Judul: Microbiological Properties and Antioxidant Activity of Eri Silkworm Pupae (Samia cynthia ricini) Flour with Different Particle Size
Abstrak: Pupa ulat sutra Eri (Samia cynthia ricini) memiliki nilai gizi dan sifat antioksidan yang dapat dijadikan sebagai produk pangan berupa tepung. Sebagai produk pangan, diperlukan uji analisis mikrobiologi sehingga diketahui kelayakannya. Sifat Mikrobiologi dianalisis dengan menghitung Angka Lempeng Total, E. coli, S. aureus dan Salmonella sp. Sementara itu, adanya proses pengayakan tepung dengan tujuan menghomogenkan ukuran partikel dapat memengaruhi aktivitas antioksidan. Maka dari itu, nilai aktivitas antioksidan pada tepung sutra Eri dengan ukuran partikel 80 mesh dan 60 mesh diuji melalui aktivitas penghambatan DPPH (2.2-Diphenyl-1-picrylhydrazyl) dan kapasitas antioksidan. Analisis data menggunakan rancangan acak lengkap (RAL) dan uji T-Independen. Hasil menunjukkan bahwa nilai ALT, E. coli dan Salmonella sp. telah memenuhi ketentuan standar SNI 3751:2009. Jumlah sel S. aureus pada tepung ialah <105 koloni/g, sehingga mengindikasikan bahwa jumlah cemaran tidak melebihi ambang batas. Selain itu, analisis aktivitas antioksidan kedua tepung tergolong kuat meskipun ukuran partikel tepung pupa sutra Eri yang berbeda tidak memberikan pengaruh nyata., Eri silkworm pupae (Samia cynthia ricini) have nutritional and antioxidant values that can be used as food products in the form of flour. As a food product, it is necessary to test its microbiological properties so that its feasibility is known. Microbiological properties were analyzed by calculating the Total Plate Count, E. coli, S. aureus and Salmonella sp. Meanwhile, the process of sifting flour with the aim of homogenizing the particle size will affect the antioxidant activity. Therefore, the antioxidant activity in Eri silk flour with particle sizes of 80 mesh and 60 mesh was tested through DPPH inhibition activity and antioxidant capacity. Data analysis used a completely randomized design (CRD) and independent T-test. The results showed that the value of the TPC, E. coli and Salmonella sp. has met the standard provisions of SNI 3751:2009. The number of S. aureus cells was <105 colonies/g which indicated that the amount of contamination did not exceed the thresholdhe analysis of the antioxidant activity was classified as strong although the different particle size did not have a significant effect.
Keyword: antioxidant, flour, microbiological properties, pupae, Samia cynthia ricini

Judul: Antioxidant, Organoleptic, and Microbiological Activities of Eri Silkworm (Samia cynthia ricini) Pupae Flakes Product
Abstrak: Ulat sutra Eri (Samia cynthia ricini) merupakan ternak yang menghasilkan produk sampingan berupa pupa. Pupa dapat dimanfaatkan sebagai bahan substitusi tepung polenta pada pembuatan produk pupae flakes. Penelitian ini bertujuan untuk menganalisis cemaran mikrobiologi (total plate count, Escherichia coli, dan Staphylococcus aureus), aktivitas dan kapasitas antioksidan, serta organoleptik pada produk flakes ulat sutera eri. Penelitian ini menggunakan rancangan acak lengkap (RAL) dengan tepung polenta dengan tepung pupa pada tiga taraf berbeda yaitu 0%, 4%, dan 8%. Hasil analisis mikrobiologi pada pengujian total plate count dan bakteri Escherichia coli memenuhi standar SNI, namun pengujian bakteri Staphylococcus aureus tidak memenuhi standar SNI. Pengujian antioksidan pupae flakes menunjukkan peningkatan aktivitas dan kapasitas antioksidan. Hasil pengujian organoleptik pupae flakes memberikan pengaruh nyata terhadap semua atribut pada uji hedonik dan mutu hedonik., Eri silkworm (Samia cynthia ricini) is a livestock that produces by-product of pupae. Pupae can be used as a substitute for polenta flour to manufacture pupa flakes. This study aims to analyze microbiological contaminants (total plate count, Escherichia coli, and Staphylococcus aureus), antioxidant activity and capacity, and organoleptic in silkworm flakes products. This study used a completely randomized design (CRD) with polenta flour and pupa flour at three levels, namely 0%, 4%, and 8%. The results of microbiological analysis on total plate count testing and Escherichia coli bacteria met the SNI standards, but the Staphylococcus aureus bacteria test did not meet the SNI standards. Antioxidant testing of pupae flakes showed an increase in antioxidant activity and capacity. The organoleptic testing results of pupae flakes significantly affected all attributes in the hedonic test and hedonic quality.
Keyword: antioxidant, eri silkworm, microbiology, organoleptic, pupae flakes

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.
Keyword: