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: Effect of Soaking Porang Chips (Amorphopahllus oncophyllus) in Tamarind Solution on Calcium Oxalate Content in Porang Flour
Abstrak: KIREINA GUSTI SAFIRA. Pengaruh perendaman chips porang (Amorphopallus oncophyllus) dalam larutan asam jawa terhadap kadar kalsium oksalat pada tepung porang. Dibimbing oleh USWATUN HASANAH. Umbi porang merupakan komoditas ekspor dengan diekspor dalam bentuk chips. Chips porang memiliki kadar kalsium oksalat tinggi yang menyebabkan rasa gatal dan batu ginjal sehingga perlu diturunkan. Penelitian bertujuan mengetahui pengaruh larutan asam jawa sebagai perlakuan perendaman dalam menurunkan kadar kalsium oksalat pada tepung porang. Tahapan penelitian meliputi pembuatan chips porang, perlakuan perendaman chips porang dengan pengadukan dalam larutan asam jawa konsentrasi 5 − 15% selama 30 − 90 menit, pengeringan, penggilingan, pengayakan chips porang menjadi tepung porang, dan analisis tepung porang. Metode analisis kadar kalsium oksalat menggunakan metode titrasi permanganat. Uji statistik menggunakan ANOVA dan uji lanjutan DMRT. Tepung porang dengan kadar kalsium oksalat terendah didapatkan tepung hasil perlakuan perendaman larutan asam jawa konsentrasi 15% selama 90 menit. Karakteristik fisik dan kimia tepung porang perlakuan tersebut meliputi kadar air 10,46%, kadar abu 4,19%, kadar glukomanan 50,31%, kadar kalsium oksalat 132,23 (mg/100g), dan warna kekuningan. Konsentrasi dan lama waktu perendaman perlu ditingkatkan untuk mendapatkan kualitas tepung porang yang lebih baik, terutama penurunan
Keyword: umbi porang, kalsium oksalat, asam jawa, chips porang, tepung porang

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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