Judul: Effectiveness of Microwave Oven against B. cereus to Reach Food Safety Objective in Cook-chill Foods
Abstrak: Cook-chill foods are meal that being cooked and then chilled quickly until further consumption. Usually before being consumed, the foods are reheated by the consumers to improve the organoleptic property and also to destroy bacteria. One of the things that need to be considered is that cook-chill foods that are originated from grains like rice or wheat are vulnerable to be contaminated by pathogen, especially Bacillus cereus. Another problem is that on the packaging of specific cook-chill food that being investigated, there is only instruction manual on how to reheat the food with 1800 W microwave oven. Microwave oven that is being used in household level is usually lower than 1000 W, so there is a possibility under-cooking may happen because there is no standardization on how to heat food with microwave on household level. The research was conducted in five steps, which were; (1) investigation of standard plate count and B. cereus count on two cook-chill foods (spaghetti bolognaise and black pepper chicken rice), (2) challenge test on those cook-chill foods to evaluate the growth of B. cereus on cook-chill food on 15oC, (3) challenge test to evaluate inactivation of vegetative cells and spores of B. cereus by microwave oven (850 watt and 410 watt), (4) to evaluate if FSO of those cook-chill foods could be achieved based on data gathered in the previous results, and (5) to study the effect of microwave oven and moist heat against leakages of nucleic acids and proteins of B. cereus. The results of this research were that microwave oven with 850 watt power could still reach food safety objective (FSO) when cook-chill foods were being reheated for the recommended time on the packagings (45 seconds for spaghetti bolognaise and 2 minutes for black pepper chicken rice), however when using 410 watt microwave oven, FSO could not be achieved. The mechanism of which why microwave oven could destroy vegetative cell and spores of B. cereus was also investigated. The result was that heat treatment using microwave oven differed when compared to moist heat since heat treatment using microwave oven caused leakages of nucleic acid and protein content of the vegetative cells and spores of B. cereusin much larger effect than moist heat.
Keyword: cook-chill foods, Bacillus cereus, microwave, rice, spaghetti, food safety objective

Judul: Ketahanan Spora dan Sel Vegetatif Bacillus Cereus Terhadap Suhu Awal Preparasi dan Selama Penyimpanan Makanan Pendamping Asi Bubuk Instan
Abstrak: Bacillus cereus is one of foodborne pathogenic bacteria and constituting one of ‘emerging’ pathogen that can cause serious disease in baby, such as low body weight and neonatal premature. Data in Indonesia on B. cereus contamination incidence in food are limited. This research aimed to evaluate the survival of B. cereus spores and vegetative cell in infant food (MP-ASI), during preparation at various water temperature (30,70, and 90 oC), to analyze the ability germination of B. cereus spores at room temperature and to evaluate the survival of B. cereus spores during storage of infant food instan powder. In addition, the microbiological quality of infant food instan powder i.e. total plate counts and the presence of B. cereus were also determined. The result showed that the average total B. cereus in sample were 1.85 log CFU /g with a range of 1.73 log CFU /g to 2.06 log CFU /g, the TPC was in range of 0.86 log CFU /g to 2.53 log CFU /g. The water temperature for preparation affected significantly in reduction of vegetative cell B. cereus. B. cereus spores can germinate in infant food (MP-ASI) and the growth of population bacteria were increase ≥ 1 log during 3 hours, at room temperature (28-29 oC), after preparation using water at 30 ⁰C. Water temperature of 70 °C found as the optimum temperature for preparation. The spore of B. cereus can survive on dry condition.
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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. ,,,
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular.