Judul: Substitution of Purple Sweet Potato (Ipomoea batatas L.) Flour as Fiber and Antioxidant Source in Flaky Crackers for Adolescents.
Abstrak: Obesitas pada remaja di Indonesia, khususnya remaja pada usia 16-18 tahun, mengalami peningkatan secara nasional dengan prevalensi 7.3%. Konsumsi makanan selingan dengan kandungan serat dan antioksidan yang cukup dapat menjadi salah satu upaya dalam mengatasi obesitas. Flaky crackers merupakan salah satu jenis makanan selingan yang biasa di konsumsi di Indonesia. Penelitian ini bertujuan untuk mengkaji pemanfaatan tepung ubi jalar ungu pada flaky crackers tinggi serat dan antioksidan untuk remaja. Penelitian dilakukan pada bulan November-Desember 2020 dan Maret-April 2021. Taraf penggunaan tepung ubi jalar ungu meliputi F1(10%), F2(20%), F3(30%), dan F4(40%). Hasil penelitian menunjukkan flaky crackers dengan substitusi tepung ubi jalar ungu tertinggi (F4) merupakan formula terpilih dengan daya terima dan kandungan gizi paling baik. Flaky crackers F4 memiliki klaim tinggi serat dengan kandungan serat sebesar 10,8 g per 100 g produk. Kandungan energi flaky crackers F4 per takaran saji memenuhi 10% kebutuhan energi remaja usia 16-18 tahun., Obesity in Indonesia, especially experienced by adolescents aged 16-18 years has increased nationally with a prevalence of 7.3%. Consumption of snacks with sufficient fiber and antioxidant content can be an effort to overcome obesity. Flaky crackers are one of the most common snacks consumed in Indonesia. This study aims to examine the effect of purple sweet potato flour substitution on high fiber and antioxidant flaky crackers for adolescents. The research was conducted in November-December 2020 and March-April 2021. The level of purple sweet potato flour were F1(10%), F2(20%), F3(30%), and F4(40%). The results showed that flaky crackers with the highest purple sweet potato flour substitution (F4) were the chosen formula with the best acceptability and nutritional content. F4 flaky crackers were claimed to be high in fiber with a fiber content of 10.8 g in 100 g of product. The energy content of F4 flaky crackers per serving size meets 10% of the energy needs of adolescents aged 16-18 years.
Keyword: antioksidan, flaky crackers, serat, tepung ubi jalar ungu

Judul: Indeks Glikemik Flakes Berbahan Dasar Ubi Jalar Ungu (Ipomoea batatas L.) dan Kacang Merah (Phaseolus vulgaris L.).
Abstrak: Flakes merupakan salah satu produk alternatif untuk sarapan karena mudah dan cepat untuk disajikan. Produk flakes yang banyak beredar dipasaran berbahan dasar jagung dan gandum, sedangkan flakes berbahan dasar umbiumbian belum banyak dikembangkan. Penelitian ini bertujuan untuk menganalisis pengaruh konsumsi flakes (F1) ubi jalar ungu (100:0) dan flakes (F2) ubi jalar ungu dan kacang merah (70:30) terhadap respons glukosa darah. Hasil analisis kandungan pati F1 49.44% dan F2 47.76%. Kandungan amilosa terhadap pati F1 34.25% dan F2 29.13%. Kandungan amilopektin terhadap pati F1 15.15% dan F2 18.63%. Nilai indeks glikemik flakes F1 sebesar 76.34 dan flakes F2 sebesar 73.12. Nilai IG kedua flakes termasuk dalam kategori tinggi. Uji statistik independent sample t-test menunjukkan tidak terdapat perbedaan yang signifikan antara flakes F1 dan F2 terhadap nilai indeks glikemik. Produk flakes dengan indeks glikemik tinggi dapat meningkatkan respons glukosa darah, sehingga dapat dikonsumsi saat tubuh membutuhkan glukosa darah yang cepat.
Keyword: amilopektin, amilosa, pati, serat pangan, tinggi indeks glikemik

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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