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: Physicochemical Characteristics of Eri  Silkworm Pupae Flour (Samia cynthia ricini) with Different Particle Sizes.
Abstrak: Pupa adalah hasil samping di pengolahan serat sutra. Penggunaan pupa yang kurang optimal dapat menyebabkan pencemaran lingkungan. Sebagai produk pangan, diperlukan uji analisis sifat fisikokimia sehingga diketahui nilai gizinya. Sifat fisikokimia dianalisis dengan uji pH, uji aw, warna, dan analisis proksimat. Adanya pengayakan tepung pupa dilakukan dengan tujuan menghomogenkan ukuran partikel. Analisis data yang digunakan adalah Uji T-Independen. Hasil menunjukkan bahwa pH, aw, kadar air, kadar lemak, protein ukuran partikel 80 mesh tepung pupa lebih baik dari ukuran partikel 60 mesh. Akan tetapi, kadar abu, serat kasar, dan karbohidrat pada tepung 60 mesh lebih baik dari ukuran partikel 80 mesh. Ukuran partikel tidak memengaruhi karakteristik fisikokimia tepung pupa., Pupa is a byproduct in the processing of silk fiber. Suboptimal use of pupa can lead to environmental pollution. As a food product, it is necessary to conduct a physical-chemical analysis to determine its nutritional value. Physical-chemical properties are analyzed through pH testing, water activity (aw) testing, color analysis, and proximate analysis. Sieving of pupa flour is carried out with the aim of homogenizing particle size. The data analysis used is the Independent T-Test. The results show that pH, aw, moisture content, fat content, and protein content of 80 mesh pupa flour are better than that of 60 mesh particle size. However, ash content, crude fiber, and carbohydrates in 60 mesh flour are better than that of 80 mesh particle size. Particle size does not affect the physical-chemical characteristics of pupa flour.
Keyword: Fisikokimia, Proksimat, Pupa, Samia cynthia ricini, Tepung Pupa

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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