Judul: Pendugaan Umur Simpan Keripik Ubi Ungu Menggunakan Metode Accelerated Shelf-Life Testing Pendekatan Kadar Air Kritis
Abstrak: Keripik ubi ungu merupakan produk inovasi olahan ubi jalar ungu yang cukup banyak dikembangkan oleh Industri Kecil Menengah (IKM) di beberapa daerah yang berpotensial seperti di Desa Ciloto. Namun, sebagai produk pangan yang sensitif terhadap penyerapan uap air, keripik ubi ungu memiliki umur simpan yang terbatas dan relatif pendek. Sehingga, untuk mengetahui umur simpan produk tersebut dilakukan pengamatan pendugaan umur simpan menggunakan metode akselerasi pendekatan kadar air kritis. Variabel yang digunakan yaitu kadar air awal, kadar air kritis, kadar air kesetimbangan, kemiringan kurva ISA, permeabilitas kemasan, luas kemasan, bobot padatan per kemasan, dan tekanan uap air jenuh pada suhu penyimpanan. Diperoleh nilai kadar air awal keripik ubi ungu sebesar 0,0103 g H2O/g padatan, nilai kadar air kritis sebesar 0,0287 g H2O/g padatan, nilai kadar air kesetimbangan yang semakin besar seiring meningkatnya kelembaban relatif. Model yang terpilih yaitu model Henderson karena memiliki nilai R2 yaitu sebesar 0,9788 dengan persamaan log(In(1/(1-aw))) = 0,6344+0,5446 In Me dan nilai slope sebesar 0,1720. Pendugaan terbaik pada umur simpan keripik ubi ungu yaitu pada penyimpanan kelembaban relatif 70% menggunakan kadar air kritis SNI, diperoleh umur simpan pada kemasan PP yaitu selama 31 hari dan aluminium foil selama 123 hari. Kata kunci: kadar air, kelembaban relatif, keripik ubi ungu, umur simpan., Purple sweet potato chips are an innovative product of processed purple sweet potato which is quite widely developed by Small and Medium Industries (IKM) in several potential areas such as in Ciloto Village. However, as a food product that is sensitive to moisture absorption, purple sweet potato chips have a limited and relatively short shelf life. Thus, to determine the shelf life of the product, observations were made to estimate the shelf life using the acceleration method of critical moisture content approach. The variables used are initial moisture content, critical moisture content, equilibrium moisture content, slope of the ISA curve, packaging permeability, packaging area, solids weight per package, and saturated water vapor pressure at storage temperature. The initial moisture content value of purple sweet potato chips was 0,0103 g H2O/g solids, the critical water content value was 0,0287 g H2O/g solids, the equilibrium moisture content value increased with increasing relative humidity. The model chosen is the Henderson model because it has an R2 value of 0,9788 with the equation log(In(1/(1-aw))) = 0,6344+0,5446 In Me and a slope value of 0,1720. The best estimate on the shelf life of purple sweet potato chips is at 70% relative humidity storage using SNI critical water content, obtained in PP packaging for 31 days and aluminum foil for 123 days. Keyword: moisture content, purple sweet potato chips, relative humidity, shelf life
Keyword: moisture content, purple sweet potato chips, relative humidity, shelf life

Judul: Pendugaan Umur Simpan Tepung Bumbu Gorengan dengan Metode Akselerasi Pendekatan Kadar Air Kritis
Abstrak: Konsumsi tepung terigu semakin meningkat sebagai bahan penyalut produk gorengan. Namun, tepung terigu merupakan tepung yang mengandung gluten dan dapat menyebabakan beberapa penyakit jika konsumsinya berlebihan. Peran tepung terigu sebagai penyalut gorengan dapat digantikan dengan tepung bumbu non gluten. Sebagai produk pangan, tepung bumbu harus diketahui umur simpannya untuk keamanan konsumen. Pendugaan umur simpan dilakukan dengan metode Accelerated Shelf-Life Test (ASLT), dilakukan dengan memodifikasi suhu dan kelembaban ruang agar produk yang disimpan dapat cepat rusak. Pendugaan umur simpan tepung bumbu dilakukan dengan metode kadar air kritis menggunakan persamaan Labuza. Variabel yang digunakan antara lain kadar air awal, kadar air kritis, kadar air kesetimbangan, slope kurva ISA, permeabilitas kemasan, luas kemasan, berat padatan per kemasan, dan tekanan uap air jenuh pada suhu penyimpanan. Kurva ISA yang didapatkan pada penelitian berbentuk sigmoid atau sama dengan Kurva ISA tipe II yang banyak ditemukan pada produk pangan. Nilai Mean Relative Determination (MRD) terkecil pada pemodelan Hasley 3,74. Pendugaan umur simpan dilakukan pada RH 75, 84, dan 89% menggunakan kadar air kritis percobaan dan kadar air kritis berdasarkan Standar Nasional Indonesia (SNI) dengan beberapa jenis kemasan antara lain PP 02, PP 03, dan alumunium foil. Hasil perhitungan umur simpan tepung bumbu gorengan pada penyimpanan kelembaban relatif 75, 84, dan 89% menggunakan kadar air kritis SNI dengan kemasan PP 02 secara berturut-turut selama 95, 49, 35 hari, dengan kemasan PP 03 selama 143, 74, 54 hari, dan dengan kemasan alumunium foil selama 641, 333, 242 hari., Consumption of wheat flour is increasing as a coating of fried products. However, wheat flour is a flour that contains gluten and can cause some diseases if its consumption is excessive. The role of wheat flour as a fried coating can be replaced with non-gluten seasoning flour. As a food product, seasoning flour should be known its shelf life for consumer safety. Estimation of shelf life is done by Accelerated Shelf-Life Test (ASLT) method, done by modifying the room temperature and humidity conditions so that the stored products can be quickly damaged. Seasoning flour is a food product whose main damage is due to the absorption of water vapor. Estimating the shelf life of seasoning flour is done by critical water content method using Labuza equation. The parameters used include initial moisture content, critical moisture content, equilibrium water content, ISA curve slope, packaging area, packaging permeability, solid weight per package, and saturated water vapor pressure at storage temperature. The ISA curve obtained in the study is in the form of sigmoid or the same as the ISA curve type II that is found in food products. The smallest Mean Relative Determination (MRD) value is obtained in Hasley modeling 3,74. The restoration of shelf life was carried out at RH 75, 84, and 89% using experimental critical water content and critical water content based on the Indonesian National Standard (SNI) with several types of packaging including PP 02, PP 03, and aluminum foil. The results of the calculation of the shelf life of fried spice flour in the storage of relative humidity 75, 84, and 89% use the critical water content of SNI
Keyword: Kadar air, Kelembaban relatif, Tepung bumbu, Umur simpan

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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