Judul: Kadar Total  Fenolik dan Aktivitas Antioksidan Ekstrak Buah Kapulaga Jawa (Amomum  compactum) dengan Perbedaan Metode dan Durasi Ekstraksi
Abstrak: Metode dan durasi ekstraksi akan memengaruhi kadar senyawa fenolik dan aktivitas antioksidan buah kapulaga jawa. Penelitian ini bertujuan mengukur dan membandingkan pengaruh metode dan durasi ekstraksi terhadap kandungan total fenolik dan aktivitas antioksidan dari ekstrak metanol buah kapulaga jawa asal Bogor. Buah kapulaga jawa diekstraksi dengan metode Continuous Shaking Extraction (CSE), Microwave Assisted Extraction (MAE), dan Ultrasonic Assisted Extraction (UAE) dengan perbedaan durasi ekstraksi. Kadar total fenolik diukur menggunakan metode Folin Ciocalteu dan aktivitas antioksidan diukur dengan metode ABTS dan CUPRAC. Kadar total fenolik metode ekstraksi MAE dengan durasi ekstraksi 3 menit (1,2633 mg EAG/g bobot kering) lebih tinggi dibandingkan dengan kadar total fenolik dari metode CSE dan UAE. Aktivitas antioksidan tertinggi metode ABTS (12,9332 µmol TE/g bobot kering) dan CUPRAC (38,1466 µmol TE/g bobot kering) didapatkan pada metode ekstraksi MAE durasi 3 menit. Kadar total fenolik setiap metode dan durasi ekstraksi menunjukkan korelasi yang positif terhadap aktivitas antioksidan., The effects of different extraction methods and durations on the levels of java cardamom fruit’s phenolic compounds and antioxidant activity were evaluated in this work. This research was aimed to measure and compare the effect of extraction method and duration on total phenolic content (TPC) and antioxidant activity in methanol extract of java cardamom fruit from Bogor. The sample was extracted by Continuous Shaking Extraction (CSE), Microwave Assisted Extraction (MAE), and Ultrasonic Assisted Extraction (UAE) with different duration. TPC was measured by the Folin Ciocalteu method and antioxidant activity was assayed using ABTS and CUPRAC methods. The TPC obtained from MAE for 3 minutes (1,2633 mg EAG/g dry weight) was the highest compared to those obtained from CSE and UAE methods. The highest antioxidant activity determined by ABTS (12,9332 µmol TE/g dry weight) and CUPRAC (38,1466 µmol TE/g dry weight) methods was obtained in MAE method with 3 minutes of extraction duration. The total phenolic content of each method and duration of extraction showed a positive correlation to the antioxidant activity.
Keyword: Antioxidant activity, Extraction method, Java cardamom, Phenolic

Judul: Analysis of Total Flavonoid Content and Antioxidant Activity  Java Cardamom Fruit with Different Extraction Methods and Durations
Abstrak: Penyebab kematian tertinggi di dunia termasuk Indonesia adalah penyakit degeneratif. Penyakit degeneratif disebabkan oleh radikal bebas yang masuk kedalam tubuh sehingga terjadi stress oksidatif. Buah kapulaga jawa (Amomum compactum) merupakan salah satu rempah yang mengandung metabolit sekunder sebagai sumber antioksidan. Perbedaan metode dan durasi ekstraksi pada buah kapulaga jawa dilakukan untuk mengetahui kadar total flavonoid dan aktivitas antioksidan terbaik. Metode ekstraksi yang digunakan yaitu CSE (Continuous Shaker Extraction), UAE (Ultrasonic Assisted Extraction), dan MAE (Microwave Assisted Extraction). Pengujian aktivitas antioksidan dengan metode DPPH dan FRAP. Metode dan durasi ekstraksi memiliki pengaruh terhadap total flavonoid dan aktivitas antioksidan. Kandungan tertinggi flavonoid didapatkan ekstrak metode CSE dengan durasi 360 menit (3,202 ± 0,337 mg QE g-1 bobot kering) dan aktivitas antioksidan tertinggi dari metode DPPH dan FRAP dihasilkan ekstrak dari metode MAE dengan durasi 3 menit (8,078 ± 0,960 dan 18,637± 4,631 μmol TE g -1 bobot kering). Kandungan total flavonoid dari ketiga metode ekstraksi dengan aktivitas antioksidan metode DPPH berkorelasi positif, kuat, dan signifikan. Kandungan total flavonoid dengan aktivitas antioksidan metode FRAP berkorelasi positif, sedang dan tidak signifikan pada metode CSE dan UAE, sedangkan pada metode MAE berkorelasi positif, kuat, dan signifikan., The highest cause of death globally, including in Indonesia, is caused by non-communicable disease or degenerative disease. Many degenerative disorders occur due to free radicals that enter the body and cause oxidative stress. Java cardamom fruit (Amomum compactum) is one of the spices that can be a source of antioxidants because of the secondary metabolites it produces. The test of java cardamom fruit with different methods and durations of extraction was to determine total flavonoid content and high antioxidant activity. The extraction methods used were Continuous Shaker Extraction (CSE), Ultrasonic Assisted Extraction (UAE), and Microwave Assisted Extraction (MAE). Antioxidant activity was measured by DPPH and FRAP methods. The method and duration of extraction affect the total flavonoid content and antioxidant activity. The highest flavonoid content was found in the extract from the CSE method with a duration which was 360 minutes (3,202 ± 0,337 mg QE g-1 dry weight) and the highest antioxidant activity of the DPPH and FRAP methods was found in the extract from MAE method with a duration which was 3 minutes (8,078 ± 0,960 and 18,637± 4,631 μmol TE g-1 8,078 ± 0,960 and 18,637± 4,631 μmol TE g-1 dry weight). The flavonoid content of the three extraction methods (CSE, MAE, and UAE) with the antioxidant activity of the DPPH method has a positive, strong, and significant correlation. The flavonoid content with the antioxidant activity of the FRAP method was positively, moderately, and significantly correlate with CSE and UAE methods, while the MAE method had a positive, strong, and significant correlation.
Keyword: antioxidant, extraction method, java cardamom fruit, total flavonoid

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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