Judul: Effect of Ethephon on Ripe and Quality of Avocado (Persea americana Mill.)
Abstrak: Apokad (Persea americana Mill.) menjadi salah satu buah pilihan masyarakat karena memiliki rasa yang enak, kandungan antioksidan tinggi, kaya akan serat, dan nutrisi. Apokad merupakan buah klimakterik dimana proses pemasakannya akan terus berlangsung setelah buah dipanen dari pohon. Salah satu tantangan global yang harus dihadapi petani apokad saat ini adalah menawarkan produk kepada konsumen dengan tingkat kemasakan homogen. Penelitian ini bertujuan mengetahui karakteristik awal buah apokad, menemukan konsentrasi ethephon yang tepat dan efektif untuk mempercepat dan menyeragamkan kemasakan apokad serta mengetahui pengaruhnya terhadap mutu buah. Rancangan penelitian yang digunakan adalah rancangan kelompok lengkap teracak (RKLT) faktor tunggal berupa penambahan ethephon dengan konsentrasi 0, 500, dan 1000 ppm. Parameter yang diamati yaitu kadar air, kelunakan, edible portion, susut bobot, PTT, ATT, vitamin C, diameter, panjang, warna daging dan kulit buah yang diamati hingga 15 hari setelah perlakuan (HSP). Hasil penelitian menunjukkan ethephon dengan konsentrasi 500 ppm dapat mempercepat pemasakan 3 hari lebih cepat dibandingkan dengan perlakuan kontrol, serta dapat mempertahankan mutu lebih lama dibandingkan dengan perlakuan ethephon 1000 ppm sampai dengan 12 HSP., Avocado (Persea americana Mill.) is one of the people’s choice fruit because it has a good taste, high antioxidant contents, is rich in fiber and nutrients. Avocado is a climacteric fruit where the ripening process will continue after the fruit is harvested from the tree. One of the global challenges that avocado farmers have to face today is offering consumers products with homogeneous ripeness levels. This study objective is to determine the initial characteristics of avocados, obtain the appropriate and effective ethephon concentration to accelerate and uniform avocado ripening as well as determine its effect on fruit quality. The research design used was a single factor randomized complete block design in the form of ethephone concentrations of 0, 500, and 1000 ppm. The parameters observed were moisture content, softness, edible portion, weight loss, TSS, TTA, vitamin C, diameter, length, flesh and skin color of the fruit which were observed up to 15 days after treatment (DAT). The results showed that ethephon with a concentration of 500 ppm could accelerate ripening 3 days faster than the control treatment, and could maintain quality longer than the 1000 ppm ethephon treatment up to 12 DAT.
Keyword: climacteric, ethylene, metabolism, ripenesslevel, softness

Judul: Effect of Chitosan and Storage Temperature on the Postharvest Shelf life and Quality of Avocado (Persea americana Mill.)
Abstrak: Apokad (Persea americana Mill) biasanya dikonsumsi dalam keadaan segar, dapat dimakan ketika sudah masak (ripe). Dalam 100 g buah apokad mengandung energi sebanyak 167 kkal, protein 1,96 g, karbohidrat 8,64 g, kalsium 13 mg, magnesium 29 mg, fosfor 54 mg, vitamin E 1.97 mg, dan asam lemak total tak jenuh 9,8 g. Produksi buah apokad di Indonesia pada tahun 2018 sebesar 410 094 ton artinya naik 12,92% dari tahun 2017. Percobaan ini bertujuan mengetahui hubungan konsentrasi kitosan dan suhu simpan untuk memperpanjang umur simpan buah apokad. Percobaan ini menggunakan Rancangan acak kelompok dengan dua faktor yaitu suhu simpan dan konsentrasi kitosan. Suhu simpan terdiri atas dua taraf yaitu (17±1 oC) dan (13±1 oC) serta konsentrasi kitosan terdiri atas tiga taraf yaitu 0%, 2%, dan 4%. Pengamatan yang dilakukan yaitu pengamatan non destruktif dan pengamatan destruktif. Pengamatan non destruktif meliputi bobot buah, dan warna kulit buah, serta pegamatan destruktif meliputi padatan terlarut total, asam tertitrasi total, vitamin C, edible portion, kelunakan dan warna daging buah. Perlakuan kitosan 2% dan 4% dengan suhu simpan 13±1 oC memberikan pengaruh terhadap susut bobot, dan mempertahankan edible portion, kekerasan, PTT, warna daging dan warna kulit buah. Pelapisan kitosan 4% dengan suhu penyimpanan 13±1 oC dapat mempertahankan kualitas buah apokad selama 22 hari., Avocado (Persea americana Mill) is usually consumed fresh, can be eaten when it is ripe (ripe). In 100 g of avocado contains 167 kcal of energy, 1.96 g of protein, 8.64 g of carbohydrates, 13 mg of calcium, 29 mg of magnesium, 54 mg of phosphorus, 1.97 mg of vitamin E, and 9 total unsaturated fatty acids. 8 g. The production of avocados in Indonesia in 2018 was 410 094 tons, an increase of 12.92% from 2017. This experiment aims to determine the relationship between chitosan concentration and storage temperature to extend the shelf life of avocados. This experiment used a randomized block design with two factors, namely storage temperature and chitosan concentration. The temperature consisted of two levels, namely (17±1 ℃) and (13±1 ℃) and the concentration of chitosan consisted of three levels, namely 0%, 2%, and 4%. Observations made are non-destructive observations and destructive observations. Non-destructive observations included fruit weight and skin color, and destructive observations included total dissolved solids, total titrated acid, vitamin C, edible portion, softness and color of fruit flesh. The treatment of 2% and 4% chitosan with a temperature of 13±1 ℃ gave an effect on weight loss, and maintained edible portion, hardness, PTT, flesh color and fruit skin color. Coating with 4% chitosan with a storage temperature of 13±1 ℃ can maintain the quality of avocados for 22 days.
Keyword: avocado, chitosan, destructive, non-destructive, 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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