Judul: Potensi Antimikroba Kayu Siwak (Salvadora persica Wall.) terhadap Staphylococcus aureus dan Pseudomonas aeruginosa serta Aplikasi pada Bakso Daging
Abstrak: Preservation of processed meat products have been carried out with the aim of extending the shelf life. Preserving is one important factor considering the risks that may be posed and one of them is the use of hazardous chemicals as preservatives. One of food product which is vulnerable given the addition of formalin was the meatball. Siwak has been known to have antimicrobial activity but its application for foods has not been widely explored. The study consist of four phases, extraction of siwak well diffusion test, dillution broth to determine MIC, and applications in meatballs. Well diffusion test showed that siwak’s extract has antimicrobial activities against Staphylococcus aureus bacteria and Pseudomonas aeruginosa bacteria which have inhibition zones of 21.10 mm and 20.11 mm respectively. Dillution broth test showed that the minimum concentration which is can inhibit bacterial growth was 50% (v/v) of siwak’s aqueous extract. Application in meatballs showed that siwak extract can hold down bacterial growth up to 98,17% in Staphylococcus aureus bactery.
Keyword: natural preservative., antimicrobial activity, siwak, preservation

Judul: Pemanfaatan Redistilat Asap Cair Cangkang Kelapa Sawit sebagai Bahan Pengawet Alami pada Bakso Sapi
Abstrak: The misapplication of chemicals, such as formaldehyde, for preservative is still found in processed food ingredients. The use of these materials can be replaced by redistilled liquid smoke from oil palm shells. Identification using gas chromatography-mass spectrometer showed that there were no harmful compounds such as tar and polycyclic aromatic hydrocarbons. Acid level and pH of redistilled liquid smoke on 80 °C possess better result with the respectively values were 5.14% and 2.26. The LC50 value with brine shrimp lethality test method is 0.16%. Inhibition zone on the antibacterial test to Staphylococcus aureus with redistilled liquid smoke on 0.1% and 0.8% were respectively 6.11 mm and 6.08 mm while to Escherichia coli were respectively 0 mm and 6.95 mm. The inhibition zone redistilled liquid smoke was lower than 100 ppm chloramphenicol, which were 14.17 mm on S. aureus and 12.60 mm on E. coli. Redistilled liquid smoke with concentration of 0.8% was better than the concentration of 0.1% in inhibiting the growth of total microbial on the meatballs. The addition of redistilled liquid smoke was able to inhibit the growth of microbial up to 18 hours at room temperature.
Keyword: Bogor Agricultural University (IPB), redistilled liquid smoke, oil-palm shells, natural preservative, meatball

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