Judul: Aplikasi kitosan dengan penambahan esensial oil kunyit sebagai pengawet dan edible coating produk tahu
Abstrak: Tofu is a nutritious and digestible food that has been widely consumed in Indonesia. However it is a perishable food that has a short shelf life due to its rich nutrients and high moisture content. This characteristic makes both producers and consumers would like to prolong it. The objective of this research is to apply chitosan enriched with Curcuma Essential Oil (CEO) as curdling agent and as antimicrobial coating to prolong the shelf-life of tofu. Physicochemical film and antimicrobial properties of chitosan are studied. Antimicrobial activity was tested against food pathogenic and spoilage bacteria, namely Escherichia coli and Bacillus cereus, respectively. All characteristics of tofu except texture in the sensory evaluation, were not significantly differences between the chitosan-tofu, chitosan-EO tofu and control tofu. The obtained results revealed that the application of chitosan enriched with CEO as coating and curdling agent had a little effect on the quality attributes. The shelf life of chitosan coated tofu is longer by 3 days than control tofu without chitosan
Keyword: 

Judul: Aplikasi Kitosan dengan Penambahan Ekstrak Bawang Putih sebagai Pengawet dan Edible Coating Bakso Sapi
Abstrak: Chitosan is biopolymer derived by deacetylation of chitin, a major component of the shell of crustacean such crab, shrimp and crawfish. Chitosan is suitable as natural preservative and antimicrobial of edible coating. The applications of chitosan in food industries for food formulation for binding, gelling and thickening and stabilizing agent. Chitosan has the antimicrobial activity that can inhibit the growth of bacteria and fungi. The objectives of the research were to enchance the antimicrobial capacity of chitosan by adding garlic extract and to apply it for extending the shelf life of beef meatball. Antimicrobial activities of chitosan and chitosan enriched with garlic extract were assessed by agar diffusion methods. It showed that chitosan solutions of 1% (w/v) enriched with garlic extract 2% (v/v) could inhabited Pseudomonas aureginosa and Bacillus cereus. The application chitosan enriched with garlic extract as preservative shelf life agent could extend the shelf life of meatball only for 12 hours while its application of chitosan as edible coating could extended the shelf life of meatball until 24 hours for the same condition (stored at room temperature). This result revealed that the application of chitosan with or without garlic extract as edible coating were more effective in controlling microbiological growth in meatball than as preservative agent. The physical analysis of the final product showed that the application of chitosan as preservative agent could increase the gel strength of meatball due to its gelling properties. The microstructure of meatball surface ware observed with SEM. The micrographs showed that the surface of meatball coated with chitosan were more smooth and compact that those of meatball without coatings.
Keyword: 

Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular