Judul: Perubahan Kekerasan, Kadar Pektin, dan Aktivitas Poligalakturonase Kulit Buah Manggis (Garcinia mangostana L) pada Penyimpanan
Abstrak: Texture from fruits influenced by cell wall components, one of this is pectin. The purpose of this research was known alteration hardness, content pectin, calcium pectate and poligalacturonase activity of mangosteen perikarp during storage. Mangosteen divided into two groups, one group storage at room temperature and the others at 15ºC. Then fruits was analyzed its hardness with rheometer, content of pectin and calcium pectate with gravimetric method. Poligalcturonase activity analyzed by spectrophotometer in wavelength 530 nm. The hardness of mangosteen perikarp which storage at room temperature and 15ºC at day 20nd were 0.66 Kgf and 0.40 Kgf. The content of mangosteen perikarp pectin which storage at room temperature and 15ºC at day 20nd were 7.44% and 6.96%. The content of mangosteen perikarp calcium pectate which storage at room temperature and 15ºC at day 20nd were 1.69% and 1.48%. Poligalacturonase activity of mangosteen perikarp which storage at room temperature and 15ºC at day 20nd were 18.52 μmol/L/mnt and 19.01 μmol/L/mnt. The hardness of mangosteen perikarp had correlation very weak toward the content of pectin, calcium pectate, and polygalacturonase activity.
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Judul: Physiological study of hardening and color changes of pericarp in relation to climacteric respiration and moisture content in mangosteen (Garcinia mangostana) after harvest
Abstrak: Mangosteen is a high economic value fruit in Indonesia. The problems encountered are the fruit pericarp quickly harden and the color immediately changed to dark purple-black, and sepals quickly turned into brown in color after harvest, so shelf life is short, especially at room temperature. This research aimed to study the process of change in hardness, pericarp and sepal color, and the sepal freshness of the mangosteen fruit and the factors that influence the physiology and biochemistry during storage. The research consisted of five experiments: (1) hardening physiology of mangosteen pericarp, (2) effect of exogenous ethylene and storage temperature on quality changes of mangosteen, (3) effects of 1-methylcyclopropene (1-mcp) and storage temperature on hardening of and color change of pericarp of mangosteen, (4) Effect of cytokinin and CoSO4 on physical quality of mangosteen during cool storage, and (5) Effect of coating material and cytokinin CPPU (N-(2-chloro-4-pyridyl)-N-phenylurea (Forchlorfenuron)) on the quality of mangosteen on cool storage. The results showed that the peak rate of ethylene production one day earlier than the respiration climacteric. The peak rate of ethylene production occurred on day 11 while the respiration climacteric peak occurred on day 12. Climacteric respiration will lead to biochemical changes in the mangosteen fruit pericarp, such an increase in protein content, increased activity of the enzyme phenylalanine ammonia lyase (PAL), cinnamyl alcohol dehydrogenase (CAD), and peroxidase (POD), and increasing the amount of lignin. Pericarp hardening occured due to water content decrease in the mangosteen and increased content of lignin. Fruit stored at a temperature of 15oC can last up to 28 days after treatment (DAT). Whereas fruit stored at room temperature only last up to 14 DAT. Mangosteen fruit stored at a temperature of 15oC had lower level of resistance and hardness. had a higher water content, lower weight loss, slower color change, and had a higher total soluble solids (TSS) and titratable acidity (TA). Exogenous ethylene treatment did not provide a marked influence on all the variables observed, which means that the mangosteen fruit wass less sensitive to exogenous ethylene treatment. 1-MCP treatment at various doses did not prolong the shelf life of the mangosteen fruit. This treatment is consistent in both room temperature and at a temperature of 15oC. 6% beeswax better reduce weight loss than other types of coating materials.
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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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