Judul: Karakteristik rheologi gel cincau hitam (Mesona palustris BL)
Abstrak: Black grass jelly or often called as black jelly (“cincau” in Indonesian) was produced by boiling parts of black grass jelly plant to get the extract of black jelly. These parts include roots, stems, and leaves. Prior to boiling tapioca is added to the extract in order to set a gel after heating. Every part of black grass jelly plant produces different extract from other parts. The concentration of tapioca is important to get a self – standing black grass jelly. The aim of this research is to investigate the rheological characteristics of black grass jelly produced from every part of black grass jelly plant. The rheological characteristics are measured by viscosity test, uniaxial compression test, puncture test, and relaxation test. Black grass jelly from leaves extract has a higher viscosity than black grass jelly from roots and stems extracts. The engineering stresses obtained from uniaxial compression tests of black grass jelly produced from roots, stems, and leaves extracts were 43.02 (±27.94) kPa, 12.95 (±5.71) kPa, and 389.98 (±168.77) kPa, respectively. Those values were equal to true stresses of 5.43 (±3.51) kPa, 1.33 (±0.59) kPa, and 50.85 (±21.15) kPa, respectively. The stress values from puncture test of black grass jelly (4% b/v tapioca/liter extract) were 0.28 (±0.0084) kPa, 0.29 (±0.0362) kPa, and 4.90 (±0.1393) kPa, respectively. The values for black grass jelly with 10% b/v tapioca/liter extract were 0.73 (±0.0279) kPa, 0.85 (±0.0279) kPa, and 8.86 (±0.2785) kPa, respectively. The results of viscosity test, uniaxial compression test, and puncture test showed that leaves extract produces the firmest black grass jelly. Stems extract are produced the weakest jelly. Both stems and roots extracts produced sticky jelly. Firmer black grass jelly has a good ability to relax after the jelly is compressed instantaneously until certain strain value. This was shown by the relaxation test. The research concludes that black grass jelly from leaves extract has the best rheological characteristics compared to the jelly from other extracts. The rheological characteristics indicate that composites of other extracts (roots and stems) with leaves extract might be potential ingredients for black grass jelly.
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Judul: Improvement of Green Grass (Premna oblongifolia Merr.) Jelly’s Production Process and Its Effects on Physical and Functional Properties
Abstrak: Green grass jelly known to have functional efficacies of good health. Unfortunately, production process of green grass jelly is still relatively simple and it can be easily damaged if stored longer because it shall have syneresis and contaminated by high amounts of microbes. The objective of this study was to determine the effects of steaming and addition of NaHCO3 and hydrocolloid on physical, organoleptic and health functional properties of green grass jelly. Steaming can reduce the amount of microbial contamination on green grass jelly. However, steaming also has negative effects, i.e. decrease gel strength, increase level of syneresis, and changing the color of green to be brownish. The addition of NaHCO3 was expected to prevent the formation of brownish color. Hydrocolloid was also expected to reduce the level of syneresis and improve gel strength after steaming. Productions of green grass jelly in the conventional way use the ratio of green grass jelly leaves with water at 1:15. NaHCO3 concentration was determined based on the pH need to reduce the degradation of chlorophyll, i.e. pH of 7 and pH of 8. NaHCO3 concentrations used in the formulation were 0% (as control), 0.125% (to reach pH about 7), and 0.583% (to reach pH about 8). Based on the analysis of taste, NaHCO3 concentration of 0.125% was chosen because it is tasteless. Based on the analysis of color, NaHCO3 concentration of 0.125% has the most negative a value, meaning that the gel has greenest color. Based on the rate of syneresis, NaHCO3 concentration of 0.125% has the lowest rate of syneresis. In addition, the change in pH that occurred is not too volatile. NaHCO3 concentration used was 0.125%. The optimum gelling time was 2.5 hours since it has the highest viscosity value. Alginate could not be used because it does not form a gel when mixed with the green grass extract, with or without CaCO3. LMP and mixture of alginate and LMP could not be used because it could not form a gel when mixed with green grass extract without the use of CaCO3. The addition of CaCO3 resulted in lighter green color. Hydrocolloid that can be used is the mixture of kappa and iota carrageenan in the ratio of 1:1. By determination the variance of 0.25%, the concentrations of carrageenan which could form a good gel structure were 1.25% to 3.00%. Based on the analysis of texture, the carrageenan concentration which gave insignificantly different texture from commercial green grass jelly was 2.00%. Moreover, it has not too volatile pH changes. On the syneresis parameter, addition of 2.50% carrageenan was able to produce the lowest syneresis rate compared to other concentrations. Based on the analysis of color, carrageenan concentrations that produced insignificantly different color with the color of commercial green grass jelly was 2.00%. In addition, the concentration of 2.25% was also considered to be close to the color of green grass jelly commercial. It is also supported with a good rupture strength value of green grass jelly with the addition of 2.25% carrageenan. Sensory analysis showed the best carrageenan concentration was 2.00%. Steaming could
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Judul: Penyebaran virus Newcastle-Disease (ND) pada burung liar
Abstrak: Banyak usaha yang telah dilakukan untuk mencegah dan mengendalikan terjadinya serangan wabah ND, seperti misalnya peningkatan sanitasi dan vaksinasi ND. Akan tetapi sam pai saat ini pengendaliannya belum dapat dilakukan secara tuntas. Banyak masalah yang menyebabkan kegagalan dari usaha untuk mengendalikan wabah ND, salah satu masalah yang perlu dipertimbangkan dalam penanggulangan wabah ND adalah sumber dan penyebaran virus ND oleh burung liar (Ronohardjo, 1980). Walaupun telah diketahui bahwa burung liar mempunyai peranan dalam penyebaran penyakit unggas, tetapi harus diakui bahwa sedikit sekali informasi mengenai jenis burung yang mempunyai potensi sebagai sumber dan penyebar virus ND. Selain menyebarkan penyakit unggas, burung liar juga dapat menyebarkan penyakit mammalia (Ottis and Bachmann, 1983). ...
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