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: Pelapisan Buah Manggis (Garcinia mangostana L.) dan Adaptasi Suhu terhadap Perubahan Karakteristiknya selama Penyimpanan
Abstrak: Mangosteen (Garcinia mangostana L.) as an exotic tropical fruit is the one commodity of fruits that have high economic value and popular society. The main factor that limits the export potential of the mangosteen fruit including the decline in fruit quality during storage.Constraints exporters mangosteen fruit is the speed of the next petal wilting is assumed as a decrease in quality by consumers that makes the decline in sales value. Efforts that have been done on the mangosteen fruit to reduce the granting of transpiration is beeswax, giberelic acid, benomyl or a combination. Other efforts also can be done is by storage at low temperatures. But these efforts also have the disadvantage that the temperature changes that occurred from ambient temperature to low temperature can affect the quality of mangosteen fruit, mangosteen, especially sepals which is a major factor in determining the quality mangosteen exports. For thar, there should be efforts and new technologies that can reduce the shock effect of this temperature so that the mangosteen will be in export quality and better durability. The purpose of this study was to determine the effect of coating the fruit mangosteen and adaptation temperature on its characteristics change during storage. Characteristics that were observed during storage is the physical properties (appearance of sepals, weight loss, skin color, and the level of violence). Based on the results of regression analysis to the treatment performed, to appearance of sepals, coating treatment without or with adaptation temperature kept at cold temperatures (8-10)°C shows the value of a relatively smaller slope (2,17987 and 2,17676) compared with coating treatment without or with adaptation temperature stored at room temperature (29-31)°C. This indicates that treatment with adaptation temperature coating on cold temperature storage has sepals damage level is lower than other treatments. For weight loss treatment characteristics without adaptation temperature coating that is stored at room temperature (29-31)°C and cold temperatures (8-10)°C showed slope values (0,00832 and 0,00162), relatively lower than those treated with adaptation temperature coating stored at room temperature (29-31)°C and cold temperatures (8-10)°C showed slope values (0,00628 and 0,00158).Based on these characteristics can be seen that treatment with adaptation temperature coating has a churn rate of weight loss is much smaller than without adaptation temperature coating treatment on the same storage temperature. Based on the parameters of the texture or hardness, for each treatment, such treatment without adaptation temperature coating that is stored at room temperature (29-31)°C, without adaptation temperature coating that is stored at cool temperatures (8-10)°C, with adaptation temperature coating stored at room temperature (29-31)°C and with adaptation temperature coating that is stored at cold temperature (8-10)°C showed slope values (0,0006049; 0,0002076; 0,0008072; 0,0002053). This showed that the mangosteen are given preferential treatment temperature adaptation that is iv stored in cold temperatures have a smaller increase in violence compared to other treatments. Mangosteen fruit shelf life stored at room temperature (29-31)°C lasted only 15 days, while the mangosteen that are stored at a temperature (8-10)°C can reach 35 days. The smallest percentage change in the characteristics contained in the mangosteen fruit mangosteen with the treatment
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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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