Judul: Optimization Gelatin Extraction Process for Catfish (Pangasius sp.) Skin with Response Surface Methodology Application
Abstrak: Ikan patin merupakan bahan baku gelatin alternatif yang aman dan halal. Kulit ikan memiliki karakteristik yang berbeda dengan hewan terestrial sehingga memerlukan optimasi pada proses ekstraksi sebelum masuk ke skala industri. Penelitian ini bertujuan melakukan optimasi kondisi pretreatment pada proses ekstraksi gelatin menggunakan Response Surface Methodology (RSM) serta menentukan karakteristik gelatin terpilih. Rancangan eksperimen yang digunakan yaitu Central Composit Design (CCD) dengan dua variabel bebas (konsentrasi NaOH dan konsentrasi asam asetat) dan 7 variabel respon (rendemen, kadar air, kadar abu, kekuatan gel, viskositas, pH, dan setting point). Hasil optimasi diperoleh respon optimum pada konsentrasi NaOH 0,3 M dan konsentrasi asam asetat 0,067 M. Hasil validasi keadaan optimal memperoleh gelatin terpilih dengan rendemen 22,44±0,68%, kadar air 8,53±3,4%, kadar abu 0,325±0,22%, derajat keasaman (pH) 6,65±0,13, kekuatan gel 241,58±9,5 Bloom, viskositas 6,65±0,5 mPas, dan setting point 19,75±1,06 ℃. Karakteristik gelatin terpilih telah memenuhi standar gelatin SNI 8622:2018 dan GMIA 2019., Catfish is an alternative raw material for gelatin that is halal and safe. Pangasius skin has different characteristics from terrestrial animals, so it requires to optimize the extraction process before industrial scale production. This study aims to optimize the pretreatment conditions in the gelatin extraction process using the Response Surface Methodology (RSM) and determine the characteristics of the selected gelatin based on the pretreatment conditions. Central Composite Design (CCD) with two independent variables (NaOH concentration and acetic acid concentration) and 7 response variables (yield, moisture content, ash content, gel strength, viscosity, pH, and setting point) was performed. The results showed the optimum response at 0.3 M NaOH and 0.067 M acetic acid. The validation obtained selected gelatin with a yield 22.44 ± 0.68%, water content 8.53 ± 3.4%, ash content 00.325 ± 0.22%, degree of acidity (pH) 6.65 ± 0.13, gel strength 241.58 ± 9.5 Bloom, viscosity 6.65 ± 0.45 mPas, and setting point 19.75 ± 1.06 ℃. The characteristics of the selected gelatin have met the SNI 8622: 2018 and GMIA 2019 gelatin standards.
Keyword: catfish, gelatin, halal, process optimization, RSM

Judul: Effect of Citrict Acid Soaking Volume and Time on Catfish Skin for Optimazion of Gelatin Extraction
Abstrak: Gelatin berasal dari protein kolagen yang diperoleh melalui hidrolisis kolagen kulit dan tulang hewan yang dapat dimanfaatkan sebagai bahan baku pembuatan kapsul keras. Penelitian dilakukan untuk mendapatkan formula proses pembuatan gelatin optimal dari kulit ikan patin dengan Response Surface Methodology (RSM) serta dilakukan analisis fisik dan kimia kapsul keras gelatin. Rancangan eksperimen yang digunakan yaitu Central Composite Design (CCD) yang terdiri dari dua variabel yaitu volume asam sitrat (300 mL, 400 mL dan 500 mL) dan waktu perendaman asam sitrat (6 jam, 12 jam dan 18 jam) pada suhu ekstraksi 65°C selama 8 jam dengan delapan respon yaitu rendemen, kadar air, kadar abu, pH, kekuatan gel, viskositas, setting point dan melting point. Ekstraksi gelatin optimal pada perlakuan volume 500 mL dan waktu perendaman 18 jam menghasilkan gelatin dengan kualitas yang telah sesuai standar GMIA 2019 dan SNI 86222018. Nilai validasi keadaan optimal yang diperoleh yaitu rendemen 22,41±0,20% kadar air 6,72±0,40%; kadar abu 0,30±0,05%; pH 5,26±0,02; kekuatan gel 266,08±14,68 bloom; viskositas 59±0,16 mps; setting point 20,33±1,5°C; dan melting point 24,67±1,52°C. Karakteristik kapsul keras yang dihasilkan telah sesuai dengan standar Depkes RI 1995., Gelatin is derived from collagen protein obtained through hydrolysis of animal skin and bone collagen which can be used as raw material for making hard capsules. The research was conducted to obtain the optimal formula for the process of making gelatin from catfish skin with Response Surface Methodology (RSM) and physical and chemical analysis of hard gelatin capsules were carried out. The experimental design was the Central Composite Design (CCD) which consisted of two variables, namely the volume of citric acid (300 mL, 400 mL and 500 mL) and the immersion time of citric acid (6 hours, 12 hours and 18 hours) at an extraction temperature of 65°C for 8 hours with eight responses, namely yield, water content, ash content, pH, gel strength, viscosity, setting point and melting point. Optimal gelatin extraction at treatment volume of 500 mL and soaking time of 18 hours produced gelatin with quality that complies with GMIA 2019 and SNI 8622-2018 standards. The optimal validation value obtained was yield of 22,41±0,20% water content 6,72±0,40%; ash content 0,30±0,05%; pH 5,26±0,02; gel strength 266,08±14,68 bloom; viscosity 59±0,16 mps; setting point 20,33±1,5°C; and a melting point of 24,67±1,52°C. The characteristics of the hard capsules produced are in accordance with the 1995 Ministry of Health standards.
Keyword: Catfish, Gelatin, Hard capsule, Optimal, Response Surface Methodology

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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