Judul: Kajian efisiensi energi proses penyulingan dan sifat fisik hasil penyulingan minyak serai dapur menggunakan tungku sekam dan heating mantel
Abstrak: Telah dilakukan penyulingan minyak atsiri dari bahan serai dapur menggunakan dua pemanas yaitu tungku sekam dan heating mantel. Pada perbandingan bahan (serai dapur : air = 0,125 Kg : 0,5 liter) penyulingan dengan pemanas tungku sekam membutuhkan energi 6022,5 Kkal, lama penyulingan 3660 sekon, biaya Rp 912,5 dengan rata-rata rendemen minyak yang dihasilkan 0,0635 %. Penyulingan dengan jumlah bahan sama menggunakan heating mantel membutuhkan energi 832,143 Kkal, lama penyulingan 6990 sekon, biaya Rp 608,6 dan menghasilkan rendemen 0,114 %. Debit destilat dipengaruhi oleh kalor yang dihasilkan oleh tungku sekam dan heating mantel. Kualitas minyak serai dapur yang dihasilkan dengan pemanas tungku sekam lebih baik dibandingkan heating mantel dilihat dari segi warna minyak serai dan indeks bias minyak. Minyak serai yang dihasilkan dengan pemanas tungku sekam berwarna coklat muda dan nilai indeks biasnya berada pada rentang nilai 1,4830-1,4890.
Keyword: Water distillation, Cymbapogon spp., Gramiae, Lemon grass oil

Judul: Study of Citronella Oil Distillation Using Water-Steam  Distillation Method with Variation of Material Chopping Size
Abstrak: Indonesia merupakan salah satu negara penghasil minyak atsiri terbesar di Dunia. Minyak serai wangi menjadi salah satu komoditi ekspor potensial Indonesia. Penelitian ini bertujuan mengkaji pengaruh ukuran perajangan serai wangi terhadap rendemen dan mutu minyak serai wangi yang dihasilkan dan mengkaji kinerja alat penyulingan dengan metode air dan uap. Bahan yang digunakan adalah serai wangi varietas Mahapengiri yang diperoleh dari petani di Bogor. Serai wangi dibersihkan, dirajang dengan ukuran yang berbeda (5 cm dan 10 cm), lalu dikering-anginkan. Sebanyak 3 kg rajangan serai wangi dimasukkan ke dalam ketel penyulingan dan ditambahkan air sebanyak 18 liter. Penyulingan dilakukan selama 4 jam sejak destilat keluar dari kondensor. Hasil penelitian menunjukkan bahwa perajangan bahan tidak berpengaruh nyata terhadap rendemen, densitas, indeks bias dan warna minyak serai wangi. Pada ukuran perajangan 5 cm diperoleh rendemen, densitas dan indeks bias berturut-turut sebesar 0,26%, 0,809 g/cm3 dan 1,474 dengan warna kuning pucat. Pada ukuran perajangan 10 cm rendemen, densitas dan indeks bias berturut-turut sebesar 0,15 %, 0,842 g/cm3 dan 1,471 dengan warna kuning pucat hingga kuning kecoklatan. Kinerja alat distilasi menghasilkan efisiensi penguapan air, efisiensi ketel penyulingan, dan efisiensi kondensor berturut-turut sebesar 20,56%, 70,76%, dan 67,98% dengan efisiensi total proses penyulingan sebesar 9,83%.
Keyword: citronella oil, distillation, efficiency, quality, yield

Judul: Quantitative Trait Loci Mapping for Trait in Categorical Scale
Abstrak: Genes or regions on chromosome underlying a quantitative trait are called Quantitative Trait Loci (QTL). Characterizing genes controlling quantitative trait on their position in chromosome and their effect on trait is through a process called QTL mapping. In estimating the QTL position and its effect, QTL mapping basically utilize the association between QTL and DNA markers. However, many important traits are obtained in categorical scale, such as resistance from certain disease. From a theoretical point of view, QTL mapping method assuming continuous trait could not be applied to categorical trait. This research was focusing on the assessment of the performance of Maximum Likelihood (ML) and Regression (REG) approach employed in QTL mapping as well as the performance of Lander and Botstein (LB) and Piepho method in determining critical value in testing the existence of QTL for binary and ordinal trait by means of simulation study. The simulation study to evaluate the performance of ML and REG approach was conducted by taking into account several factors that may affecting the performance of both approaches. The factors are: (1) marker density; (2) QTL effect; (3) sample size; (4) shape of phenotypic distribution; (5) number of categories; and (6) number of QTL. Moreover, the simulation study for evaluating LB and Piepho method in determining critical value was conducted by generating distribution of the test statistic under null hypothesis. From simulation study, it was obtained that LB and Piepho method showing similar performance in determining critical value in testing the existence of QTL for binary and ordinal trait. The simulation study also indicating that both methods could be used in determining critical value in QTL mapping analysis for binary trait as well as for ordinal trait if the REG approach is used but not if ML approach is used due to their poor performance. In assessing the performance of ML and REG approach in QTL mapping analysis for binary trait, the two approaches showing comparable performance; whereas for ordinal trait REG approach showing poor performance compared with ML approach in estimating thresholds. As a result, in QTL mapping analysis, ML and REG approach could be used when dealing with binary trait, whereas ML approach is suggested when dealing with ordinal trait.
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