Judul: Characterizations of Walur Flour (Amorphophallus campanulatus var. sylvetris) and Its Application in Noodle and Cookies.
Abstrak: Walur (Amorphophallus campanulatus var. sylvestris) is a source of carbohydrate that is available locally and potentially to be developed as a food source. Walur is a type of tuber containing high oxalate content causing itchiness and irritation on lips. The objective of this research was to produce walur flour with low oxalic content and to apply it as flour-subtitute in noodles and cookies. Walur root had moisture content of 74,46%, ash 4,89%, fat 14,41%, protein 6,42%, and carbohydrate 74,28% in dry basis. Oxalic content of walur was reduced by boiling at 40 oC for 3 hours, soaking in HCl 0,2 N solution for 30 minutes, 1% sodium bicarbonate solution for 5 minutes, washing and soaking in sodium metabisulfite 1000 ppm solution for 5 minutes before dried. This treatment reduced 95% of oxalic content and obtained whiteness value of 69%. RVA profile showed that walur flour had A type gelatinization pattern. Noodles product with 30% walur flour substitution and cookies product with 50% walur flour substitution were most acceptable sensoricaly.
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Judul: Modifikasi Pati Walur (Amorphophallus campanulatus var. Sylvestris) dengan Heat Moisture Treatment (HMT) serta Karakteristisasi Sifat Fisiko- Kimia dan Sifat Fungsionalnya
Abstrak: Walur is one of Indonesia’s indigenous tuber. Walur contains significant amount of carbohydrate. However, native starch extracted from walur has limited application due to its heat unstability. Therefore modification is needed to increase heat stability of walur starch. The starch is modified through Heat Moisture Treatment (HMT). The objective of this research is to study the influence of temperature and time on walur stach charactheristics. Native walur starch with moisture content of 17% is heated at 100 oC and 110oC in dry air oven for 6, 8, and 10 hours in closed container. The modified starch is analyzed for it pasting behaviour, swelling power, solubility, gel texture characteristics, freeze-thaw stability, starch granule morphology, starch birefringence, and starch melting characteristic. The results shows that HMT decreases peak viscosity, breakdown viscosity, swelling power and solubility, gel strength and elasticity, and melting enthalpy of starch. Modified walur starch has higher onset temperature (To), peak temperature (Tp), and final temperature (Tc).HMT increases heat stability of walur starch without significantly changes its birefringence property and granule morphology. It is also found that HMT increase syneresis of walur starch gel.
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Judul: Invers dari Matriks Tridiagonal Jacobi
Abstrak: Suatu matriks berukuran n×n dinamakan matriks tridiagonal jika untuk . Karya ilmiah ini memberikan algoritma yang mudah untuk menemukan invers ( dari matriks tridiagonal Jacobi yang simetrik dan nonsimetrik. Setiap elemen pada matriks tridiagonal ini adalah bilangan real. Terdapat 3 lema dan 2 teorema untuk menentukan . Lema pertama menunjukkan persamaan utama dalam membuktikan lema-lema dan teorema-teorema selanjutnya. Invers dari matriks yang simetrik dibuktikan oleh lema kedua yang menunjukkan elemen-elemen baris ke- dari . Selanjutnya, lema kedua dilengkapi dengan teorema pertama yang menunjukkan elemen-elemen dengan . Invers dari matriks yang nonsimetrik dibuktikan oleh lema ketiga yang menunjukkan elemen-elemen dengan dan elemen-elemen dengan dibuktikankan oleh teorema kedua.
Keyword: symmetric, nonsymmetric, matrix