Judul: Protein dan Peptida Susu Kambing serta Potensinya sebagai Antibakteri
Abstrak: Bioactive peptides are specific protein fragments derived from hydrolysis that has positive effect on human health. Caprine milk is one of animal protein sources with high nutrition and relatively easy to digest. Caprine milk has high protein content (3.4%) which is potential to produce bioactive peptides. Protease is an enzyme capable to hydrolyze protein, and thus is used to hydrolyze protein to produce bioactive peptide. Fragments of protein and peptide hydrolysates can be determined by SDS PAGE analysis that show protein profiles in the form of protein molecular weight. In this study, papain was used to produce bioactive peptides from caprine milk. The objective of this study was to analyze the profile of peptides from caprine casein hydrolyzed with papain, and analyze their bioactivity as antibacteria toward food pathogens bacteria Escherichia coli and Staphylococcus aureus. The caprine casein was produced by adding HCl to defatted caprine milk until isoelectric point and coagulated by centrifugation. Hydrolysis process was performed by incubating casein and whey with papain in optimum condition (pH 7, 50°C) for 15, 30, and 45 min. Hydrolysis was terminated by heating at 80°C, 15 minutes and then stored at -20°C. Culture of pathogenic bacteria that used in this study was Escherichia coli ATCC 25 922 and Staphylococcus aureus ATCC 25923. Protein and peptides samples that have been sterilized with membrane filter (0.45 μm) were analyzed the protein profile by SDS-PAGE (consisted of 15% running gel for casein samples, 20% running gel for whey samples, 4% stacking gel and subjected to electrophoresis at constant voltage and current of 70 volt and 50 mA) and the antibacterial activity by disc diffusion method and contact method. Caprine milk has ten protein bands with molecular weight of 68, 60, 55, 34, 24, 21, 19, 18, 15 and 11 kDa. After separation, all protein bands were maintained in casein with addition of 12 kDa protein bands, whereas whey has six protein bands with molecular weight of 85, 69, 61, 25, 14, and 12 kDa. Caprine casein hydrolysis by papain enzyme, hydrolyzed α-casein (MW 32 kDa), β-casein (MW 24 kDa) and other caprine milk protein after 15 minutes incubation leaving κ-casein (MW 21 kDa) and one new peptide band (MW 10 kDa). Papain hydrolyzed lactoferrin protein in whey that can be a factor which reduce the antibacterial activity in whey. Both casein, whey and their peptide hydrolysates inhibited E. coli but not S. aureus. Further analysis showed that casein (unhydrolyzed) reduced E. coli growth significantly by 2.8 log after 2 hours exposure and the inhibition increased by exposure time.
Keyword: antibacterial, bioactive peptides, caprine milk, papain, SDS-PAGE

Judul: Antioxidant Activity of Bioactive Peptides Produced by Goat Milk Protein Hydrolysis Using Papain Protease Enzyme
Abstrak: Fresh goat's milk has the main nutritional content of protein which is composed of peptides with biological abilities whose activation occurs after the hydrolysis process. This study aims to test the hydrolyzate of goat's milk, especially the Etawa breed (PE), which is hydrolyzed with papain enzymes to produce bioactive peptides with antioxidant activity along with protein profiles before and after hydrolysis. Goat milk was hydrolyzed at 37°C and 55°C for 1, 4, and 24 hours, followed by analysis of protein content with the Bradford method, antioxidant activity with the DPPH and P-FRAP methods, and measurement of molecular weight with the SDS-PAGE method. Papain activity was obtained at 1.23 × 103 U/mL with a specific enzyme activity value of 1.86 × 103 U/mg. The protein content of goat's milk was 7.95 ± 0.01 mg/mL, but after being hydrolyzed at 55°C for 24 hours, the lowest value was 1.21 ± 0.02 mg/mL. The highest antioxidant activity of goat's milk peptides occurred at hydrolyzate at 55°C for 24 hours, increasing 94% by 62.86 ± 1.17 % RSA against DPPH and 11.96% by 131.72 ± 1.04 mgAAE/mL in P-FRAP compared to non-hydrolyzed. The molecular weight of goat's milk is 8-84 kDa, the hydrolyzate is found to be 7-24 kDA in size which is suspected to be β-casein (24 kDa) and αs2-casein (<10 kDa) as easily digestible proteins. Statistical data analysis showed that the antioxidant activity of goat's milk bioactive peptides was significantly different (P>0.05) on temperature and hydrolysis time by papain enzyme., Susu kambing segar memiliki kandungan gizi utama protein yang tersusun atas peptida dengan kemampuan biologis yang aktivasinya terjadi setelah proses hidrolisis. Penelitian ini bertujuan menguji hidrolisat susu kambing khususnya Peranakan Etawa (PE) yang dihidrolisis dengan enzim papain untuk menghasilkan peptida bioaktif dengan aktivitas antioksidan beserta profil protein sebelum dan setelah hidrolisis. Susu kambing dihidrolisis dengan suhu 37°C dan 55°C selama 1, 4, dan 24 jam, dilanjutkan analisa kadar protein dengan metode Bradford, aktivitas antioksidan dengan metode DPPH dan P-FRAP, dan pengukuran berat molekul dengan metode SDS-PAGE. Aktivitas papain diperoleh sebesar 1,23×103 U/mL dengan nilai aktivitas spesifik enzimnya sebesar 1,86×103 U/mg. Kadar protein susu kambing diperoleh sebesar 7,95±0,01 mg/mL, namun setelah dihidrolisis suhu 55°C selama 24 jam mendapatkan nilai terendah sebesar 1,21±0,02 mg/mL. Aktivitas antioksidan peptida susu kambing tertinggi terjadi pada hidrolisat suhu 55°C selama 24 jam, meningkat 94% sebesar 62,86±1,17 %RSA terhadap DPPH dan 11,96% sebesar 131,72±1,04 mgAAE/mL pada P-FRAP dibandingkan non-hidrolisis. Berat molekul susu kambing sebesar 8-84 kDa, didapatkan hidrolisatnya berukuran 7-24 kDa yang diduga β-kasein (24 kDa) dan αs2-kasein (<10 kDa) sebagai protein mudah cerna. Nilai analisis data statistik menunjukan aktivitas antioksidan peptida bioaktif susu kambing berbeda nyata secara signifikan (P>0,05) terhadap suhu dan waktu hidrolisis oleh enzim papain.
Keyword: SDS-PAGE, papain enzymes, goat milk, bioactive peptides, antioxidant

Judul: Gerak intertropical convergence zone di wilayah Indonesia
Abstrak: Intertropical Convergence Zone (ITCZ) merupakan salalı satu faktor yang mempengaruhi intensitas dan distribusi curah hujan di Indonesia. Pada umumnya daerah yang dilalui ITCZ memiliki curah hujan yang tinggi. Oleh sebab itu perlu diketahui posisi ITCZ setiap bulan. Dalam penelitian ini dikaji metode penentuan posisi ITCZ berdasarkan data Geostationery Meteorological Satellite serta pola gerak ITCZ tiap bulan. Penentuan posisi gerak ITCZ dilakukan dengan menggunakan persamaan regresi linear sederhana dan persamaan polinom orde dua/tiga. Dengan persamaan regresi linear sederhana dan polinom orde dua/tiga posisi ITCZ dapat ditentukan dengan ketepatan yang cukup baik. Posisi rata-rata ITCZ pada bulan Januari berada di belahan bumi selatan, sedangkan bulan April, Juli dan Oktober berada di belahan bumi utara. Dengan persamaan polinom orde dua/tiga pada bulan April, Juli dan Oktober posisi rata-rata ITCZ berada 2º lintang lebih ke utara dan pada bulan Januari berada 3º lintang lebih ke selatan dibandingkan dengan persamaan regresi linear sederhana. Untuk bulan Januari, April dan Juli penentuan posisi rata-rata ITCZ dengan persamaan polinom orde dua/tiga relatif lebih tepat, sedangkan dengan persamaan regresi linear sederhana terjadi penyimpangan yang cukup besar. Sebaliknya untuk bulan Oktober dengan persamaan regresi linear sederhana relatif lebih tepat. Secara umum pola gerak ITCZ tiap bulan (1994-1997) mengikuti gerak matahari. Pada bulan Desember-Februari ITCZ bergerak ke selatan ekuator, bulan Maret-Mei bergerak ke utara menuju ekuator, bulan Juni-Agustus bergerak lebih jauh ke utara dan bulan September-November kembali bergerak ke selatan. Posisi rata-rata ITCZ paling selatan pada 3° LS (bulan Maret), sedangkan posisi rata-rata ITCZ paling utara pada 14° LU (bulan Agustus). Penyimpangan posisi ITCZ dapat terjadi karena pengelompokan jenis awan yang kurang spesifik, juga dapat disebabkan oleh penyimpangan sirkulasi Walker dari keadaan normal. Luas zone ITCZ pada bulan Januari, April, Juli dan Oktober berubah-ubah baik dalam tahun yang sama maupun antar tahun (1994-1997).
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