Judul: Metode pengeringan Andaliman (Zanthoxylum acanthopodium DC.) untuk memperoleh mutu sensori aroma dan sensasi trigeminal yang optimum
Abstrak: Andaliman merupakan salah satu rempah tradisional dari Sumatera Utara yang memiliki aroma dan sensasi trigeminal yang khas. Kadar air yang tinggi pada andaliman menyebabkan rempah ini menjadi sulit untuk disimpan dalam waktu lama. Enam metode pengeringan digunakan dalam penelitian ini, yaitu pengeringan dengan sinar matahari, angin, oven, far infra red dryer tipe oven, fluidized bed dryer, dan freeze dryer. Metode pengeringan dengan oven, berdasarkan mutu kimia, fisik, sensori, serta pertimbangan ekonomi, dari keenam metode pengeringan tersebut dipilih untuk dioptimumkan. Optimasi dilakukan dengan menggunakan RSM (response surface methodology) dengan faktor suhu dan waktu pengeringan berdasarkan respon kadar air, aktivitas air, mutu sensori aroma dan sensasi trigeminal. Hasil pengolahan data dengan bantuan perangkat lunak Design Expert 7 menghasilkan kondisi yang terpilih untuk andaliman kering dengan aroma dan sensasi trigeminal optimum adalah pengeringan dengan suhu 54 °C dan waktu selama 480 menit dengan tingkat desirability 0.674. Respon aktivitas air, kadar air, dan sensasi trigeminal dipengaruhi oleh suhu dan waktu pengeringan. Respon aroma kurang dipengaruhi suhu dan waktu pengeringan tetapi masih dapat digunakan dalam membantu model optimasi pengeringan andaliman. Andaliman kering dapat diterapkan pada sambal, terutama untuk parameter aroma maupun sensasi trigeminal, andaliman kering menunjukkan penilaian yang lebih baik daripada andaliman segar, kecuali untuk metode kering angin., Andaliman is one of the traditional spices from North Sumatra which has distinctive aroma and trigeminal sensation on the tongue. High moisture content on andaliman causes this spice difficult to be stored for a long time. Six drying methods used in this study, namely sun, air ,oven,oven type far infra red dryer, fluidized bed dryer, and freeze dryer. Oven drying method, based on the quality of the chemical, physical, sensory, and economic considerations, of the six drying methods is selected to be optimized. Selection also considers the cost and time required. Optimization will be done using the RSM (response surface methodology) with two factors, i.e. temperature and drying time and based on the responses of water content, water activity, intensity of aroma and trigeminal sensation. The results of data processing with the aid of Design Expert 7 software produces a chosen condition for dried andaliman with optimum aroma and trigeminal sensation, that is drying with temperature of 54 °C for 480 minutes with 0.674 level of desirability. Water activity, moisture content, and trigeminal sensation responses are influenced by temperature and drying time. Aroma response is less influenced by drying temperature and time but still can be used to help the andaliman drying optimization model . Dry andaliman can be applied to the sauce, especially for aroma and trigeminal sensation, dry andaliman showed better score than fresh andaliman, except for the air drying method.
Keyword: andaliman, metode pengeringan, suhu, optimasi, RSM

Judul: Perubahan Senyawa Volatil dan Mati Rasa Andaliman (Zanthoxylum acanthopodium) oleh Berbagai Teknik Pengeringan
Abstrak: Andaliman (Zanthoxylum acanthopodium DC) is an endemic plant from North Sumatera, commonly used as spices and folk medicines. Andaliman has a robust citrus aroma and numbing trigeminal sensations. Unfortunately, the research, usage, and popularity of andaliman are much behind its related species, such as Z. piperitum (Japanese pepper) and Z. bungeanum (Sichuan pepper). The main hurdles in fresh andaliman usage are the fast rotting and rapid flavor degradation. Proper processing techniques by farmers and industries will be crucial to expand its usage. Drying could prevent andaliman from degradation by reducing the moisture content; however, its effects on volatiles, numbing compound, and aroma profile have not been fully understood. Unsaturated alkylamides (sanshools) have been reported to be responsible for the unique numbing sensation. Analysis of sanshools is usually conducted using column chromatography or High Pressure Liquid Chromatography; however, these methods tend to be time-consuming and requires a large amount of costly solvent. On the other hand, aroma analysis is conducted using Gas Chromatography-Mass Spectrometry (GC-MS), which requires researchers to use two types of analytical methods to get the complete picture of both the aroma and taste of andaliman. However, three studies managed to analyze sanshools by GC-MS, which will shorten the research timeline and reduce research costs. This research was composed of three main stages: drying of andaliman (sun, sunshade, shade, oven, and freeze drying), confirmation of the GC-MS parameter, analysis of the volatiles, sanshools, sensory and physical characteristics. The volatiles and sanshool analysis were conducted with GC-MS, while the sensory analysis used the Rate All That Apply-Hedonic method. Physical characteristics such as moisture, water activity, yield, bulk density, and color were analyzed. Statistical data analysis using Principal Component Analysis (PCA), one-way ANOVA, Duncan posthoc, Pearson’s correlation, and Partial Least Square regression analysis were conducted to evaluate the impact of drying on volatiles, numbing, and sensory profile as well as to determine the volatiles responsible for andaliman aroma quality. The logarithmic thin-layer drying model best-described andaliman drying kinetics. The drying process significantly altered andaliman appearance, aroma profile and physical properties. No significant difference was found in the yield of each drying method; however, shade drying resulted in the highest moisture and water activity, while sun drying and freeze drying resulted in the lowest moisture content and water activity. Freeze drying resulted in the lowest bulk density. All drying methods managed to produce andaliman with less than 17.90% moisture content and 0.6 water activity, indicating the drying targets have been achieved. Generally, drying increased the a*, indicating green color degradation, however, no significant difference was observed in the a* values of dried samples. GC-MS analysis of all chloroform andaliman extract managed to detect total of 67 peaks while identifying 42 compounds. However, 25 unidentified peaks could comprise of other sanshool isomers. Fresh and dried andaliman generally had similar total relative content of volatiles and chromatogram pattern, differing mostly in the individual compound quantities. The content of limonene, (E)-2-hexenal, geranial, α-pinene, sabinene, and β-myrcene as well as the intensities of citrus and green aroma tended to decrease. In contrast, the content of geranyl acetate, citronellal,
Keyword: Zanthoxylum, andaliman, drying, aroma, sanshool

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model