Judul: Effect of NaOH Comparison on Patin Skin Pretreatment (Pangasius hypophthalamus) on Gelatin and Its Application on Hard Capsule Shells
Abstrak: Kulit ikan patin sangat potensial menjadi sumber gelatin, namun proses pretreatment yang dilakukan belum maksimal. Penelitian ini bertujuan menentukan perbandingan NaOH dan sampel dalam proses preatreatment, serta karakteristik fisik-kimia gelatin kulit ikan patin. Metode yang dilakukan yaitu Rancangan Acak Lengkap dan uji lanjut Duncan. Karakteristik gelatin yang telah sesuai dengan standar GMIA 2019 dan SNI 8622-2018. Perlakuan terbaik didapatkan pada perlakuan perbandingan 1:8 (b/v). Perlakuan tersebut menghasilkan rendemen 22,66 ± 1,07%; pH 6,43 ± 0,14; viskositas 67,5 ± 1,50 mps; dan kekuatan gel 244,143 ± 1,69 bloom. Perlakuan tersebut diaplikasikan dalam pembuatan cangkang kapsul keras. Karakteristik cangkang kapsul keras yang dihasilkan telah sesuai dengan standar Departemen Kesehatan RI (2020). Analisis histologi menunjukkan bahwa perlakuan yang digunakan belum mampu menghancurkan lapisan stratum compactum, sehingga perlu dilakukan treatment dengan cara lain agar rendemen gelatin yang dihasilkan maksimal., Pangasius skin has the potential to be a source of gelatin, but the process of pretreatment is not optimal. The purpose of this research was to determine the ratio of NaOH and samples in the process of the pre-treatment, as well as physicochemical characteristics of gelatin from catfish skin. The method used was Completely Randomized Design and Duncan's further test. Gelatin characteristics that are in accordance with the GMIA 2019 standard and SNI 8622-2018. The best treatment was obtained at a 1:8 (w/v) comparison treatment. This treatment resulted in a yield of 22.66 ± 1.07%; pH 6.43 ± 0.14; viscosity 67.5 ± 1.50 mps; and gel strength 244.143 ± 1.69 bloom. This treatment was applied in the manufacture of hard capsule shells. The characteristics of the hard capsule shell produced meet the standards of the Indonesian Ministry of Health (2020). Histological analysis showed that the treatment used had not been able to destroy the layer stratum compactum, so it was necessary to do other treatments in order to maximize the yield of gelatin.
Keyword: catfish, gelatin, hard capsule, NaOH, pretreatment

Judul: Effect of Acid Soaking Time on Characteristics of Pangasius Fish Skin Gelatin and Its Utilization for Hard Capsules
Abstrak: Kulit ikan patin merupakan bahan baku alternatif yang lebih ekonomis, aman, dan halal untuk pembuatan gelatin. Penelitian ini bertujuan menentukan pengaruh waktu perendaman dalam asam terhadap karakteristik gelatin serta menentukan karakteristik kapsul keras yang dihasilkan. Waktu yang digunakan pada proses perendaman asam yaitu 2, 3, dan 4 jam. Hasil analisis karakteristik gelatin menggunakan ANOVA menunjukkan bahwa perlakuan waktu perendaman asam tidak berpengaruh nyata terhadap karakteristik gelatin. Perlakuan yang diberikan menghasilkan rendemen 19,04-21,49%; kekuatan gel 190,013-234,6 bloom; viskositas 6,94-7,45 cP; derajat keasaman (pH) 5,94-6,205; kadar air 5,3727,824%; kadar abu 0,303-0,836%; setting point 18,67-22,33 ℃, serta tidak terdeteksi adanya logam berat. Karakteristik gelatin yang dihasilkan telah sesuai dengan standar GMIA 2019 dan SNI 8622-2018. Karakteristik kapsul yang dibuat dari bahan baku gelatin kulit ikan telah memenuhi standar kapsul menurut Kementerian Kesehatan Republik Indonesia., Pangasius fish skin is an alternative raw material that is more economical, safe and halal for the manufacture of gelatin. This study aims to determine the effect acid soaking time on the characteristics of the gelatin and to determine the characteristics of the resulting hard capsules. The time used in the soaking acid process is 2, 3, and 4 hours. The analysis result of the gelatin characteristics using ANOVA showed that the acid soaking time did not significantly affect the characteristics of gelatin. The treatment given resulted yields 19.04-21.49%; gel strength 190.013-234.6 bloom; viscosity 6.94-7.45 cP; degree of acidity (pH) 5.946.205; water content 5.372-7.824%; ash content 0.303-0.836%; setting point 18.6722.33 ℃, and no heavy metals were detected. The characteristics of the resulting gelatin comply with GMIA 2019 and SNI 8622-2018 standards. The characteristics of capsules made from fish skin gelatin have met capsule standards according to the Ministry of Health of the Republic of Indonesia.
Keyword: acetic acid, capsule, gelatin, pangasius

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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