Judul: Application of Carrageenan and Antimicrobial Edible Coating to Extend the Self Life of Tomatoes (Lycopersicum esculentum)
Abstrak: Buah tomat (Lycopersicum esculentum) merupakan produk hortikultura yang memiliki banyak manfaat serta kaya akan vitamin, mineral, dan serat gizi. Tomat tergolong buah yang memiliki kadar air yang tinggi dan juga mudah terserang mikroorganisme perusak. Mikroorganisme perusak berupa kapang Alternaria penyebab penyakit bercak-bercak cokelat atau menghitam pada permukaan kulit tomat. Pemanfaatan edible coating karagenan dengan penambahan senyawa antimikroba diharapkan mampu menghambat perkembangan mikroorganisme dan memperpanjang umur simpan tomat. Penelitian ini bertujuan mengkaji dan menentukan efektifitas pengaruh aplikasi edible coating berbahan dasar karagenan dengan penambahan senyawa antimikroba terhadap mutu buah tomat selama penyimpanan. Tahap penelitian terdiri dari persiapan sampel, pembuatan larutan coating, pengaplikasian coating, dan pengamatan selama 28 hari. Jenis karagenan yang digunakan ialah Kappa-karagenan dengan penambahan antimikroba berupa asam askorbat (C6H8O6) dan zink oksida (ZnO). Hasil penelitian menunjukkan perlakuan coating dengan penambahan senyawa antimikroba berupa asam askorbat (KGA) dan zink oksida (KGZ) merupakan perlakuan terbaik yang mampu mempertahankan parameter respirasi, pH, aktivitas air (aw), susut bobot, kadar air, vitamin C, total padatan terlarut, total asam, kekerasan, dan intensitas warna pada hari ke-28. Hasil analisa total plate count (TPC) memiliki nilai yang sama pada hari ke-20 untuk perlakuan dengan penambahan antimikroba sebesar 3,4x105 koloni/g dengan ambang batas SNI sebesar 105 koloni/g dibandingkan dengan perlakuan tanpa coating yang bertahan selama 12 hari., Tomato fruit (Lycopersicum esculentum) is a horticultural product that has many benefits and rich vitamins, minerals, and nutritional fiber. Tomatoes are classified as fruits that have high water content and are also susceptible to damaging microorganisms. Damaging microorganisms in the form of mold Alternaria cause disease, brown or blackened spots on the surface of tomato skin. The use of edible carrageenan coating with the addition of antimicrobial compounds is expected to inhibit the development of microorganisms and extend the shelf life of tomatoes. This study aims to examine and determine the effectiveness of the effect of edible coating application made from carrageenan with the addition of antimicrobial compounds on the quality of tomatoes during storage. The research phase consists of sample preparation, making coating solutions, applying coatings, and observing for 28 days. The type of carrageenan used is kappa-carrageenan with the addition of antimicrobials in the form of ascorbic acid (C6H8O6) and zinc oxide (ZnO). The results showed that coating treatment with the addition of antimicrobial compounds in the form of ascorbic acid (KGA) and zinc oxide (KGZ) is the best treatment that can maintain parameters of respiration, pH, water activity (aw), weight loss, water content, vitamin C, total dissolved solids, total acid, hardness, and color intensity on day 28. The results of total plate count (TPC) analysis had the same value on day 20 for treatment with the addition of antimicrobials of 3,4x105 colonies/g with an SNI threshold of 105 colonies/g compared to uncoated treatment that lasted for 12 days.
Keyword: asam askorbat, buah tomat, mikroorganisme, coating, zink oksida

Judul: Penggunaan Pelapisan Kitosan dan Penyimpanan Dingin untuk Mempertahankan Mutu Tomat Ceri (Lycopersicum esculentum var. cerasiforme)
Abstrak: Tomat ceri mudah mengalami penurunan mutu selama penyimpanan. Teknologi penanganan pascapanen yang tepat diperlukan guna mempertahankan mutu tomat ceri. Penelitian ini bertujuan mengkaji pengaruh pelapisan kitosan dan suhu penyimpanan terhadap mutu tomat ceri serta menentukan konsentrasi pelapisan kitosan dan suhu penyimpanan yang terbaik untuk mempertahankan mutu tomat ceri. Bahan yang digunakan dalam penelitian ini adalah tomat ceri varietas Fortesta yang diperoleh dari Lima Sukses Utama Farm, Kabupaten Bogor. Pelapisan menggunakan kitosan dengan bahan tambahan berupa akuades dan asam asetat. Tomat ceri dicelupkan pada larutan kitosan dengan konsentrasi 1% dan 2% dan sebagai kontrol adalah tomat ceri tanpa pelapisan. Masing-masing kelompok tomat ceri kemudian disimpan pada suhu 15 °C dan 25 °C. Parameter yang diamati selama penyimpanan adalah laju respirasi, susut bobot, kekerasan, total padatan terlarut, uji organoleptik (kesegaran, warna, dan aroma) pada tomat ceri. Rancangan percobaan yang digunakan adalah rancangan acak lengkap faktorial dengan dua faktor, yaitu pelapisan kitosan (1%, 2%, dan kontrol) dan suhu penyimpanan (15 °C dan 25 °C). Data diolah menggunakan analisis sidik ragam (Anova) dan uji lanjut Duncan. Hasil penelitian menunjukkan bahwa pelapisan kitosan berpengaruh terhadap laju respirasi, susut bobot, kekerasan, total padatan terlarut, dan uji organoleptik. Suhu penyimpanan berpengaruh terhadap laju respirasi, susut bobot, kekerasan, total padatan terlarut, dan uji organoleptik. Pelapisan dengan konsentrasi kitosan 2% dan suhu penyimpanan 15 °C merupakan perlakuan terbaik yang mampu menekan laju respirasi, susut bobot, kekerasan, total padatan terlarut, dan secara organoleptik masih diterima panelis pada hari penyimpanan ke-21. Sedangkan pada kontrol hanya bertahan pada hari penyimpanan ke-15., Cherry tomatoes are prone to quality deterioration during storage. Proper post-harvest handling technology is needed to maintain the quality of cherry tomatoes. This research aims to examine the effect of chitosan coating and storage temperature on the quality of cherry tomatoes and determine the optimal chitosan coating concentration and storage temperature to maintain the quality of cherry tomatoes. The materials used in this research were Fortesta variety cherry tomatoes obtained from Lima Sukses Utama Farm, Bogor Regency. Coating using chitosan with additional materials of distilled water and acetic acid. Cherry tomatoes were dipped in chitosan solution with concentrations of 1% and 2%, and the control was cherry tomatoes without coating. Each group of cherry tomatoes was then stored at temperatures of 15 °C and 25 °C. Parameters observed during storage were respiration rate, weight loss, firmness, total soluble solids, and organoleptic tests (freshness, color, and aroma) of cherry tomatoes. The experimental design used was a factorial completely randomized design with two factors, namely chitosan coating (1%, 2%, and control) and storage temperature (15 °C and 25 °C). Data were analyzed using analysis of variance (Anova) and Duncan's multiple range test. The results showed that chitosan coating affects the respiration rate, weight loss, firmness, total soluble solids, and organoleptic tests. Storage temperature affects respiration rate, weight loss, firmness, total soluble solids, and organoleptic tests. Coating with 2% chitosan concentration and storage temperature of 15 °C were the best treatments that were able to suppress respiration rate, weight loss, firmness, total soluble solids, and were still acceptable organoleptically by panelists on the 21st day of
Keyword: cherry tomatoes, chitosan coating, quality, storage temperature

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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