Judul: Variasi Morfologi Dan Pemanfaatan Andaliman (Zanthoxylum Acanthopodium) Di Sumatera Utara
Abstrak: Andaliman (Zanthoxylum acanthopodium DC.) termasuk ke dalam suku Rutaceae merupakan salah satu jenis bumbu masakan khas Asia yang belum banyak dikenal. Bumbu ini di Indonesia hanya dikenal dalam masakan Batak sebagai “merica batak”. Di Indonesia, andaliman dapat tumbuh subur di pegunungan di sekitar danau Toba yang terletak di Sumatera Utara, pada daerah berketinggian sekita 1300 m dpl dengan temperatur 15-18 0C. Penelitian ini dilakukan untuk mengeksplorasi dan menganalisis keberagaman andaliman di Sumatera Utara berdasarkan ciri morfologi. Sampel spesimen diambil dari 27 tanaman andaliman yang dikumpulkan dari Kabupaten Simalungun, Dairi, Tapanuli Utara, dan Toba Samosir, Sumatera Utara, pada bulan Februari 2014 untuk Februari 2015. Pengamatan morfologi dan pengidentifikasian spesimen dilaksanakan di Herbarium Bogoriense (BO) Pusat Penelitan Biologi LIPI, Cibinong, dan di Laboratorium Biologi Tumbuhan, Pusat Penelitian Sumber Daya Hayati dan Bioteknologi (PPSHB) IPB, Dramaga, Bogor. Semua ciri morfologi yang terdiri atas 24 ciri meliputi ciri kualitatif dan kuantitatif diamati dan disajikan dalam bentuk skor dalam matriks data. Hasil skor ciri morfologi membentuk matriks data yang dianalisis dan dikelompokan berdasarkan tingkat kemiripan dalam SIMQUAL (Similarity for Qualitative Data) dengan menggunakan koefisien SM (Simple Matching). Pengelompokan dianalisis dengan menggunakan SAHN (Sequential Agglomerative Hierarchical and Nested Clustering) dengan metode UPGMA (Unweighted Pair Group Method with Arithmatic Average). Metode tersebut tersaji dalam program software NTSYS (Numerical Taxonomy and Multivariate System) versi 2.11a. Penyeleksian ciri morfologi dilakukan berdasarkan syarat keberbedaan (distinctness), keseragaman (uniformity), kestabilan (stability), serta mudah, dan praktis dengan menggunakan 24 ciri morfologi dari andaliman dikelompokkan menggunakan metode UPGMA dari matriks data yang diputar. Berdasarkan 24 ciri morfologi yang meliputi batang, daun, bunga, dan buah dari 27 tanaman andaliman di Sumatera Utara yang dikelompokkan menjadi 4 kelompok. Namun, hanya 10 ciri yang digunakankan untuk memisahkan tanaman andaliman menjadi 4 kelompok. Karakteristik kultivar andaliman „Simanuk‟ mengacu pada kelompok I, „Sihorbo‟ mengacu pada kelompok II, „Silokot‟ mengacu pada kelompok III, sedangkan kelompok IV mengacu ciri dari kultivar andaliman „Sikoreng‟. Andaliman kelompok I, II, dan III dimanfaatkan sebagai “sambal Batak” dan “sambal tuk-tuk” karena warna buah muda hijau, di sisi lain, andaliman dalam kelompok IV dengan warna buah merah banyak digunakan sebagai bumbu masakan khas Batak, seperti “arsik ikan mas”, “sangsang”, dan “natinombur”.
Keyword: bumbu masakan khas Batak, Sihorbo, Simanuk, Silokot, Sikoreng

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: 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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