Judul: Kajian proses pembekuan dan daya simpan kultur bakteri laktat asal dadih untuk produksi kultur starter
Abstrak: Dadih is a traditional fermented milk of West Sumatra - Indonesia, fermented in bamboo tube. Some srains of lactic acid bacteria isolated from Dadih possess probiotic properties; hence, it is important to study the effect of preservation of the lactic acid culture on their viability and biochemical properties during frozen storage. Four strains of lactic acid bacteria isolated from Dadih which have good antimutagenic properties are Lactococcus lactis subsp lactis R-22, Leuconostoc paramesenteroides R-51, Lactobacillus casei subsp casei R-52 and Leuconostoc paramesenteroides R-62. The lactic culture were preserved by freezing at -20°C by different freezing methods, frozen in deep freezer (slow freezing) and frozen in dry ice-ethanol mixture (fast freezing). Glycerol 10%, dimethylsulfoxide (DMSO) 10% and skim milk 10% were used as cryoprotectant with phosphat buffer pH 7,0 as control. The cultures were stored in deep freezer at -20°C as well as -70°C. The addition of glicerol 10% in Lactobacillus casei subsp, etc
Keyword: Dadih cultur, Lactobacillus casei, Deep freezer

Judul: Pembuatan Starter Kering Bakteri Asam Laktat dan Pengaruhnya terhadap Karakteristik Dadih Susu Sapi yang Dihasilkan.
Abstrak: Dadih is a traditional food from West Sumatera resulted from natural fermentation of buffalo milk. This natural fermentation process involves a number of microorganisms, including gram-positive and gram-negative bacteria. The presence of gram negative bacteria that are pathogenic can become an obstacle to get safe and healthy food product to consume and easy in the marketing of products, due to the security aspect is less reliable. The processing through a more controlled fermentation process using lactic acid bacteria starter without involving the bacterial pathogens are expected to improve the quality of the resulting dadih. The provision of culture with the preservation in the dry form will facilitate the handling of starter cultures, so that the fermentation is more controlled and the product quality is more assured. Besides that, the availability of dry starter cultures will facilitate the distribution and transportation of starter cultures because dry starter cultures can be sent for long distances without losing the activity of Lactic acid bacteria and have a long storage. Raw materials used in the manufacture of dadih in West Sumatera derived from buffalo milk. The availability of buffalo milk is very limited, that, the alternative used is cow modified with skim milk and jelly therefore it is expected produce Dadih which has the characteristic similar with dadih from buffalo’s milk. This study aimed to verify the making of dry starter of lactic acid bacteria (the combination Streptococcus thermophilus and Lactobacillus casei also Lactobacillus bulgaricus and Lactobacillus casei) and its effect towards the characteristic of resulting cow’s milk dadih. Various analytical results indicate that the interaction of combinations of lactic acid bacteria starter and concentration of dried starter powder of lactic acid bacteria significantly affect to the pH value and moisture content of dadih. interaction of a combination of lactic acid bacteria starter and dried starter powder concentration of lactic acid bacteria did not influence significantly to the value of titrable acid total, viscosity, ash content, and the total amount of lactic acid bacteria in dadih. Friedman test results showed that the assessment of panelists for color, aroma, taste, texture, and general acceptance of dadih was not significantly different. Based on weighting method for the determination of the best dadih products, showed that dadih fermented by a combination of starter S. thermophilus: L. casei (1 : 2) as much as three grams of powder has the highest weight value. Thus, the recommendation of the best dadih product is dadih product fermented by a combination of starter S. thermophilus : L. casei (1: 2) as much as three grams of dried starter powder. Microbiological test results showed that the lowest total lactic acid bacteria contained in dadih products, that is 8.4 x 109 CFU/ml. Thus, the dadih is eligible as fermented milk for the minimum amount of total lactic acid bacteria ranged 106-109 CFU/ml (Sari, 2007).
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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