Judul: Rheology and Physicochemical Properties of Spray Dried Glucomannan Extracted From Elephant Foot Yam (Amorphophallus oncophyllus) Tuber
Abstrak: Indonesia has many kinds of cereals and tubers which are rich in carbohydrates. One of the potential tubers in Indonesia is elephant foot yam, also known as iles-iles. Elephant foot yam has two important compounds, glucomannan and calcium oxalate. Mannan flour is made from elephant foot yam tuber and has more glucomannan content than the other component in that flour. Glucomannan has many special characteristics, such as capable to form thick solution in water, capable to form gel and capable to form thin and water impermeable film by adding sodium hydroxide or glycerin. First stage in this research was glucomannan extraction in water, then the glucomannan extract (also called slurry) was dried using spray dryer. During drying process, the solid compounds including glucomannan became flour. Then, some analysis were performed to evaluate the physicochemical and rheological characteristics of the mannan flour. Based on result of the research, grating was the chosen treatment used for tuber size reduction. Meanwhile, gradual water changing for 4 times (ratio of tuber: water was 1:5 for one time water changing, thus the total ratio of tuber : water was 1:20) was the chosen treatment for glucomannan extraction. Browning prevention was performed by soaked the size reduced tuber in 1000 ppm sodium metabisulfite solution for 10 minutes. The highest yield and lightness value on mannan flour obtained from laboratory scale production is from slurry which came from the grating treatment and gradual water changing. The yield and lightness value are 3.10% and 98.74, respectively. Output of mannan flour obtained from pilot plant scale production is 3.15%. Based on result of proximate analysis, mannan flour obtained from pilot plant scale production has 9.96% of water content, 6.70% of ash content, 5.64% of protein content, 1.16% of fat content, and 86.49% of carbohydrate content (by difference). The lightness value of mannan flour obtained from pilot plant scale production is 90.37, while the whiteness value is 87.64. The lightness and whiteness value of mannan flour, both from laboratory scale and pilot plant scale production, are higher than the lightness and whiteness value of commercial mannan flour. Glucomannan content and glucomannan yield of mannan flour are 42.99% and 21.39%, respectively. The elephant foot yam tuber which is used as raw material has 6.29% glucomannan content. Mannan flour obtained from spray drying process has good solubility when rehydrated in water. According to rheology characteristics, viscosity of 10% (b/v) mannan flour solution showed no dependency to shear rate and time while viscosity of 11% (b/v) mannan flour solution showed pseudoplastic and thixotropic behavior. Viscosity of 10% (b/v) and 11% (b/v) mannan flour solution decreased due to the heating process until it reached temperature 90OC. Due to the low measured viscosity, mannan flour obtained from spray drying process cannot be used as thickener and gelling agent. Same rheology measurements were also done to 7 mannan flour obtained from different sources, such as drum drying method, conventional (oven drying) method, and commercial mannan flour.
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Judul: Pemurnian Glukomanan secara Enzimatis dari Tepung Iles-iles
Abstrak: Glucomannan is typical polysaccharide derived from konjac tuber. Conventional fractionation of glucomannan in konjac flour is by mechanical separation method, but it produces low purity glucomannan flour and needs further purification methods. This research is explored the glucomannan purification by enzymatic hydrolysis directly from konjac flour. Since konjac flour mainly consisted of starch, glucomannan and fiber, in this research sole thermophilic α-amylase enzyme and consortium of enzymes (amylase, xylanase and cellulose) were applied on 50 and 65 oC of incubation temperature for 2 hours. The results showed that consortium of enzymes can not be used for glucomannan purification; because glucomannan component is hydrolyzed by xylanase and cellulose. Glucomannan flour produced from sole α-amylase with incubation temperature of 50ᵒC has the highest yield (42.7%) compared to incubation temperature of 65ᵒC (31.6%). Duration of incubation also influenced to the glucomannan yield, and two hours of incubation time gave the best glucomannan flour with highest yield (37.0%), purity (46.1%), viscosity (42.3 cPs) and good whiteness (12.7%). Enzymatic hydrolysis of konjac flour also produced starch syrup (DE 55.6 – 77.9) as by- products.
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Judul: Identifikasi jenis-jenis ordo coleoptera koleksi laboratorium hama hutan fakultas kehutanan
Abstrak: Salah satu ordo yang termasuk ke dalam kelas insekta adalah Coleptera. Coleoptera berasal dari kata coleo yang berarti selubung dan petra yang berarti sayap. Nama daerah ordo coleoptera di Indonesia adalah kumbang. Ordo Coleoptera sebagai komponen penyusun ekosistem mempunyai peranan yang penting dalam kehidupan manusia baik merugikan maupun menguntungkan, tergantung pada cara mengelola potensi ordo Coleptera.
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