Judul: Study on the potency of acetate, sodium benzoate, and potassium sorbate as preservatives for tofu
Abstrak: Tofu is one of Indonesian traditional food which is made from soybeans (Glycine max). Tofu stored in the refrigerator has shelf life for about 2 days and only a half day when it stored at ambient temperature. This is the reason why illegal practice of the using formalin has occured in Indonesia. The objective of this research was to evaluate the capability of sodium benzoate, potassium sorbate, and acetic acid as preservatives for tofu. The expected result is giving an alternative of method in preserving tofu with legal food additive. The concentration of sodium benzoate and potassium sorbate that was used in this research is 40% of ADI. Tofu was divided into five main treatments, tofu that soaked in water, acetic acid, acetic acid-sodium benzoate, acetic acid-potassium sorbate, and acetic acid-sodium benzoate-potassium sorbate. Several tests such as, texture analysis, total plate count (TPC), pH measurement, color measurement, and organoleptic test, were conducted to measure the effectivity of each preservative to prolong the shelf life of tofu. TPC assay showed that all of the combinations of preservatives were effective to reduce the number of microbes. The texture of tofu became soften after soaked in acetic acid and analyzed using Texture Analyzer. The result of texture analysis showed that the combination of acetic acid-sodium benzoate had the softest texture (0.46 N) compared to the other treatments. pH measurement showed that acetic acid had the lowest value (4.16) compared to the other treatments. The result of the research showed that acetic acid 1.5% (v/v) did not have the capacity as preservative for tofu. The use of acetic acid 1.5% (v/v) caused sour taste that made tofu could not be accepted by consumers. However, all of the combination of preservatives showed good effect in preserving tofu when stored at room temperature. Soaking sour tofu in 3% (w/v) salt solution for 3 minutes could increase the acceptance of consumers.
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Judul: Proses Pengolahan Tahu Sutera Instan (Silken Tofu)
Abstrak: Silken Tofu is product one of processed soybean. Althought named tofu, but different with tofu usual, because silken tofu have texture that gantle and soft. Siken tofu is product of gel protein soybean that has nice taste, soft texture, relatively inexpensive of price, easy to disgeted and has contents hight protein. Common problems which containt the tofu is shelf life of tofu short time. This problems because of hight wate content that specifically for shape into crude until usually has found case of used formalin to shelf life of tofu that done by producers. Production tofu in dry method with using powder silken tofu instant expected solution from this problems. Making tofu dry method using soy protein that has been dried by spray drying, so adjust to make tofu with they needs. Siken fofu instant based yield of analysis, water content, protein content and colour rendition obtained soybeans and water ratio with is anable to produce the best soy flour protein is 1 : 5. Results of the analysis water content and protein content with the best coagulant use apple vinergar 12% and calcium chloride (CaCl2) 2%. Value water content and protein content of silken tofu instant coagulant with aple vinegar 12% of has value 76.63%, and 45.58%, while coagulant with calcium chloride has value 74.89%, dan 38.23%.
Keyword: processing silken tofu instant., silken tofu

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