Judul: Seleksi Bakteri Asam Laktat Indigenous Indonesia untuk Starter Keju
Abstrak: Indonesia was a tropical country which high of an organism biodiversity, include to their microorganism such like the Lactic Acid Bacteria that familiar to food spontaneous fermentation. However, the exploration to Indonesia’s LAB was rarely. In the other hand, cheese and their derivatives was a famous food product in Indonesia. The LAB can being indigenous commercial starter for the exploration. Therefore, the objects of this research were (1) to screen LIPI Cibinong’s LAB isolates which have high potential to make coagulum; and (2) to get the selected cheese starter from the high potential isolates. The research methods which will used to get the high potential isolates were screening acid potential, screening protease potential, and screening coagulant potential; and to get the selected cheese starter were making a high potential isolates growth curve and assaying to cheese laboratory made with parameters: measurement of pH, rennet activity assays,yield calculations and sensory test. The result of this research were (1) from the 39 LIPI Cibinong’s isolates, DR 1-7-1 was the high acid potential isolate with Lactic Acid Index 3.25, DSB 4-2 was the high protease potential isolate with Protease Index 3.82, DR 2-2-3 and DSB 4-2 were the high coagulant potential with form coagulum time on 24 hours; and (2)the optimum growth of DR 2-2-3 and DSB 4-2 were 24 hours and the selected cheese starter was DR 2-2-3 isolate 6% with rennet 0.01% because thatconcentration combination of starter and rennet, can make the forming time of coagulum to be faster than control. That was 6 minutes (control) to be 3 minutes (DR 2-2-3 6% with rennet 0.01%)
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Judul: Karakteristik keju lunak hasil fermentasi dengan bakteri asam laktat indigenus
Abstrak: Milk with a high fat and protein content can be used in cheese production. Initially, cheese products in Indonesia are imported for supply the specific consumer. However, the cheese has become a kind of common food for Indonesian people. Cheese is usually consumed as a supplement and a flavor enhancer of food. This growing triggers some dairy-based food industry in Indonesia to produce cheese and its diversification. The diversifications are ranging from fresh to processed cheese. One of innovation product is the probiotic cheese products. This study used three different types of lactic acid bacteria: 1) Lactobacillus acidophilus RRM-01 (LA-RRM01), 2) Bifidobacterium longum RRM-01 (BL-RRM01) and 3) Lactococcus lactis DSB 42 (LL-DSB42) to produce a functional cheese product by fermentation of lactic acid bacteria. Analysis was performed on the quality of fresh milk using a pH meter and milko tester, bacterial culture are prepared by refreshment and propagation, soft cheese production by the addition lactic acid bacteria cultures. The analysis of the products includes physical (yield), chemical (pH, moisture content, protein rude, crude fat and ash) and microbiological (lactic acid bacteria). The research used the factorial completely randomized design in three replication. The parameters are pH value, carbohydrate, LAB population. Analysis of crude protein, crude fat, moisture content were performed by randomized block design (RBD). The data were collected from seven treatments of lactic acid bacteria culture (LA-RRM-01/LA, BL-RRM-01/BL, LL-DSB 42/LL, BL-LA, BL-LL, LA-LL and BL-LA-LL). The data were analyzed by analysis of variance (ANOVA) and followed by Duncan test for multiplication comparison test. The Sensory analysis was tested by non-parametric analysis. Fresh milk quality of FH cows with a fat content (4.9%), protein (3.8%), lactose (4.0%) and pH (6.7) is accordance with the SNI 314.1:2011 standard. The cheese was produced contain the yield ranging from 17.9% -22.5%, pH values from 5.10 to 5.79, and classified as soft cheese. The treatment did not effect in moisture content, crude protein and ash, but there were significant differences (P <0.05) in the carbohydrate and crude fat either in single culture or culture of the three bacteria. The use of single culture bacteria or in a mixture did not inhibit the other cultures. The population of lactic acid bacteria in the products is approximately 9 log10 cfu g-1. The hardness product cultured by mixed two bacterial cultures were significantly different (P <0.05) with that of three bacterial cultures. Fifty panelists gave neutral and like slightly assessment for the color, flavor, aroma and general preferences of soft cheese (value 3.6 to 5.3), dislike slightly for the appearance of texture (value 2.5 to 3.6). Panelists assessment of the hedonic quality were white-yellow (value 5.0 to 6.1), bitter-sour taste typical cheese-(value 4.4 to 5.0), the typical cheese-sour aroma (value 5.3 -5.6), texture (value 5.2 to 6.4) and consistency (value 5.3 to 7.1). Because of high water content in all the soft cheese products (> 55%) and looks watery consistency, the texture of the products is less preferred by the panelists. Panelists felt bitter and sour after taste. It was concluded that the milk used for cheese production meets
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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