Judul: Optimasi Formula dan Proses Ekstrusi Ubi Jalar Ungu dengan Response Surface Methodology
Abstrak: Ubi jalar ungu (Ipomoea batatas var. Ayamurasaki) sebagai salah satu komoditas pertanian yang unggul karena warnanya yang menarik, mudah didapat, dan manfaat kesehatannya. Industri keripik ubi jalar hanya menggunakan ubi jalar dengan ukuran tertentu. Petani pun terkena imbas karena penyerapan hasil panen oleh industri tidak maksimal. Pengolahan ubi jalar ungu menjadi produk olahan menggunakan ekstruder pada skala industri masih belum dapat ditemui. Penelitian ini bertujuan untuk menentukan formula dan parameter proses ekstrusi ubi jalar ungu yang optimum untuk menghasilkan produk dengan karakteristik mutu yang baik. Ubi jalar ungu yang diolah dengan teknik ekstrusi menggunakan ekstruder ulir ganda pemasak (BEX-DS-2256). Optimasi formula dan proses dilakukan menggunakan Response Surface Methodology (RSM) dengan rancangan Combine D-Optimal pada program Design Expert 12.0. Percobaan dilakukan dengan 22 perlakuan yang merupakan kombinasi faktor-faktor konsentrasi ubi jalar ungu (60–70%), tepung tapioka (20–25%), tepung ubi jalar ungu (10–15%), dan suhu ekstrusi (60–70 oC). Perlakuan yang optimum adalah dengan konsentrasi ubi jalar ungu 62.66%, tepung tapioka 22.34%, tepung ubi jalar ungu 15%, dan suhu ekstrusi 62.53 oC. Kombinasi formula dan proses tersebut menghasilkan adonan ubi jalar ungu dengan kadar air 49.34% (bb), kelengketan 711.67 gf, dan derajat gelatinisasi 52.06% dengan nilai desirability 0.76., Purple sweet potato (Ipomoea batatas var. Ayamurasaki) is one of the leading agricultural commodities due to its attractive color, availability, and health benefits. The sweet potato chip industry only uses sweet potatoes of a certain size. Farmers are also affected because the absorption of crops by the industry is not optimal. The development process of turning purple sweet potatoes into processed products using industrial scale extruders is still can’t be found. This study aimed to determine the optimum formula and extrusion process of the purple sweet potato to produce a product with good quality characteristics. Purple sweet potato was processed by extrusion technique using a double screw extruder (BEX-DS-2256). The optimization of formulas and processes was carried out using the Response Surface Methodology (RSM) with the Combine D-Optimal design in the Design Expert 12.0 program. The experiment conducted 22 treatments that were a combination of purple sweet potato concentration (60–70%), tapioca flour (20–25%), purple sweet potato flour (10–15%), and extrusion temperature (60–70 oC). The optimum treatment was with a concentration of 62.66% purple sweet potato, 22.34% tapioca flour, 15% purple sweet potato flour, and an extrusion temperature of 62.53 oC. The combination of these formulas and processes resulted in purple sweet potato dough with a moisture content of 49.34% (bb), stickiness of 711.67 gf, and degree of gelatinization of 52.06% with a desirability value of 0.76.
Keyword: derajat gelatinisasi, ekstruder, kelengketan, optimasi, ubi jalar ungu

Judul: The Study of Frying Process on the Characteristics of Purple Sweet Potato (Ipomoea batatas L.) Simulated Chips
Abstrak: Umbi ubi jalar berukuran kecil sering kali tidak memenuhi spesifikasi industri dan tidak laku dijual, sehingga pemanfaatannya rendah dan menimbulkan masalah kehilangan hasil panen. Teknologi pengolahan keripik simulasi menawarkan solusi pemanfaatan umbi berukuran kecil melalui proses pengadonan, pembentukan lembaran, dan pencetakan. Keripik simulasi dimasak melalui penggorengan, satuan operasi kompleks yang memengaruhi karakteristik keripik yang dihasilkan. Penelitian ini bertujuan mendapatkan proses penggorengan yang menghasilkan keripik simulasi ubi jalar ungu yang paling disukai oleh panelis. Percobaan dilakukan menggunakan rancangan acak lengkap (RAL) dengan perlakuan kombinasi kadar air sebelum penggorengan (basah; kering) dan kondisi penggorengan (160 oC, 1 menit; 175 oC, 25 detik; 190 oC, 10 detik). Karakter produk yang dianalisis adalah kadar air, warna, tekstur, dan skor kesukaan konsumen pada uji organoleptik. Keripik terbaik ditentukan berdasarkan skor kesukaan atribut overall tertinggi. Keripik terbaik memperoleh skor kesukaan overall 5,00 dan memperoleh skor atribut aroma 5,02; warna 4,21; rasa 4,84; dan tekstur 5,14 dari skala hedonik 7-poin yang menunjukkan panelis netral hingga agak suka terhadap keripik. Keripik terbaik adalah keripik yang sebelumnya dikeringkan selama 1,5 jam menghasilkan adonan basah dengan kadar air 15%, kemudian digoreng pada suhu 175 oC selama 25 detik. Keripik simulasi ubi jalar ungu memiliki kandungan proksimat protein 1,24%; air 1,63%; abu 2,81%; lemak 22,36%; dan karbohidrat 71,97% dengan nilai kalori 493,16 kkal per 100 g produk. Keripik simulasi ubi jalar ungu memiliki aktivitas antioksidan dinyatakan sebagai IC50 sebesar 5688,61 ppm. Antosianin dan senyawa fenolik lain dalam ubi jalar ungu segar terdegradasi selama pengolahan, sehingga aktivitasnya sebagai antioksidan di dalam produk keripik simulasi lebih rendah apabila dibandingkan dengan ubi jalar ungu segar., Small sweet potato tubers often do not meet industrial specifications and cannot be sold, resulting in low utilization and causing crop loss problems. Simulated chips processing technology offers a solution for utilizing small tubers through kneading, sheet forming, and shaping processes. Simulated chips were cooked through frying, a complex unit operation that affects the characteristics of the products. This study aimed to obtain the frying process which produced the most liked sweet potato chips according to panelists. The experiment was conducted based on a completely randomized design (CRD) with water content before frying (wet; dry) and frying conditions (160 oC 1 minute; 175 oC 25 seconds; 190 oC 10 seconds) as treatments. The observed responses were water content, color, texture, and consumer preference scores on organoleptic tests. The best chips were determined based on the highest overall attribute preference score. The best chips obtained an aroma attribute score of 5,02; color 4,21; taste 4,84; and texture 5,14 from a 7-point hedonic scale, indicating panelists felt neutral to moderately liked the chips. The best chips were first dried for 1,5 hours to produce a wet dough with a moisture content of 15%, then fried at a temperature of 175 oC for 25 seconds. Purple sweet potato simulated chips had a proximate protein content of 1,24%; water 1,63%; ash 2,81%; fat 22,36%; and carbohydrates 71,97% with a caloric value of 493,16 kcal per 100 g of product. The chips had antioxidant activity expressed as IC50 of 5688,61 ppm. Anthocyanins and other phenolic compounds
Keyword: characteristics, frying, purple sweet potato, simulated chips, karakteristik, keripik simulasi, penggorengan, ubi jalar ungu

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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