Protein dan Peptida Susu Kambing serta Potensinya sebagai Antibakteri
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Date
2015Author
Lestari, Diana
Suhartono, Maggy T.
Kusumaningrum, Harsi Dewantari
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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.
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- MT - Agriculture Technology [2209]