Judul: Reduksi Senyawa Purin pada Emping Melalui Proses Perendaman
Abstrak: Emping has high purine content which can be related to the high uric acid level in blood that lead to joint inflamation due to the sendimentation of uric acid. The objective of this research is to prove that soaking process can reduce purine content in emping and to know the effect of the soaking process length in purine reduction. Soaking time (2, 5, and 12 hours) and emping brand (Sriti, A1 and Koki) are used as the parameters. Purine compounds such as adenine and hypoxanthine were analyzed by using High Performance Liquid Chromatography method with C18 column and UV detector. Selected samples were also analyzed by using sensory evaluation to know the consumer preference toward the treated fried emping. Results obtained during the research show that soaking process can reduce both adenine and hypoxanthin content in emping. Soaking for 2 hours in water can reduce adenine content 13 – 39% and hypoxanthine content 4 – 60%. Soaking process for 2 hours on emping can reduce up to 50% of total purine base content in A1 brand. Soaking time does not have any effect in purine reduction. Purine content after 5 and 12 hours soaking tend to be fluctuative. Emping samples that were soaked in the water have a decrease in preference by the panelists either in color, aroma, taste, texture or in overall, but still accepted by panelists.
Keyword: Bogor Agricultural University (IPB), purine reduction, HPLC, hypoxanthine, emping (belinjo cracker), adenine

Judul: Effect of acetic acid and table salt solution on reduction of calcium oxalate in porang banten flour (Amorphophallus muelleri)
Abstrak: Menurunnya harga umbi porang memberikan dampak perekonomian bagi petani. Petani pada umumnya hanya mengolah umbi porang menjadi chips porang maupun tepung porang dengan kadar kalsium oksalat tinggi. Konsumsi kalsium oksalat dalam jumlah tinggi mengakibatkan gatal di tenggorokan, rasa panas di mulut, serta menyebabkan batu ginjal. Penurunan kadar kalsium oksalat dapat dilakukan dengan perendaman larutan garam dapur maupun asam asetat. Penelitian ini bertujuan mempelajari pengaruh jenis larutan, teknik perendaman, serta lama perendaman terhadap kadar kalsium oksalat dan karakteristik tepung porang. Perlakuan yang diberikan pada chips porang basah berupa perendaman dalam CH3COOH 20% dan NaCl 15%. Teknik selama perendaman adalah pengadukan dan tanpa pengadukan, masing-masing selama 60, 90, dan 120 menit. Penelitian dilakukan dalam dua tahap yaitu pembuatan tepung porang serta karakterisasi fisikokimia yang terdiri dari analisis kadar air, kadar abu, kadar glukomanan, kadar kalsium oksalat, dan nilai derajat putih. Hasil penelitian menunjukkan bahwa perlakuan pengadukan dan semakin lama perendaman mampu menurunkan kadar kalsium oksalat. Hasil penelitian terbaik diperoleh dari perendaman NaCl dengan pengadukan selama 120 menit. Perlakuan tersebut menghasilkan kadar kalsium oksalat 69,59 mg/100 g dengan persentase penurunannya sebesar 92,24% dibandingkan kontrol. Hasil karakteristik lain yang diperoleh yaitu kadar air 9,88%, kadar abu 9,23%, kadar glukomanan 43,11%, dan derajat putih 50,65%., The decline in the price of porang tubers has an economic impact on farmers. Farmers generally only process porang tubers into porang chips and porang flour with high levels of calcium oxalate. Consumption of high amounts of calcium oxalate causes itching in the throat, burning sensation in the mouth, and causes kidney stones. The decrease in calcium oxalate levels can be done by soaking in a solution of table salt or acetic acid. This study aims to study the effect of the type of solution, immersion technique, and duration of immersion on calcium oxalate levels and characteristics of porang flour. The treatment given to wet porang chips was immersion in 20% CH3COOH and 15% NaCl. The technique during immersion was stirring and without stirring, for 60, 90, and 120 minutes, respectively. The research was conducted in two stages, namely the manufacture of porang flour and physicochemical characterization consisting of analysis of moisture content, ash content, glucomannan content, calcium oxalate content, and whiteness value. The results showed that the stirring treatment and the longer soaking were able to reduce calcium oxalate levels. The best research results were obtained from soaking NaCl with stirring for 120 minutes. This treatment resulted in calcium oxalate levels of 69.59 mg/100 g with a percentage decrease of 92.24% compared to controls. Other characteristic results obtained are 9.88% moisture content, 9.23% ash content, 43.11% glucomannan content, and 50.65% whiteness.
Keyword: acetic acid, calcium oxalate, glucomannan, porang flour, salt

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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