Judul: Perubahan Warna Kulit Buah Tiga Varietas Jeruk Keprok dengan Perlakuan Degreening dan Suhu Penyimpanan
Abstrak: Color is the main quality that determines the level of demand for citrus. Consumer prefers orange citrus, whereas green citrus have high productivity in Indonesia. It causes local citrus cannot compete with imported citrus. One way that can make local citrus compete with imported citrus is by degreening. This is research was conducted to study the effect of degreening and storage temperature on color changes of tangerine peel. Research was conducted from June until July 2013 at the Laboratory of Center for Tropical Horticulture Studies, IPB. This study was conducted on 3 varieties of tangerines (Chokun, Fremont, and Batu 55) separately. This research used a randomized complete factorial design group 2 factors with 3 replications. The first factor is degreening temperature (18°C and room temperature) and second factor is storage temperature (18°C and room temperature). The results showed that degreening treatment at 18°C and room temperature storage on all three varieties of tangerines have the highest CCI value at 15 HSP.
Keyword: value of Citrus Color Index., storage temperature, orange, degreening temperature

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: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
Keyword: