Judul: Study of Terigas Tangerine Degreening Originate from Sambas Regency of West Kalimantan
Abstrak: Terigas tangerine peel is still green even when it has reached acceptable internal maturity, meanwhile the green peel indicated immature fruit. Improving tangerine uniform yellow peel will also improve its aesthetic quality and price which could be taken by ethylene degreening technique. The objectives of this research were: (1) to study the ethylene concentration and trigger time of Terigas tangerine (Citrus nobilis var. chrysocarpa) degreening process, (2) to investigate influences of degreening on physicochemical and organoleptic changes of Terigas tangerine, (3) to determine the best ethylene consentration and trigger time of Terigas tangerine degreening process. Initial tangerine quality were analyzed before the tangerine were arranged inside box layered by LLDPE 0.06 mm plastic. After that the plastic was closed with the top of box remained open. Each box contained of 3 kg tangerines which finally exposed by 1000, 1500, and 2000 ppm of exogenous ethylene and without ethylene (control), with trigger time for 10, 20, and 30 hours. Soon after each trigger time was reached, the plastic was then opened and tangerines were placed at room temperature until their peel turned to be yellow. After that, quality of tangerines were analyzed which consisted of color changes, firmness, juice misture content, pH value, vitamin C content, total of chlorophyll and carotenoid, total soluble solid, and organoleptic. Results of the research showed that ethylene enhanced color of tangerine, increased total of carotenoid, and decreased total of chlorophyll. However it did not affect internal quality such as moisture content, firmness, total soluble solid, and vitamin C. Postharvest degreening also increased panelists preference of tangerine external color, nevertheless it did not affect sweetness, texture, and aroma of Terigas tangrine. The best treatment was 1000 ppm ethylene with trigger time for 30 hours. Uniform yellow peel of Terigas tangerine occured on the fourth day of storage at room temperature.
Keyword: tangerine, degreening, ethylene, trigger time, physicochemical

Judul: egreening of siam tangerine on different ethylene exposure time and temperature. Supervised by Y ARIS PURWANTO and ROEDHY POERWANTO.
Abstrak: Jeruk siam pada umumnya berwarna hijau. Teknologi degreening yang tepat dapat memperbaiki warna kulit jeruk tropika menjadi jingga secara merata. Degreening merupakan proses perombakan pigmen hijau (klorofil) pada kulit jeruk secara kimiawi dan membentuk warna kuning atau jingga (karotenoid) tanpa mempengaruhi kualitas internal buah. Tujuan dari penelitian ini adalah untuk mengkaji pengaruh durasi pemaparan etilen dan suhu degreening untuk memunculkan warna jingga pada jeruk siam. Etilen 200 ppm diinjeksikan ke dalam box degreening yang berisi jeruk sebanyak 2.8 kg dan dipaparkan pada cooling chamber dengan suhu 15, 20 dan 25 oC selama 0, 24, 48 dan 72 jam.Pemaparan etilen dilakukan dengan metode single shot dan multiple shot. Setelah pemaparan, jeruk kemudian disimpan pada suhu ruang. Pengamatan dilakukan setiap dua hari: (a) pengamatan non-destruktif dilakukan dengan menggunakan color reader dan metode citrus color chart (CCC)untuk mengetahui perubahan warna; (b) pengamatan destruktif dilakukandengan mengukur kandungan klorofil dan karotenoid serta mengukur kekerasan,TPT, TAT dan vitamin C untuk mengetahui perubahan fisikokimia jeruk. Hasil penelitian menunjukkan durasi pemaparan terbaik pada jeruk siam Jember dan Banyuwangi adalah selama 48 jam pada suhu 20 oC. Durasi pemaparan dan suhu terbaik dapat mengubah nilai CCI dari -0.60 menjadi 6.55 pada jeruk siam Jember dan pada jeruk siam Banyuwangi -0.33 menjadi 9.41. Pada jeruk siam Jember warna optimum yang dihasilkan adalah kuning sedangkan jeruk siam Banyuwangi adalah jingga cerah. Degreening dapat mengubah warna jeruk menjadi jingga cerah dan tidak memberikan pengaruh negatif terhadap kualitas internal buah., Siam Tangerine peel is green. Degreening technology can improve the citrus peel color becomes uniformly orange. Degreening is a process to break down green pigment (chlorophyll) on citrus peel chemically and form the orange color (carotene) without affecting internal quality of fruit. The purpose of this study was to determine the effect of ethylene exposure duration and temperature to bring out the color on siam tangerine. Ethylene 200 ppm was injected into the box containing 2.8 kg citrus and was exposed to the cooling chamber with a temperature of 15, 20 or 25 °C for 0, 24, 48 or 72 hours. Ethylene exposure was conducted using multiple shots method. After exposure, tangerine were put at room temperature condition. Observations were conducted every two days: (a) non-destructive observation conducted using color reader and CCC method to determine the color changes; (b) destructive observations for measuring chlorophyll and carotenoids content and physico-chemical changes i.e. firmness, soluble solid content, titratable acidity and vitamin C. The results showed that the best combination was 48 hours ethylene exposure duration at 20 oC both for siam Jember, as well as siam BanyuwangiThis degreening technique alter the CCI value from -0.60 to be 6.55 in siam Jember, and from -0.33 to be 9.41 in siam Banyuwangi, that was changed the tangerines into a yellow of siam Jember and bright orange of siam Banyuwangi. Degreening has not negative impact for internal quality.
Keyword: Carotenoid, Chlorophyll, Citrus color chart, Citrus color index, Cooling chamber, Tropical citrus, Degreening technology, Green pigment, Fruit quality, Ethylene exposure, Siam Jember, Siam Banyuwangi, Internal quality

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.
Keyword: