Judul: Effetcs of Pretreatment and Drying Temperature on Quality of Dried Bamboo Shoots (Dendrocalamus membranaceus Munro)
Abstrak: Whole bamboo shoots (Dendrocalamus membranaceus Munro) freshly harvested in Doi Tung were blanched at 90-100 ⁰C in various concentrations of sodium metabisulfite solution (0, 0.5%, 1.0%, and 1.5%) for ten minutes, as pretreatment, and then dried at various temperatures (50 ⁰C, 60 ⁰C, and 70 ⁰C) using a laboratory scale hot air drier. Effects of both pretreatment and drying temperature on quality of dried bamboo shoots were evaluated. There were seven parameters observed: drying time, aw, color, rehydration ratio, shrinkage, firmness, and total residual sulfites. Results showed that drying time decreased with increase in the drying temperature (p<0.01) while both pretreatment and drying temperature had no significant effect (p>0.05) on aw and shrinkage of dried bamboo shoots. Moreover, L* value, b* value, and rehydration ratio increased with increase in concentration of sodium metabisulfite and decrease in drying temperature, whereas a* value increased. The higher b* value and rehydration ratio (p<0.01) were found in samples blanched in 1.5% Na2S2O5 solution and dried at 50 ⁰C and samples blanched in 1.0% Na2S2O5 solution and dried at 60 ⁰C. It was also observed that total residual sulfites in dried-sulfited sample was quite high, ranged from 1250 to 3378 ppm SO2 while the sample blanched in 1.5% Na2S2O5 solution had higher residual sulfites than the other concentrations. Based on the parameters, sample blanched in 1.0% Na2S2O5 solution and then dried at 60 ⁰C was chosen to be the best sample. Results of rating hedonic test confirmed that the rehydrated of the best sample was more preferrable than the rehydrated-commercial dried bamboo shoots. It is suggested that blanching in 1.0% Na2S2O5 solution and then drying at 60 ⁰C is a better drying condition to produce dried bamboo shoots with a desired quality and applicable in Doi Tung.
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Judul: Penanganan Awal dan Pengeringan Umbi Talas (Colocasia esculenta (L.) Schoot) menggunakan Sunbeam Food Dehydrator Tipe DT5600
Abstrak: Drying process had become an effort to process taro corms as the raw material for industry. The main problems of taro corms post-harvesting before drying process were the pre-treatment and how to process the slice of taro corms. The objectives of this research are to study the dehydrator temperature effect and pre-treatment before drying process of taro corms using Sunbeam Food Dehydrator DT5600 (55 ᴼC and 75 ᴼC) to the dried taro corms quality, also to assess the performance of Sunbeam Food Dehydrator DT5600. The slice taro corms had 2 mm thickness. There were four treatments before drying, the first was no treatment as control, the second was blanching treatments of the slice of taro corms within the 7 liters water at temperature of 80 ᴼC for 15 minutes, the third was blanching which followed by the soaking within the 10% concentration of sodium chloride solution, and the fourth was same as third treatment which followed by blanching using 2 g/kg of sodium metabisulphite at temperature of 80 ᴼC for a minute. The result showed that taro which is dried at drying temperature of 75 ᴼC more efficient than that of dried at drying temperature of 55 ᴼC. The drying rate and efficiency of taro drying were 43.84 %bk/jam and 17.38% respectively. Dried taro is categorized into super quality for first and second treatments, first quality for fourth treatments and second quality for third treatments. The pre-treatment of taro drying by using blanching and by the soaking within 10% concentration of sodium chloride solution is recommended to reduce oxalate of dried taro until 81.11%.
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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