Judul: Kapasitas Antioksidan Bir Pletok pada Berbagai Rasio Kayu Manis, Secang, dan Sukrosa
Abstrak: Bir pletok merupakan minuman tradisional khas Betawi yang berpotensi menjadi salah satu minuman mengandung antioksidan, karena komposisinya yang terdiri atas banyak rempah-rempah. Bahan baku pembuatan bir pletok telah banyak dikaji terkait potensi antioksidannya. Pada proses pembuatan bir pletok, diketahui terdapat perbedaan teknik perebusan dan rasio rempah yang dapat bepengaruh terhadap kapasitas antioksidan bir pletok. Penelitian ini bertujuan membandingkan pengaruh perbedaan dua teknik perebusan, tiga rasio kayu manis dan secang, serta pengaruh penambahan gula pasir (sukrosa) terhadap kapasitas antioksidan bir pletok. Pada penelitian ini, bir pletok yang semua bahannya direbus selama lima belas menit dengan rasio secang 15 gram dan kayu manis 2 gram memiliki karakterisasi kimia yang lebih baik dibandingkan perlakuan lainnya. Bir pletok tersebut memiliki kapasitas antioksidan sebesar 0,40 mg AEAC/g bahan, total fenolik 3,19 mg GAE/g bahan, dan total flavonoid senilai 0,23 mg QE/g bahan. Secang memiliki kandungan fenolik dan flavonoid yang lebih tinggi dibandingkan kayu manis. Oleh karena itu, semakin besar rasio secang terhadap kayu manis, kapasitas antioksidan bir pletok juga semakin tinggi. Sukrosa yang ditambahkan dalam bir pletok menurunkan kapasitas antioksidannya. Penambahan 20% sukrosa menghasilkan kapasitas antioksidan yang lebih rendah yakni 0,37 mg AEAC/g bahan, dibandingkan bir pletok tanpa penambahan sukrosa yakni 0,40 mg AEAC/g. Hasil uji korelasi Pearson yang dilakukan, menunjukkan adanya korelasi yang kuat untuk setiap hasil pengukuran kapasitas antioksidan pada semua metode uji yang dilakukan. Semakin rendah kapasitas antioksidan metode DPPH dan FRAP, maka total fenolik dan flavonoid bir pletok semakin rendah.
Keyword: antioxidant, bir pletok, cinnamon, sappan wood, sucrose

Judul: Pengaruh Suhu dan Transparansi Kemasan terhadap Stabilitas Kapasitas Antioksidan sebagai Parameter Umur Simpan Bir Pletok
Abstrak: Bir Pletok is a Betawi traditional beverage product made from spices and herbs. Bir Pletok has many advantages, such as to keep body warm and to prevent cold . Bir pletok’s key benefit is related to its antioxidant capacity. The packaging and the storage environment are two important factors in the beverage industry include bir pletok. These factors could affect the antioxidant capacity. The antioxidant capacity in food could decrease due to high temperature and other specific conditions. In the present study the change of antioxidant capacity during the storage and the storage time of bir pletok in the bottle glass packaging with different transperancy and different storage temperature were evaluated. ASS method was used to find the storage time of bir pletok with temperature parameter and ESS method was used to find the storage time of bir pletok with packaging transperancy parameter , whereas the reduction of DPPH method was used to determine the antioxidant capacity of bir pletok during 8 weeks of storage. The storage time of bir pletok that had been storage in 300, 370C, and 500C were 29,45 days, 22,55 days, and 10,67 days respectively. Among the three levels of storage temperatures evaluated in this research, the best temperature for bir pletok storage is 300C. The storage time of bir pletok that had been storage in transparent, brown, and dark bottle glass were 19,28 days, 25,05 days, and 29,91 days respectively. The result of the study showed that the non-transparent packaging was the best condition for bir pletok storage.
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Judul: The Solution of Nonlinear Volterra Integral Equation using Linearization Method.
Abstrak: Many natural phenomena can be explained by mathematical models. One of those models is in the form of Volterra integral equation, which is usually nonlinear. Analitically, a nonlinear form is difficult to solve. Therefore, this research is aimed to discuss solution of Volterra integral equation using linearization method. Linearization is done to nonlinear integrand with Taylor series expansion. According to this linearization, a numerical solution of Volterra integral equation is obtained using MATLAB 7.0.1 software. Validity of this method is tested by comparing the approximate with the exact solution. The result of this research shows that the numerical solution agree with the exact solution quite well.
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