavor. Some of these bioactive components such as gingerol, shogaol, zingerone, and their derivatives are phenolic components which known as pungent properties of ginger. Homologs of gingerol, (6)-, (8)-, (10)-gingerol; and (6)-shogaol on “gajah”, “emprit”, and “merah” ginger was observed on this study along with sensory test (pungency intensity and hedonic test). The determination of (6)-, (8)-, (10)-gingerol and (6)-shogaol in dried ginger was measured by liquid chromatography with photodiode array detection (LC-PDA). The levels of (6)-, (8)-, (10)-gingerol and (6)-shogaol in the “gajah” ginger were 9.56 mg/g, 1.49 mg/g, 2.96 mg/g, and 0.92 mg/g, respectively; in the “emprit” ginger were 22.57 mg/g, 4.73 mg/g, 6.68 mg/g, and 2.24 mg/g, respectively; and in the “merah” ginger were 18.03 mg/g, 4.09 mg/g, 4.61 mg/g, and 1.36 mg/g, respectively. The levels of gingerols and shogaol found in “emprit” ginger were the highest compared to “gajah” and “merah” ginger. The pungency intensity of ginger oleoresin towards 30 panelists for “gajah”, “emprit”, and “merah” ginger, using 15 cm unstructured-line scale, was 2.25, 5.93, and 7.99, respectively. The result of hedonic test on the taste, aroma, and overall attributes of ginger oleoresin towards 78 panelists for “gajah” ginger using 7-category scales, were 4.14, 4.31, and 4.04, respectively; for “emprit” ginger were 4.26, 5.04, and 4.38, respectively; and for “merah” ginger were 4.42, 5.12, and 4.55, respectively. There was no significant difference of taste and overall acceptance among the three species. However, the aroma acceptance of “gajah” was significantly lower than “emprit” and “merah” ginger.
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Judul: Kendali Mutu Jahe Menggunakan Sidik Jari Kromatografi Cair Kinerja Tinggi dan Analisis Multivariat
Abstrak: Ginger is known to have pharmacology effect such as antioxidant, antiinflamation, and anticancer. The rhizome of ginger is widely used as component in various herbal medicine preparations so that needed some methods to guarantee its quality and pharmacology effect. The aim of this research was to evaluate the quality of gajah ginger rhizome by antioxidant activity assay, high performance liquid chromatography (HPLC) fingerprint pattern examination, major compound content determination, and also quality model establishment of ginger ethanol extracts from 3 areas, that is Ponorogo, Tangerang, and Bogor. All samples were indeed potential as very strong antioxidant. The result of HPLC analysis showed 6-, 8-, and 10-gingerol, also 6-shogaol as dominant compounds. Grouping based on content of dominant compounds and HPLC fingerprint that used principal component analysis resulted group I (Tangerang), group II (Ponorogo), and group III (Bogor). The quality model that was formed using partial least square discriminant analysis showed that antioxidant activity of ginger was more defined by composition of all compounds than by its dominant compounds.
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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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